Testing hotspots in your oven – using kitchen science

Every avid baker or cook knows their oven almost instinctively, learning its eccentricities over time. These foibles include uneven temperatures and, despite modern fan technologies, when an oven has aged a little it is likely to develop hot and cold zones rather than uniform temperature.

It is dificult to know exactly what these hot or cool spots are doing or where they are in your oven unless you test. I have a fun, kitchen science way of testing for hotspots. You might even want to get your children to help you (though of course be careful as it does involve a hot oven and hot sugar).

Once you know which areas in your oven might be cooler and which might be hotter, you can use this to your advantage. Or, you might find out that your oven is perfect throughout (although the chances are slim!).

Good cooks know that ovens fluctuate and informed recipes might tell you to put the tray on the top, middle or bottom shelf making use of the fact that heat rises, for example. This isn’t something that’s just confimed to non-fan ovens, although it is more profound without a fan.  As someone who uses their oven a lot, you’ll be instinctively turning bakes round mid-way through cooking time or knowing to place roasting potatoes on the top rack so they crisp up nicely as you’ve got to know how yours work a little – but testing it will give you more knowledge.

Temperature variations can seriously affect your food. This is especially important in baking, where chemical reactions caused by certain temperatures are required. It’s less important for ‘normal’ cooking as you can just leave your roast or casserole in a bit longer. For example, incorrect temperatures or hot or cold spots can seriously affect the rise of a cake.

Which? has a fantastic online advice guide on ‘Why oven temperature matters‘ which delves in to the effect of even slight variations of temperature on the finished quality of cakes. Hot and cold spots in your oven can affect your bake as dramatically as setting the temperature incorrectly or will cause lopsided or irregular finished products.

There are a number of free online resources and advice guides on the Which?  website that cooks and bakers might be interested in as well as this one, such what all the attachments do on your stand mixer. (Do search by appliance type, then look for the advice guides on that page).

effect-of-oven-temperature-on-baking-455659

Image (used with permission) from the Which? advice guide ‘Why oven temperature matters’

What about oven thermometers?

Oven thermometers may seem like a good idea – but they are only measuring the point in the oven where you have placed them. This could be a hot spot, it could be a cold spot or perfect – do you know which? A guage is not indicative of what’s going on everywhere in your oven, unless it your oven is definitely a constant temperature throughout (and if it is I wonder whether you might need a gauge?).

The most likely area for a cold spot to appear is close to the door, because some heat may leak from the seal (especially in older ovens) and it’s furthest from the heating element. And this is where guages are placed so they can be read through the glass…

Understanding the test

This whole test is based around the fact that the melting point of sucrose is 186°C  / 367°F (actually sugar does not ‘melt’ but rather decomposes – but that’s for another time!).

Also, some sugars have a subtly different chemical formulation which will affect this melting point a little, but as this is not a lab-worthy experiment so this will matter little to us. Do try to use normal white table sugar, but it doesn’t really matter too much.

As the melting point is 186°C and oven temperatures go in 5°C intervals, this is how we will approach the test.

A note about Farhenheit. Fahrenheit is less easy to get close to the melt point of sugar because it jumps on your dial in larger increments – usally in 25°F jumps. 180°C can be mapped to 350°F and 190°C as 375°F. This means it will be very difficult for a user of a Fahrenheit oven to get the equivalent of 185°C close to sugar melting point, which should be 162.5°F. If your oven goes incrementally you may not be able to do this at all. If your dial moves smoothly try to get it halfway between 250°F and 375°F 0 I cannot guarantee this will work at all as I do not have access to a Fahrenheit model to test this).

First, we heat the oven to 180°C  – if anything melts at this stage your oven is very hot. We should expect to find the sugar intact (although you may find some of the sugars are starting to turn)

Then we heat to 185°C – you may find some (or all) of the sugars melting or melted. This indicates a slightly hot area but it’s only just shy of the proper temperature, so this is fine

Next, heat to 190°C – all the sugar should be melted by now. Any sugar that isn’t a little pool of caramel indicates a cool spot in your oven. I’d expect to see it either completely melted or starting to change (cool spot). Any sugars that are still crystalline indicate a very cold spot indeed

What you will need:

  • Your oven to be cold when you start (don’t pre-heat)
  • Empty your oven of all baking trays etc, just leave its wire racks in place
  • Kitchen foil
  • Granulated white sugar
  • Pen and paper to capture your results (use the PDF print out below if you like)

How to do the test

  1. Cut up ten 10cm squares from the foil and make a little cup with each of them. The easiest way to do this is press each square into a small dish.foil_Fotor
  2. Draw yourself a little oven map such or use this PDF print out I’ve created:

DOWNLOAD and PRINT OUT Oven Temperature Map Slide1

  1. I found it easiest to jot down the temperature when the sugar melted, then mark those that melted early (ie at 180°C) with red and those that melted late (ie 190°C) with blue.
  2. Place five foil dishes on each wire rack in your oven – one in each corner and one in the middle on both racks. This will give you a good reading (ie corners and the middle of both top and bottom shelves)
  3. Close the oven door and turn the oven on to 180°C – be sure to use your fan option.
  4. When the oven temperature is achieved, give it a minute then open and check the little foil pots. Have any melted or begun to melt? Jot down on your oven map which ones have changed. If sugar has melted (or begun to melt) at any points in the oven, these are hotspots.
  5. Close the door again and turn the temperature up to 185°C
foilmelted

Foil pots – the one at the top has melted sugar, the one in the foregraound is just starting to change (note it’s not white anymore and the crystals are less apparent)

  1. Give it a minute after it reaches temperature and check the post again. Note down which ones are melted or melting. This is close to being perfect temperature
  2. Close the door again and turn it up to 190°C
  3. All the sugar should be melted by this stage, ideally. Any that are still crystalline are very cold spots, and that are on their way to melting aren’t quite as bad but you still need to be aware of them.

What now?

Now that you are armed with this basic map of your oven and hot and cold spots, you can use it to your advantage. Place cakes in the most stable regions: an area with no cold or hot spots. Place food that needs the Maillard browning reaction in a hotter area. Open the door and ‘waft’ the oven with a tea towel half way through cooking (never to be done with cakes or anything that will sag!) to distribute the heat and help the work of the fan. Is it cold near your door? Check your seals are working and whether you can replace them.

I hope this helps you. I’d be so interested to hear if you try this and discover somethign about your oven. For me, I always assumed my oven was running very hot but it’s fine throughout, except at the very front on both racks where the fan clearly isn’t strong enough to push the heat round (or I have a bad door seal that needs looking at) as it’s cold towards the door.

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Chemical leaveners / raising agents

bakingpowder

There are several ways in which to get breads, cakes and other baked goods to rise. Some of these methods have been used for hundreds of years, such as yeast or whipped eggs, and some are a very modern introduction (chemical raising agents).

Types of chemical leaveners/raising agents

Leaveners can be classed as natural, chemical or mechanical. Natural includes eggs and yeast, chemical is bicarbonate of soda, cream of tartar etc and mechanical includes the incorporation of air by physical methods (eg whipping cream or eggs) or rise created by steam or dry heat [steam/heat could also be classed as natural].

What exactly am I rambling on about

I’m only covering chemical leaveners/raising agents in this piece. I’ve actually been researching and reading up on this on and off (not continually!) for over a year now. I never imaged there was so much to it.

I set out to discover why and how chemical raising agents work in my baking. I’ve read through chemical formulas, explanations of the chemical process involved and undergraduate-level books detailing experiments all to get to here. Some of it I didn’t grasp at all, some made sense at the time but now I’m a bit fuzzy on it and plenty did made sense. I’m no scientist, so I think there’s little point in me simply regurgitating the really complex areas I’ve researched or even drawing out the chemical formulas and reactions that are involved. I might get such specific details wrong. I may not have understood it all fully. There’s a chance I could misinterpret it. So, all I’m aiming to do here is pass on what I’ve come to understand through this research about what is going on inside my cake (or other bake)  to make it rise, and if there is anything I can do to get the best results in my kitchen using raising agents.

Which raising agents

In the UK we tend to only use bicarbonate of soda as a chemical raising agent (though others are available – see later).

In a commercial baking setting (in the UK to some extent but more commonly elsewhere) sometimes baking ammonia is used instead as it produces a drier food product but it does produce a little ammonia as a by-product of the chemical reaction. You may have come across its common/historical name of ‘hartshorn’. Baking ammonia’s use in cooking predates that of bicarbonate of soda.

You’re going to say, “What about Baking Powder?”

Well, baking powder isn’t one thing. It’s a pre-mixed product of bicarbonate and a powdered acid (in its most basic, truest sense). All the information I’ve written below on the basics of how bicarbonate works also relates to baking powder, apart from two important caveats:

  • you don’t have to manually add an acid (such as lemon juice) separately as it’s already included. This also means the ratio of acid to bicarbonate is already measured precisely for you
  • the addition of a third ingredient in some commercial baking powders is there to add a second reaction which occurs in the presence of heat. It has the effect in that the leavening process occurs ‘twice’ as it were – chemical reaction one will start to produce gases in your bake in a cold environment (ie as soon as you start mixing) and the second chemical reaction will be produced in the presence of heat (as it bakes).[In the USA most baking soda’s are “double acting baking sodas” and follow this recipe. The name “double acting” implies the two chemical processes. It’s difficult to give you a definition of what to expect with American double acting baking soda as there does not seem to be an industry standard and several chemicals appear interchangeable, dependant on the manufacturer’s “recipe” and whether the product is deemed kosher or not. You may find various combinations of acid and bicarbonate in commercial double acting baking soda, the ingredients of which can be pulled from a long list: sodium bicarbonate, sodium aluminium sulphate, acid sodium pyrophosphate, calcium acid sulphate, ammonium bicarbonate, tartaric acid to name just a few. Don’t worry about conversions of American recipes – just substitute any UK/European baking powder. The American double action isn’t twice as strong as baking powder, just it definitely uses this dual process. Its strength/potency is equivalent whether the baking powder you swap it for is single or double acting itself.]

Bicarbonate of soda is most commonly mixed with cream of tartar (this could be listed as potassium bitartrate or tartaric acid) to produce baking powder. This is a single acting baking powder. Some commercially produced baking powders will include a third chemical – as mentioned above – such as acid sodium pyrophosphate, to provide this additional, second action. Also, some commercially produced tubs of baking powder may have an added stabiliser or two to prolong shelf life and minimise reaction (and therefore spoiling) prior to use.

The basics of how bicarbonates work as a food leavener

Bicarbonate of soda/sodium bicarbonate is extremely alkaline and a chemical reaction occurs in the presence of an acid – for example, lemon juice or vinegar and some moisture. You can start the reaction with a dried acid (for example vitamin C powder or cream of tartar) but you will need to add some form of moisture.

Bicarbonate does not need heat for any chemical reaction with acid to take place.

As soon as you introduce the acid to bicarbonate (in the presence of a little moisture – there may even be enough in the air) the reaction will start. What this means for your bake is that the rise starts happening as soon as you start mixing. When using a chemical leavener get your bake in the oven as soon as you can – don’t leave your mix hanging about in the bowl before you use it as you’ll have ‘wasted’ some of the chemical reaction.

We know it as baking powder in the UK, but it’s also called baking soda (typically in the US and Canada), bread soda and cooking soda. Can be listed as sodium bicarbonate or sodium hydrogen carbonate and you can spot it on a list of ingredients as E500.

The trick to using bicarbonate of soda (and baking powder for that matter, but to a lesser extent) within baking and cooking is to perfectly balance the amount of bicarbonate to the amount of acid.

In the presence of an acid, bicarbonate starts to react and one of the products produced by this reaction is carbon dioxide; a gas. It’s this release of gas bubbles that causes the rise within your baking.

For example, if you used a vinegar (which is acetic acid) with your bicarbonate, the reaction would produce some water, carbon dioxide and a small amount of sodium acetate.

Note on bakers ammonia/ammonium carbonate: for ammonium carbonate the comparable reaction produces (a little less) water, carbon dioxide and ammonia. It does not need an acid to react but does need heat and moisture. As it produces ammonia as a by-product, its use at home should not be in large quantities. When included in a mass-produced product by a commercial food company the large amounts involved (and therefore larger amounts of released ammonia) can be controlled safely in a factory environment.

The reason it is still used rather than baking powder is all because of that drier baked result – so it’s typical to find baking ammonia in things like crackers and harder biscuits. If you’re looking out for it (to be nosey) on a product’s ingredients list it may well be included as E503 rather than named. Italian, German and Scandinavian recipes in particular are most likely to include baking ammonia. I have had success in directly substituting the same amount of bicarbonate of soda for ammonium bicarbonate within a recipe, reducing any liquid in the recipe by a small amount and replacing it with an acid (for example this could be as simple as using a teaspoon less of water and adding a teaspoon of lemon juice in its place) to recreate that drier texture and effect the chemical process.

However, as a caveat, if you are similarly trying to convert one of these recipes you may need some trial and error to get this balance right yourself. I have not yet attempted to bake with baking ammonia – I’m a little nervy of the ammonia if I’m honest! I may try to get some as it is available to buy online and, if so, I will update this post with how I got on.

It’s crucial that the amount of acid used balances out the amount of bicarbonate. Too little acid or a heavy hand with the bicarbonate and not all of the bicarbonate will be able to react. This will leave some bicarbonate behind, and you’ll notice that tell-tale alkaline-salty tang which can ruin a bake. Additionally, your bake may not be fully risen either if not enough carbon dioxide was produced.

If there is too much acid the reaction can happen at a facilitated rate and also you’ll be left with a very sharp tasting bake.

Even if there is too much acid the chemical reaction will still take place but it will start more vigorously and be over quicker. This sounds OK doesn’t it? Well, actually it’s not great news for the baker, as the reaction is quick and the gas is produced faster it will start to dissipate early and the rise it produced can go to waste.

For instance, when making a cake you need the bubbles from the gas to be captured as tiny cavities in the sponge mix as it cooks. Bubbles of gas will reach their maximum size within the sponge before dispersing as the cake heats up in the oven. In a perfect bake, as the cake mix hardens around the bubbles so the cake stays light and airy once fully baked.img_1933

If your cake mix is still too soggy as the gas escapes (because the gas is escaping early) the sponge around the bubbles cannot support itself and the cake structure will collapse causing a denser, flatter bake. This will also happen if you’ve included the perfect amount of acid but have left your baking around for a while before you get it in the oven – the process will be over before you need it to be.

[Incidentally, the carbon dioxide is not the only thing that contributes to the creation of bubbles in the cake batter. Water from both the ingredients and the bicarbonate chemical reaction will be heated in the oven and start to steam, the steam expands also creating holes in the batter before evaporating.]

If we can understand the basics of how bicarbonate works, the principle will be roughly the same for baking powder

There are several reasons that baking powder is more prevalent in kitchens and more common in recipes:

  • Firstly, on its own, bicarbonate can leave that salty tang behind. It’s difficult to get the exactly perfect ratio of acid to bicarbonate as there are so many contributing factors. These are just a few examples – there could be many more reasons:
    your flour may be slightly damper than the one in the original recipe, causing the reaction to behave differently
  • You may be using a lemon juice or other acid which is more acidic than the original. This may sound odd, but for example any vinegar isn’t just acid – that’d be incredibly toxic and more dangerous than the bleach you put down your sink. Most vinegars are around just 5% acetic acid.
  • Your bicarbonate could be fairly old, have had some exposure to moisture and therefore not be as vigorous
  • All the other ingredients ‘muddy the waters’ as they cannot be relied on to have certain PH values or moisture content and therefore will impact the reaction
  • All these things (plus lost of other factors such as the humidity in your kitchen, how accurate your oven etc) mean that if the original recipe by the chef or cook worked perfectly, yours still may taste of bicarbonate, just because some teensy tiny change, even one out of your control, altered the chemical reaction

For large quantities the risk of that bicarbonate of soda taste appearing becomes greater.
It can actually discolour your baking too: bicarbonate does have a tendency to turn things yellow/green (have you ever put a spoonful of bicarbonate of soda in a glass of red fruit squash? It’ll go a dark purple).

All these things make ‘pre-loading’ bicarbonate of soda with an acid, in a controlled ratio a much more sensible option – hence the development of baking powder.

Baking powder (as mentioned previously) is a mix of sodium bicarbonate and tartaric acid. This means the ratio of bicarbonate to acid is better controlled. By using baking powder, your bake will then be less affected by other ingredients and whether you’re heavy handed with the lemon juice.

In commercial baking powder: this stuff you buy from the supermarket or grocer you’ll often find a stabilising agent in there too such as cornflour (cornstarch) or flour and there may be some other phosphates added (these are harmless).

The cornflour is in there to keep the bicarbonate dry (to avoid any chemical reaction starting), stop it from caking and to help aid the shelf life of the product.

As an alternative, make your own baking powder! You can make it as you need it and it’ll be fresh and ready to start its chemical reaction in your bake.

The ratio is 2 parts bicarbonate of soda to 1 part cream of tartar.

If your recipe calls for 1 teaspoon of baking powder:

2/3 teaspoon bicarbonate of soda and 1/3 teaspoon cream of tartar

If your recipes calls for 1 1/2 teaspoons of baking powder

1 teaspoon bicarbonate of soda and 1/2 teaspoon cream of tartar

You can double up on those if your recipe needs more….

So… why do some recipes need both baking powder and bicarbonate of soda?

This is because they include a very acidic ingredient (or more than one), such as lemon juice or buttermilk, which is needed for taste or consistency. If a recipe has a lot of acidic ingredients it would not be very pleasant to eat if the acidity level wasn’t countered with just baking powder, so the additional bicarbonate of soda is added for that purpose. Of course, this means that the chemical reactions are magnified and give more rise to the recipe, so although a recipe may have both raising agents they probably are not in much higher quantities than a typical bake. Recipes with both in will have been tested and worked out so that there is a balance between ingredient acidity levels, the perfect amount of rise required and the amount of leaveners used all at the recipe development stage.

Conclusions – what does this all mean to the home baker?

If you follow anything exactly in a recipe make sure you stick to the exact amount of baking powder (or bicarbonate) that the recipe states. The recipe developer has worked it all out and tested the bake to ensure it’s correct. Even a little deviation could leave you with an alkaline or acid-tasting bake or one that hasn’t risen sufficiently or, indeed, that’s risen too fast and then collapsed.

Keep some shop-bought baking powder in your cupboard – you don’t always need to make it yourself. Do check the label next time you buy to make sure that anything other than an acid and bicarbonate on the ingredient list is only cornstarch or something you yourself believe to be safe. If in doubt go for a reliable, ethical brand like Dove Farm.

Keep a pot of both bicarbonate of soda and cream of tartar in your kitchen as well. You can then make your own baking powder for a change, to ensure it’s as fresh as possible (to get the best leavening result) or at least now you know how to make it if you run out.

Made a bake and you can taste the soda? Next time you make it reduce the bicarbonate of soda by 1/2 a teaspoon or add in 1/2 teaspoon of lemon juice  (or yoghurt or vinegar etc, dependant on the type of savoury or sweet bake). If the recipe only has baking powder listed just add the extra acid or a 1/4 teaspoon of cream of tartar.

Make sure you keep your tubs of baking powder, bicarbonate and cream of tartar well sealed and away from moisture.

If you’re using chemical leaveners/raising agents get your bake in the oven as soon as it is mixed. While you are mixing the chemical processes are already starting. In order to get the back in as soon as it is ready you should ensure that your oven is up to temperature you require before you start to mix.

Making your own self-raising flour

Self-raising flour isn’t made any differently than plain flour of the same grade: it’s just got the leavening agents already added in. Of course you can get ‘supreme sponge flour’ which is ready sieved  – this just means it’s been fluffed up through a sieve to ensure there are no clumps. If you buy a finer milled plain flour it’s just the same thing as this ‘supreme sponge flour’ just without the raising agents added. Self raising flour is NOT produced differently to plain apart from the extra sieving for the ‘supreme’ flours, but that’s post production and not part of the actual milling. It is only the addition of raising agents (and other extra ingredients as the manufacturers see fit) that makes the difference.

Many well known brands put additional ingredients into their flours other than the raising agents. These are not sinister or harmful but are there to increase shelf life, stop moisture retention, reduce clumping or are just added vitamins and minerals. However, if you make your own self raising flour you won’t need all these – just the bare minimum of ingredients.

None of these additives are harmful or unsuitable for vegans/those careful with ingredients for religious reasons. If you’re not too fussed, then that’s all fine, but personally even though these ingredients are not harmful I do not really want anything that’s not needed. All I need in my self-raising flour is flour, sodium bicarbonate and tartaric acid.

Some of the added ingredients are actually vitamins and minerals, which also seems good but to me I wonder why we need them added to flour of all things. I don’t really expect to get vitamin C from baked goods and I’d prefer it to come fresh from any fruit or veg (I can even ensure I add them into my bakes – that’s a better way to add it!).

Other things you may find on the ingredients label on your flour packet include ‘sodium hydrogen carbonate’. This is just another name for bicarbonate of soda, so of course you’d expect to see that listed.

It is also not unusual to find calcium phosphate, monocalcium phosphate and disodium diphosphate in UK self-raising flour. Calcium phosphate and monocalcium phosphate are the same thing and may appear as E341. Disodium diphosphate is E450. All these phosphates are made commercially from vegan sources and are harmless.

Even though none of these ingredients is a worry, maybe you still fancy making your own self-raising flour? You’ll know what you’ve put into it and it gets you used to making it rather than having to buy two separate types of flour.

Ingredients – self-raising flour

The ratio for self-raising flour is to use 20 parts of plain flour to 1 part baking powder

Therefore, for each 100g of plain flour add 1 level teaspoon of baking powder

(See above for the make-it-yourself baking powder recipe)

Sourdough for starters (or grow your own pet yeast)

Colin2.0.jpg

I recently began a new wild yeast starter as I lost my long-lived one. I have been making sourdough bread since my children started weaning onto solid food, right back in 2001. This post details how to ‘grow’ and look after a wild yeast starter yourself with some tips to keeping it going.

My last batch of wild yeast had been cultivated for several years and my children have helped me to nurture various starters, including that batch. They had learnt about micro organisms, baking and some food science in the process of looking after the yeast, even from a very young age (kitchen science is a great thing to get your kids involved in).

They had also decided to name that last batch ‘Colin’ for some reason, though starters are often labelled as ‘mothers’ and thought of as female (despite not really needing to be assigned a gender!). However, about two months ago I knocked over the lovely glass Kilner jar that Colin had been residing in. It teetered and toppled and then tessellated into little pieces all across the floor.

Damn.

I couldn’t resuscitate Colin – he was covered in shards of glass. He was good too – what lovely bread Colin had helped me create over the past few years. I shed a tear over his passing. I even contemplated making a little chalk line all around where he’d lain to mark where I’d accidentally finished him off.

But life goes on – and so to the rebirth of Colin mark two. Or is that Colin 2.0?

This time I’ve taken precautions. Colin 2.0 is housed in a modern apartment: a nice tall plastic, bounce-able tub. I did stash a bit of him in the freezer before the catastrophe but I made a new batch nonetheless and kept what was left of Colin on ice just in case. Yeast will sit nicely in stasis in a freezer almost indefinitely.

Cultivating your own wild yeast is easy peasy. All it takes is some decent flour, a bit of water, a tall lidded container and a couple of days of patience. Then it just needs a bit of attention every few days and it’ll be happy. I’ve seen “recipes” for starters that include live yoghurt or milk and any number of other additions. You do not need anything other than strong flour, water and something with a lid to keep it in to begin with.

What also puzzles me is that I’ve seen pre-packed starter for sale at alarming prices: if you can’t be arsed to take a couple of days to wait for a starter to begin to ferment, then you’re not going to look after one you’ve paid for. What a chronic waste of money – I worry many people who pay £14 or so for the starter will only make one or two loaves, possibly binning them if they haven’t worked. Another reason to cultivate your own starter, as it’s virtually free – if you go on to love making sourdough bread, fantastic, and if you don’t, you’ve wasted far less money.

I’ve written a previous blog post about the science of yeast, which is of course not written with any scientific expertise, but from what I’ve learnt through breadmaking for years and quite a lot of library researching (to improve my understanding of breadmaking and therefore my bread; the write-up was a happy additional extra). You can take a gander at my science of yeast post: it covers what is yeast exactly, how yeast ‘does what it does’ and looks at what affects yeast during the baking process.

Make your own starter – the ingredient list

You need a tall jar with a lid –  at least 1 1/2 litres. A Kilner jar does the job nicely, but as you’ve just read, this will smash if you’re as clumsy as me. I now use a tall plastic pot with a screw top lid I found in a pound store (result!)

A large ladle full of decent flour. Many sources will tell you to use rye or good wholemeal, but actually a good quality stoneground (organic if possible) strong white bread flour will start you off nicely. Cheaper and easier to get hold of too. This is because it is choc full of complex carbohydrates which yeast loves to eat. Those specialist flours contain less, although they do impart a much nicer flavour. My advice when starting your starter is to begin with good white flour, then as the yeast matures and becomes more vigorous then continue to feed it with rye, emmer, spelt, whatever you prefer to build up that nutty rich flavour.

Water, use the same amount of water as flour every time you ‘feed’ your starter and you can’t go much wrong. There are a lot or arguments about the quality of water – I’d say in the UK as long as you’re using fresh drawn water from the tap (transferred or measured out in a clean container) you should be OK. Elsewhere where tap water is not drinkable or unreliable, then bottled spring water is your best bet.

What to do

In a large bowl, put a ladle (or a half cup full) of flour and the same of tepid water. Whisk it up with a massive balloon whisk or a hand mixer. Don’t worry – it loves it! As yeast is present all around us, in the flour, in the air, you’re practically beating more yeast in.

After a few minutes of vigorous whisking, tip it all into the container and pop on the lid.

The container needs to go somewhere a bit warm (but not hot) and that has a fairly constant temperature. For the last few times I’ve begun a new starter I’ve stuck mine in the airing cupboard.

You now need to wait for the yeast to start its anaerobic activity and begin kicking out bubbles of gas. This will take anything from a day to three or four days. Keep checking your starter every twelve hours.

slashedLeafSourdough
Sourdough loaf: made with sponge method. Wholemeal flour at 55% hydration
Once it’s started to bubble, now is the time for your pet’s first feed!

Your first few feeds will be pretty much the same as all subsequent feeds, although you may want to vary the type of flour you use later and once established the starter needs feeding much less frequently.

Tip in a ladle full of each of flour and tepid water. Mix it vigorously with either a fork or a slim whisk. Put the lid back on and stick back in its warm spot.

You should feed it in the same way for another two days – a ladle full of flour and one of water and a good mix.

After three to four of these feeds your jar will be getting quite full and hopefully very bubbly (like the photo of Colin 2.0 above). Now you can use your starter to make bread!

I’m not going to give you a recipe in this post. I’d actually suggest you try a normal bread recipe first and just add a ladle full of your starter to it, to test the yeast’s vigorousness and flavour. However, you can just dive straight in and make a sourdough loaf with your new pet if you prefer.

Tips on keeping your pet alive

Please note, I look after my starter(s) as someone who only makes a sourdough loaf about once a week (twice at most). This means I am feeding my starter and keeping it’s size in check as I don’t use it that often. For other home and professional bakers who make sourdough very regularly – even daily – they don’t need to temper it’s size or withdraw and discard any starter, as they will be using it up as quickly as they can cultivate it. They’re also unlikely to leave a starter for any length of time (ie when going on holiday) or need to find a way of storing it for future revival. There are plenty of online resources which give fuller instructions for more frequent wild yeast use.

Don’t forget, when making bread with your starter NEVER use it all up or you’ll have to begin from the beginning all over again. Keep a bit in the bottom of the jar and carrying on feeding it.

Feeding your starter should now be about three times a fortnight (when you have it in the fridge – see below) – that is more than once a week, sometimes twice. Use equal amounts of flour and water, about a ladle full of each and whisk it in lightly with a fork.

When you have the wild yeast established and get into a routine of feeding it, you may need to scoop out a little of the starter before a feed if you have not depleted it by making a lot of bread (you don’t have to do this at every feed, just when your jar is getting towards being full). The reasons are twofold: firstly you’ll quickly get much more starter than you need and it’ll fill up your jar if you’re not a very regular sourdough baker. Secondly, it seems to invigorate the yeast a little more if there is a more even ratio between the amount of existing starter and the water and flour you’re putting in – this is just my own cursory observation (I’ve no hard proof) but it seems to me to be more active if it has to work harder.

Slow your wild yeast’s activity down by keeping it in the fridge once it’s got past its first few days, unless you intend to make sourdough every couple of days. The cold inhibits yeast (though doesn’t kill it) so will slow it’s biological process down. It’s now best to not have the lid completely tight on the jar too.

When you want to make a loaf, you need a little prior planning. Bring your pet wild yeast out of the fridge to let it warm, give it a small feed (about half what you would normally – just enough to encourage a bit of vigour) and leave it to get a bit of a wriggle on before you bake with it. Ideally get the starter out and feed it the night before you want to bake, but at least 4 hours before.

If you’re going on holiday you can help your pet survive by feeding it a bit more flour than usual and a bit less water – this drier environment slows the yeast as there is more carbohydrate to eat through but it’s a bit more difficult. This, combined with sticking in a fridge will allow it to last much longer between feeds.

Don’t panic if you’ve not fed it for a few days and it’s all ‘gone a bit watery’. That’s the yeast excreting alcohol as it respires, because it’s run out of carbohydrate (flour) to eat. Just pour this liquid (called hooch) off and then immediately feed the yeast – all should be well. I have (ahem) done this many times to my yeast and it’s always come back well.

I’ve read that if your yeast forms a crust (from lack of feeding) that this can be prised off and the yeast revived easily – I have never seen this so I can’t comment.

Also dozens of sources on sourdough say that if your starter starts to really smell, then all is lost and you should start again as unwanted bacteria has got in. This hasn’t happened to me either, but I would say approach this with caution as if you are new to this sourdough does always smell – however it is pungent but NOT acrid. When your starter has got going and is bubbling take a good long sniff and get used to the smell – you will get this smell often as you bake bread with your starter and get used to it. This familiarity will enable you to detect when it is past all redemption and needs to go down the sink. If it does smell bad then it will be irretrievable and you will have to cultivarte a new starter (and if this is the case I’d suggest a very thorough clean of the jar afterwards, even sterilisation).

Survival techniques

You can save some of your wild yeast as a back up, reviving it in case you lose your starter. To do this your starter should be in a fairly lively stage (ie don’t use it just at the point it needs feeding as it is most weak then). Freezing is my preferred method. It’s also useful to prepare a back up of a starter that is a particularly great batch.

  • Freezing
  • Put a piece of baking paper on a baking tray that is small enough to go in your freezer drawer or compartment. Drop tablespoon-sized amounts of your starter on the baking sheet and flatten them out a little. It doesn’t matter how many you do. Pop in the freezer and once frozen (leave about 4-6 hours or overnight) you can peel these disks of frozen starter off and pop in a freezer bag or container. You can keep this almost indefinitely, but I’d replace with a new batch after 6 months.
  • To revive, place three or four of the disks in a clean, lidded jar and allow it to thaw. Then, once thawed, start to feed it as from the instructions for the ‘first feed’ above. It will only take a couple of days to get your starter back up and bubbly.
  • Drying
  • You can also dry out your starter in a low oven or dehydrator. Again, use a piece of baking baking on a baking tray. This time, spread out a layer of starter across the baking paper. Either pop in a dehydrator (you may need to cut up the baking paper and place smaller pieces in) and follow your equipment’s instructions. If you’re using an oven, put it on its lowest setting, place the baking tray in the bottom of the oven (the coolest part) and leave for an hour. If the yeast isn’t fully dry, turn off the oven and close the door back up. Leave for a couple of hours or overnight. Once dried, crunch up the yeast into pieces and store in a clean jar or container. This again lasts pretty indefinitely but do replace after six months to be sure.
  • To revive, place half a cupful or so of the dried yeast in a clean, lidded jar and add in roughly half the amount of tepid water. Leave to dissolve a little and then go on to the first feeding stage.
  • One benefit of drying yeast, is you can grind it up and use it as an umami powder within some recipes, and it’s a great way with a little water, to create crackle coating for bread.

Enjoy your new pet!

August 2019 – I’ve created a new carb lovers’ area on my Facebook site, if you have any questions you can leave them here in the comments or in this Facebook group area:

Inksugarspice on Facebook – Carb lovers’ group

Why your oven temperature conversion charts could be wrong – and does it matter?

tempIf you’re like me and have an array of cookbooks, some of which have been handed down or been a complete ‘find’ in an antiquarian bookshop or second hand store you’ll find yourself needing to convert weights, measures and, crucially, temperatures quite often.

However, there is a potential problem here: can you trust the values in those old books and does this impact on your modern oven temperature?

If you have a metric oven and are converting from an old Fahrenheit recipe or have an oven in Fahrenheit and a ‘modern’ cookbook with Celsius values (and a Fahrenheit conversion table) you could be setting your oven to a different temperature than the original recipe. Not a potential vast difference but not exact either. Should this be something that you ought to be even bothered about?

Metric temperatures in recipes have been the norm for the last ten to fifteen years or so within the UK. Although Imperial was originally a UK-developed scale (set out in the early 1800s from the previous ‘English scale’ which gave rise to both the British Imperial and the US systems) it seems metric is in the majority use here. Of course, many (mainly older) home cooks still use Fahrenheit and have ovens still with Fahrenheit scales, but they are rapidly thinning out as time goes on and the march of metric continues. We adopted metric with its smaller increments and simpler decimal readings (0 degrees is freezing, 100 degrees boiling water [at sea level]).

For myself, I was taught in metric at school and I measure in metric. I do frequently cook (converting) from old recipe books which only list ingredients in pounds and ounces though. I wondered one day whether I could really rely on the conversion tables and even the accuracy of historical recipes and decided to investigate further. This post has taken about two months of my spare time to research and write up!

The real question I found myself asking, is does it actually matter about the temperature differences?

Very early recipes tended to list oven heat in descriptive words rather than as temperatures, such as ‘low’, ‘hot’, ‘cool’ and ‘medium’. This was because cooking was done on ranges (at best) and over fires (at most basic). When ranges and ovens became more sophisticated and featured gauges to regulate temperature it necessitated a rethink and to list temperature values. Not only were these early gauges not 100% reliable (so that writing down the temperature for a recipe might mean inadvertently writing down the wrong value) there are suggestions that some recipes might have been simply rewritten, changing the words ‘hot’ and ‘cool’ etc to a value, rather than re-making the recipe from scratch in a variable temperature oven and noting down the temperatures. If the writer was a bit relaxed about ‘guessing’ the proper temperature or used someone else’s recipe without checking or testing it to make sure, that mistake could easily be continued on and on as people republished recipes.

Clearly such variations would only have been minor or the recipe wouldn’t have worked and would have fallen out of use. However, some minor discrepancies could have been continued. Ever baked a cake from an old recipe book and thought ‘What on earth did I do wrong?’ It just might be the temperature was inadvertently a little off-kilter for your modern oven.

I can find no solid evidence either way if this theory is true about the guesswork, but it is possible that some recipes were copied and temperatures not fully checked in the past. What we do know is that every oven (even a similar model) seems to run differently and that over time you get to know the quirks of the one you own and adjust the settings or bake time yourself to suit. This doesn’t make converting old recipes any easier though.

Another thing that’s confusing for conversion tables is that Fahrenheit and Celsius have very few comparable whole number values (one of the few easy ones is 210 ° C is equal to 410 ° F). This means recipes either round temperatures up or down from Celsius to the nearest Fahrenheit value, so it’s never exact. If your oven is Fahrenheit then your temperature increments are quite wide; typically 25° or 50°. Metric ovens go up in 10° increments. it’s this difference in increments and the need to round up or down that causes the discrepancies.

While a few degrees hotter or cooler isn’t much of a bother for most cooking, it might make a difference in baking where precise measurements and precise temperatures are stipulated. For instance, cooking a meringue in an oven which is higher by even just a few degrees might result in the dreaded sepia tinge of a too-hot bake.

I’ve written the table below so you can compare the discrepancies between typical cookbook suggested temperatures to match Celsius and what the real equivalent temperatures really are. I looked at 30 plus references and they all gave the same equivalent temperatures (give or take a few errors and a couple of weird ones), so the column with ‘nearest Fahrenheit temperature normally given’ is likely what you’ll encounter in your own cookbooks.

Rounding up or rounding down the numbers

What is especially intriguing in the list of cookbook equivalents temperatures is that 120°C and 130°C both are listed as 250 °F,  and 200°C and 210°C are listed as 400°F. These are examples of the rounding up or rounding down technique, leaving the values to meet somewhere in the middle! Admittedly (even on metric recipes) there can be only a little difference in these temperatures. However I sometimes knock a recipe up or down by 10°C on purpose (such as lowering it to get a slower but more even bake) it clearly does have some small effect on specific recipes.

Is your oven temperature actually correct?

Remember that on top of all this is that your oven might not be at the temperature that matches your dial anyway, especially if it is a few years old!
There is a way to check (roughly) if your oven is running a bit hotter or colder by relying on the melting point of sugar, which is invariable. I will write a post on how to check using this method (watch this space!).

My suggestions/conclusions on whether it matters if conversion temperatures are correct or not are:

  • Don’t worry too much about it – it only matters for very delicate baking or if you have baking OCD (of which I might!)
  • If you do want to bother about it:
    • Just get to know your oven and remember how it cooks different items. That’s all it really needs. My fan oven runs hot (even for a fan oven) and then cooks slightly hotter on the right side than the left. You’re probably already adjusting without realising it because you know your oven
    • Can’t remember how your oven ‘behaves’ or it’s new to you? Jot down how your oven copes with your most common bakes and adjust next time if it cooks a little too fast (turn down by 10%) or too slowly (turn up by 10%)
    • Buy an oven thermometer and look at that – not the dial on the front if you’re really into precise bakes (although I’ve never bothered to have one). It will also have both metric and Imperial values
    • For delicate or precise bakes you may want to think about knocking your oven down or up a notch or altering the baking time when the Fahrenheit oven setting given is quite a way out from the exact Fahrenheit temperature. For example, A low-temp bake which is given as 140°C in a recipe would tell you to bake it at 275°F in the recipe’s conversion table. However, the real temperature you should be baking it at should be 284°F – 9°F hotter. To compensate you could leave the bake in longer or see if you can set the dial a little higher between the set increments
    • When in doubt in baking (apart from bread which benefits from higher temperatures) always cook slightly lower and for longer. This is an especially good rule of thumb for cakes, as it should give a flatter top and a more consistent crumb throughout

Temperature conversion chart


° Celsius
° Precise Fahrenheit conversion Nearest Fahrenheit oven temperature typically given
80 176 – not normally given
90 194 – not normally given
100 212 200
110 230 225
120 248 250
130 266 250
140 284 275
150 302 300
160 320 325
170 338 325
180 356 350
190 374 375
200 392 400
210 410 400
220 428 425
230 446 450
240 464 475

Science of bread making – how yeast works

So, being nosey as usual, after making a batch of spelt walnut loaf I thought I ought to learn a bit more about yeast and the bread fermentation process. I remembered some stuff about yeast from A-Level biology (yeast is one of the most researched and written about organisms going) and I’ve had a batch of sourdough starter yeast on the go for some while, which is fascinating to look at and use. This post is an amalgam of some of the descriptions of yeast and fermentation I’d found both in books, e-publications and websites. I’d urge you to go and look up any specific aspects of this you find interesting for more in-depth information than I’ve given. There’s tons of detail out there (in fact I got rather overwhelmed by the amount of specific information) and it’s really interesting! Oh, and go give your own ‘pet yeast’ project a try by growing a starter dough.

What is yeast?

Yeasts are single cell fungi and there are apparently around 1,500 species of yeast. They are prevalent everywhere, even in the air, which is why anyone can make a sourdough starter.

Only one of those 1,500 species is used for baking and beer making though, and this is Saccharomyces cerevisiae (pronounced sak-ka-roh-my-sees serra-viss-ee-i). The name comes from combined Greek and Latin origins of saccharo for sugar, myces for mould and cerevisiae for ‘pertaining to beer’. Its name represents the way that it thrives off sugar and can be used in the fermentation process for beer.

Although it’s the same species as Baker’s Yeast, Brewer’s Yeast is a slightly different strain. In the past (and you could still do this, if you had access to a brewery!) bakers used to skim off the yeast from the brewing process and use that for their bread.

How yeasts do what they do

Yeasts normally ‘breathe’ (respire) oxygen and reproduce by budding. If they come into contact with sugars (carbohydrates) and are starved of oxygen they start to behave very differently – fermentation.

We can start off fermentation in bread when we mix and knead the dough, as the yeast becomes trapped within the gluten structures and is deprived of air. The dough also provides the carbohydrates the yeast needs. The lack of oxygen and presence of sugars is the perfect environment for yeast fermentation and making bread.

During the fermentation process the yeast’s two enzymes (amylase and invertase) break down the complex carbohydrate molecules in the flour into simpler sugar molecules. The yeast then consumes the sugar and carbon dioxide and alcohol (ethanol) are produced as ‘waste’. If there are more sugars than the yeast needs the result is a sweeter bread – this is controlled by the type of grain used (some grains have more carbohydrate than others) and with the additional of extra sugars in sweet dough, for example, a Kugelhopf or Chelsea buns.

The ‘waste’ carbon dioxide of course isn’t really waste to us at all. This is what causes the rise in leavened bread. The carbon dioxide is caught as bubbles within the gluten strands and puffs up the dough. The alcohol that is given off at the same time gives the dough flavour – a slow rising process (in a cooler environment) will result in more flavour.

So should we be worried that bread has living organisms, carbon dioxide and alcohol? For a start, you’ll be ingesting and breathing in yeast almost constantly, as we explored earlier yeast is everywhere, not just in your bread. Don’t be worried – not only would you not get leavened bread without them, but during the baking process bread the heat will kill off the yeast and evaporate the alcohol and carbon dioxide. All that will be left is the holes where the gas and alcohol had been – which gives you the lovely spongy, holey texture of a well-risen loaf.

Do we need to really knead and knock-back anymore?

A growing movement in baking, spearheaded by a number of bakers including Dan Lepard, Richard Berninet, Mark Bittman etc, is to treat bread with less intervention but more reverently – although this makes it appear that it is a modern technique. This not strictly true, as part of this new philosphy, the autolyse process, was developed and named by Raymond Calvel, a French chemist who, amongst other things, instructed Julia Child on bread as she wrote Mastering the Art of French Cooking [1961] with Simone Beck. However, I don’t think this dimishes the contribution our modern famous-name bakers play, as it took them to perfect and promote such techniques and attitudes that they are now understood and adopted.

For autolyse to occur, flour and water is given the most minimal kneading and/or a folding technique to ensure the incorporation of all the flour and then left to rest to start the fermentation process. This eliminates the ‘hard work’ part of the first few minutes of normal (non autolyse process) knead, and making it easier, however, the autolyse process does need around 20-30 minutes (some say much more). So while it’s less physical work, the bread making will take longer

I went to a session on bread making by a famous baker where he asked why would you knock back all the air that you’ve so lovingly tried to incorporate? I’ve not been able to find out about as yet is how this affects the original explanation of reducing the increased amount of carbon dioxide via the knock-back. As explained below, knocking-back is supposed to get rid of any very large holes – but it seems that without knocking back you don’t necessarily get giant holes anyway. Maybe less kneading means the yeast works slightly less vigorously producing more even (and therefore desirable) holes in the first place? And if you get very large holes, does it matter? Perhaps the carbon dioxide releases during baking or that cutting the loaf and exposing the pockets of gas to air simply eliminates this problem or, simply, it wasn’t such an issue as people thought in the first place?

I’m unclear on all this – I’ve tried many loaves with no knock-back, some or lots of dough-based violence: I can’t conclude anything concrete. I think a choice on how vigorous to knock back actually affects my bread way less than other things like atmospheric conditions, ingredients or especially the type of recipe. I can’t tell you for certain, but I believe a gentle knock back seems to work most consistently and that’s what I tend to stick with.

Why was knocking-back bread used if we want the yeast to make the dough rise?

The thoughts behind using knocking-back are mainly based around the pockets of carbon dioxide gas that fermenting yeast can create during the initial proving process. Huge holes aren’t seen as desirable in a loaf – not great for toast or sandwiches, but lots of mall and medium-sized holes are very de-rigueur now (during the second world war in the UK getting a holey slice of bread felt to people like they were getting cheated out of their bread allowance, so it became imprinted on the UK psyche that holes = bad). Knocking back bursts these larger pockets of aire and helps distribute the carbon dioxide, the alcohol, the yeast and any sugar molecules left through the dough. The process is also supposed to re-activate the yeast, giving it a ‘second wind’ to go on and ferment the remaining sugars, but this is becoming seen as less important now the trend is to left the dough rise sufficiently (but not over rise) in the first place. Typically, the second proving stage after knocking back is shorter because the yeast is exhausted and less vigorous so there is little chance of large holes developing at this stage – but equally less chance of a decent rise if you’ve bashed the hell out of your loaf. Still, done correctly and with a big less vigour the traditional way of making bread still produces wonderful loaves – the trick is to pick the technique to match the recipe and give the no-kneading approach a go to see how it works for you.

What affects yeast

Overwhelming the yeast with salt

Adding salt directly onto the yeast can inhibit or even kill it in extreme cases. So, best to add salt into the bowl after the flour and/or water has already been put in. You can easily reduce the amount of salt in a bread recipe if you are trying to cut down, as salt isn’t part of the fermentation process – it’s only there so you can taste salt in your bread!

High temperatures

A warm room and the yeast will become nice and active. However, too hot and the yeast can’t cope. If you’ve had a loaf that won’t rise chances are you used milk or water (dependant on your recipe) that was overly hot. You can use cold liquids (rather than the warm usually specified) – the kneading process will create friction, and therefore heat, to activate the yeast anyway. Yeast will die at anything around or above 50C (122F). An ideal temperature for yeast is around 30-35C (86-95F).

Cold temperatures

Actually, cold doesn’t kill yeast (well, aparently it does eventually ‘mostly’ die off at about -40C – see Temperature and Life by Herbert Precht). However, less severe cold will slow fermentation right down so keep your sourdough starter in the fridge to stop it being lively, if you’re not making bread that often.

Fresh yeast can actually be frozen in a domestic freezer as the extreme low temperatures put the yeast into dormancy and, after raising to the right temperature, it’ll spring back into life. (There is a caveat on this in that apparently some of the yeast will die off but there will be enough in dormancy to survice to restart the culture). I keep frozen blobs of my starter culture in the freezer, so if I lose my live culture (such as when I go on holiday) I can restart very, very easily. See Sourdough for starters (or grow your own pet yeast) for more on this.

You can safely let a bread rise somewhere fairly cool but it’ll just take longer (probably overnight). Some recipes call for the dough to be placed in a fridge/cool place anyway to slow the fermentation process down and create a more mellow yet deeper flavour.

If you’ve got a cold environment but can’t afford to wait overnight, there are some excellent tips on Epicurious’s Bread Recipes and Tips page – see section 4.Proofing about getting round the cold and speeding up fermentation.

cheseyPaneBianco

The science of meringue making

Cooking is an art, but baking is definitely both an art and a science and few things seem to illustrate the science of baking as much as making a meringue.

I’m no subject matter expert, but I’ve read up on the subject from a number of places – biochemistry books, cookery technique books and various online sources (it helps I work at an University so have access to some good libraries!). While I found quite a lot to go from, there was no one single place with this information altogether. This is then is a baker’s/layperson’s explanation of what’s going on for anyone else who is as interested about this as I’ve been. I’ve tried to check everything I’ve written, including the illustration, and have developed this post to be as correct as I can. If something is howlingly incorrect please let me know (and tell me why it’s incorrect) and I’ll do my best to improve it.

So, how exactly does watery egg albumen turn into snow white, crisp on the outside and gooey-mallowy in the middle meringue? It turns out there are a lot of chemical and biochemical processes going on and there are a few things you can do (or avoid) to help you to get the optimum meringue.

Lower down I’ve explained some of the ingredients and methods that can improve your meringues or cause you problems and looked into any scientific reason behind them. There’s also an explanation of the cooking process – what exactly happens to the meringues as they dry out.

The science-y explanation

Egg white (or albumen) contains almost zero fat, less than 1% carbohydrate (glucose) but around 92% water. What’s left (about 8% of its total composition) is made up of proteins, trace minerals and vitamins. The proteins are the important bit for making meringue. Egg white proteins are long strands, suspended in water that makes up most of the egg white. They lie coiled up individually like tiny balls of wool. This is because each protein hosts two types of amino acid and some are attracted to water (hydrophilic) and some repel against water (hydrophobic) and chemical bonds keep them that way. This means that when the proteins are coiled the water-loving amino acids all sit round the outside closest to the water and the water-hating amino acids hide inside the coiled-up strands to avoid get wet. (I’ve drawn up a very rough representation of what’s happening with the protein strands – please see 1 in the drawing).

Representation of what happens to protein strands in egg white - from 1. their original form, through 2. denaturation from whipping to 3. coagulation when whipping is complete
Representation of what happens to protein strands in egg white – from 1. their original form, through 2. denaturation from whipping to 3. coagulation when whipping is complete

The proteins will stay in this form unless they are subjected to physical stress, certain chemicals or heat and the incorporation of air. We’re interested in the physical stress option for a typical French meringue – beating the hell out of the egg white with a whisk. [Italian and Swiss meringue methods introduce heat stress to the mix as well, which causes thermolysis (where the heat causes the proteins to pull apart). Italian meringue recipes include pre-heated sugar syrup and Swiss meringues are made over a bain-mairie (hot water bath).] When you beat egg white you cause the break-up of the chemical bonds that keep the protein strands together. This is called denaturation. By whisking you also start to incorporate air bubbles into the egg white that the hydrophobic amino acids become attracted to and this also encourages the proteins to unravel from their natural curled-up state.

These two stress processes cause the coiled-up protein strands to un-curl and turn the egg white from a liquid into a foam. The chemical bonds that hold the protein strands together break and the hydrophobic amino acids start to attach to the bubbles of air you’ve whipped in, holding the air in place and keeping the foam structure fairly intact. (See 2 in the drawing). The final part of this is coagulation, where the protein strands, attached to air bubbles by the hydrophilic amino acids, start to bump together and create chemical bonds with each other, creating a sort of mesh-like structure. This keeps the air bubbles locked in place and supports the foamy composition of the whisked egg white. (See 3 in the drawing).

The three states often cited for whipping meringue – soft, firm and stiff peaks – relate to how much stress the proteins have been subjected to. Less stress by whipping (and therefore also less air) leaves the protein strands less untangled so they can’t bond together quite so effectively. This means the foam structure is not so strong, giving softer peaks. The more you beat it applies higher stress and more air so the stiffer the foam will be. This is because you will really straighten out the proteins, so they are fully open to being in contact with other strands and can create new chemical bonds around larger air bubbles. But beware – there is a limit to the stress you can apply and egg white can be overwhipped. Proteins can be stretched too far, become unstable and collapse, releasing the captured water and air. This results in a flat meringue where seconds before it was beautifully fluffy. There is a remedy though – please see below.

Ink Sugar Spice blog https://inksugarspice.wordpress.com/

Adding sugar

Added sugar dissolves into the water molecules in the egg white and this actually increases both the strength and elasticity of the whole mix, and helps support the proteins from stretching too far and collapsing. This, in turn, allows a little more air to be whipped in making the egg whites even fluffier. Sugar needs to be added after the stress process has already started – so never, never add sugar before you start whipping. If you add sugar first it will have the opposite effect to what you want and will prevent the protein strands from uncurling. Because sugar is there to dissolve with the water molecules you should give it a fighting change and use the finest caster sugar you can get. Some recipes even list icing (confectioners) sugar.

Ink Sugar Spice blog https://inksugarspice.wordpress.com/

Four things that can help a meringue

1. Using fresh eggs

It’s best to use only the freshest eggs that you have for meringues. Fresh egg albumen has a high acidity level, and this level drops sharply as the egg ages. Acid in the egg white will slow down the coagulation process (where the un-curled protein strands bond with each other), which gives you more time to beat in air, it will seem harder but it’s definitely worth it for that perfect meringue. I’ve seen a few places which suggest that you should use older eggs because they are easier to whip up to a foam. In older eggs the chemical bonds in the proteins have loosened, making it easier to beat in air and so get a foam more quickly and with less effort. However, it’s a false economy because once whipped up they will not coagulate fully due to those relaxed chemicals – the bonds won’t reform with any adherence. This means you’re less likely to get really stiff peaks, the meringue will sag and loosen and it will be less likely to have a nice crisp shell as it will stay slightly sticky. So use fresh eggs for the best results. That said, while you should still avoid eggs that are getting close to their ‘use by’ date, you can get away with eggs that are a few days old by employing the next tip…

2. Adding white wine vinegar, lemon juice or cream of tartar

Some people swear by adding one of these ingredients in the meringue mix. They may not know why they work or may think that it just makes the meringue more ‘glossy’. The real reason that these work as an extra ingredients is because they all increase the acidity level of the mix, mimicking the same effect as using the freshest eggs. It’s better, though, to just to use the freshest eggs as something made with the fewest ingredients is preferable and it also just slightly alters the flavour (especially the lemon juice – but then you might want that for your recipe). However, if your eggs are a few days old, it’s worth putting in a half a teaspoon of white wine vinegar (my preference out of the three ingredients) to help. Having tried all three ingredients my least favourite is cream of tartar as it definitely results in a slightly drier and crispier meringue. I prefer my meringues to be more gooey on the inside, but if your preference is for crispy it may be the extra ingredient for you. If using, you must add the extra ingredient after you’ve incorporated the sugar.

3. A metal or glass bowl

Any metal or glass bowl is just easier to wash and keep grease-free than a plastic one. However, I have read in several places that there is a specific benefit to using a copper bowl – see below. However, I can’t imagine anyone other than a professional pâtissier using these as they are just so expensive.

4. Copper

Copper molecules actually bind with one of the proteins in egg white. This binding causes a reaction that tightens the chemical bonds between the strands, resulting in a stiffer and less prone to collapse foam.

Ink Sugar Spice blog https://inksugarspice.wordpress.com/

Five things that can cause problems

1. Fat

Any fat present will make the denaturation process more difficult. It’s not impossible to whip a meringue where some fat is present, but it will take a whole lot longer – so long it may not be worth trying! Anything more than the smallest amount of fat and it will be impossible. One way to ensure the bowl is scrupulously clean is to rub it with the cut edge of half a lemon (this also adds a little of one of extra ingredients listed above that can help with the meringue mix).

2. Plastic bowls

It’s not the plastic itself that will cause you grief, but the fact that plastic attracts fat and it’s more difficult to complete clean a plastic bowl free of grease than most other materials. So, avoid a plastic bowl if you can to give yourself an easier task. However, if you’ve only got a plastic bowl, clean it with very hot water, wipe it bone dry with a kitchen towel, maybe wipe over a cut lemon and apply a little extra effort. If it’s clean, it will still work.

3. Dirty utensils (beaters, whisks, spatulas etc)

As with bowls, make sure your utensils are scrupulously clean. Any residue or grease on them will affect the denaturation process and stop you from getting a fully fluffy mix. Wash in the hottest water posible and leave to dry out or dry with a kitchen towel.

4. Egg yolk

The reason you need to separate out the egg yolk intact from the egg white for meringues again is because of fat. Yolks have a high fat content. With the teensiest amount of egg yolk in it’s still possible, but as with the comments for plastic bowls, you’ll need to whip the meringue for a lot longer and a lot harder. Anything other than a minute amount of yolk and you should just start again separating the eggs out – save the original whites and yolks for something else.

5. Eggs from the fridge

It’s best to have room temperature eggs for making meringue, as the bonds holding the protein strands in curls will already be slightly weakened. Room temperature eggs are already going through a very mild occurrence of heat stress (or ‘thermolysis’ as mentioned earlier) which will lead to denaturation. It just gives you a head start.

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The cooking process

Actually, meringues are less ‘cooked’ than actually just ‘dried out’. In your carefully whipped and very fluffy meringue, water and air bubbles are held in the foam. Think of how a sponge looks – a framework of material around pockets of air and water. All you need to do to a meringue is heat it enough to tighten the chemical bonds in the protein strands (to finalise coagulation) and to evaporate the water, leaving the framework intact.

Cooking/drying out slowly with a low heat also enables the proteins to coagulate together in an even way (it gives them time to ‘settle’), ensuring the structure of the meringue is perfect. Use a low temperature (a max of about 120°C for a conventional oven or 100°C for a fan oven) to remove the water and ensure the best bake.

In fact, you can actually dry out a meringue by putting it in either a very low oven (80/60°C) for a few hours or an oven that was heated and turned off as soon as you put the meringue in; just leave the meringue in overnight or for about six hours in this case.

I’ve given a recipe for French meringue in another blog post, plus it has some explanations on how to check if your meringues are ready and what you can do if things have gone a bit wrong.

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Holy basil and strawberry pavlova - learn about meringue making and the science of meringues on Ink Sugar Spice

French meringue recipe and ‘meringue 101’

 

Pavlova2Please also see my post about the science of making meringues, which has tips and explanations to ensure the best meringue possible. It explains what actually happens to the proteins and amino acids in egg white during whipping and cooking, plus some useful stuff such as why lemon juice or white wine vinegar is sometimes added to the mix, why it’s said you should avoid plastic bowls or why sugar shouldn’t be added before whipping the egg whites. See lower down in this post for some hints and tips on ensuring your meringues always work in a problems/FAQ section. You’d think there wouldn’t be many recipes for meringue, as there are so few ingredients, however there are many variations of egg white to sugar, what type of sugar to use and the inclusion of extra ingredients. You should roughly work on about 50g of sugar to one egg white, plus a little extra ‘for luck’. I’ve tried and tested many combinations in the past and the following recipe that I’ve hit on is one that has been pretty fool-proof for me.

Notes

This recipe is enough for about 26 small meringues, 14 medium, a Pavlova or pie topping.

Ingredients

  • 3 large fresh egg whites, free-range preferably
  • 175g caster sugar (fine white if you want classic meringues or unrefined golden caster if you like the taste and want a golden-y meringue)
  • 2 teaspoons vanilla extract (the type with seeds) or the seeds from ½ a vanilla pod
  • an optional extra (pinch of cream of tartar, ½ teaspoon white wine vinegar or ½ teaspoon lemon juice) if you want or if your eggs are more than a couple of days old

Method

  1. Preheat the oven to 120°C (conventional) 100°C (fan)
  2. Whip up the egg whites to soft peaks and slowly tip in the sugar in small batches (about a tablespoon full at a time) while still whipping. Continue to whip until you have stiff peaks.
  3. Add the vanilla and whip a little more until the vanilla is thoroughly distributed.
  4. If you are using one of the extra ingredients (I’ve explained their use and the effect they have on the meringue mix in my science of meringue blog post) add it now and whip again, a little more to ensure it is incorporated.
  5. You can test the readiness of the meringue mix by pulling the whisk out of the mix – the little bit of meringue that’s left on it should stay up as a peak if you hold the whisk pointing upwards. If the meringue flops it needs some more whisking. Alternatively, you could do the ‘bowl upside down over the head’ trick, but that’s a bit over the top when you’re in a kitchen on your own – and you could end up very messy if you hadn’t mixed it enough yet!
  6. Pipe or spoon the meringue onto a parchment-lined baking sheet.
  7. Bake for 40 mins. Turn off the oven, bake for 40 mins more. [Alternatively, turn off the oven as soon as you put the meringue in and leave in overnight]. (See the blog post about the science of meringue as it explains how meringues dry out).

Problems – or ‘meringue 101’

How do I tell when the meringue is ready?

French meringues are perfectly cooked when they are still white but sound hollow when you tap the bottom (the only reservation to this is if you’ve used unrefined caster sugar which would keep a slightly browner colour of the meringue naturally). The meringues will peel away very easily from your baking paper once they’ve fully done.

My meringue was OK but has now gone flat while whipping

You’ve over whipped your meringue and the proteins have stretched too far, collapsing the foam. Add in one new egg white and whisk again – this can resurrect the meringue.

Is it warm and humid? Or is your kitchen steamy from a kettle or something you’ve got cooking? A (very) high humidity will soften the meringue mix as it introduces too much moisture (you only need the water content that exists in the egg white already). You may need to abandon making meringues for that day or mix up the meringue in another room, if your kitchen is steamy.

My meringue won’t whip up

If you put the sugar in before you started whipping you’ve blown your chances. You’ll need to start again. Another reason is that you’ve got some fat/grease in the mix. You can either start again if you think you’ve got a lot of fat/grease in there, or if there’s just a little chance that if you give it another few minutes of whipping it may be salvaged.

My meringue has a watery layer/is “weeping” (when making a meringue on a filling, such as a lemon meringue)

This is because you put the meringue on to a cold filling. If you put it on while the filling is hot this starts to dry out the meringue straight away, rather than allowing the water in the meringue to start slowly leaking out as the meringue foam starts to disintegrate over time. (Cooking the meringue fixes the protein strands in the egg white into position – coagulation – so when the water evaporates the structure is still in place. If the meringue stands before being cooked the strands aren’t so strongly bonded together and will begin to collapse, allowing the water to leak out of the bottom rather than evaporate in a warm oven).

My meringue shrank leaving a gap between the edge of the meringue and the pastry (when making a pie/pastry)

Because drying out (cooking) the meringue causes the water to evaporate and the protein bonds to coagulate fully, there will be a little shrinkage in the structure of the meringue. (Although some of the methods listed above will minimise any shrinkage by keeping the structure as firm as possible, eg whipping in a copper bowl strengthens the chemical bonds during coagulation). You can counteract any shrinking by ensuring that the meringue seals to the pastry edge. Meringue is quite sticky before it’s cooked it should ‘glue’ quite well. Just spread it out so it touches the pastry the whole way round.

napoleons made with chocolate puff pastry - Ink Sugar Spice

Maths, algebra and making puff pastry

Me and maths aren’t usually friends. But I’ve been intrigued to find that there’s a lot of maths that can explain the fluffy lightness of rough puff and puff pastry.

The folding method and total number of folds for puff pastry is crucial to creating the many layers. Mille feuille means thousands leaves in French, and it’s literally possible to create more than a thousand (2187 to be exact) in just 7 ‘turns’. Although making 6 turns, or 729 layers, is usually the norm for recipes.

The process of building puff pastry is to roll out into a rectangle and fold the bottom third of the middle third, then the top third over the other two, and then turning 90˚ (or -90˚ – it doesn’t matter as long as you’re consistent throughout) as in the image below. This process is one ‘turn’.

The first turn makes three layers from the initial rolled out sheet of pastry.

Turn two or more is where the maths comes in as every turn creates three layers out of the pastry block you already have.


For the first turn: it’s 3×1 making 3 layers.

For turn two: you’ve already got three layers so when you do the folds the layers are mutilplied 3×3 or 3 which results in 9 layers.

I’ve drawn a sketch to show what’s happening a little more clearly…

Illustration by Ink Sugar Spice on the number of layers of puff pastry created at each turn when you make it yourself

For turn three: its 3 x 3 x 3 or 3 x³ giving 27 layers

For turn four: it’s 3 x 3 x 3 x 3 or 3 x⁴ giving 81 layers

Four turns is good for rough puff pastry. Most pies can be made with rough puff, such as apple pie or tart tatin. Eccles cakes and apple turnovers are also made with rough puff.

For turn five: it’s 3 x 3 x 3 x 3 x 3 or 3 x⁵ giving 243 layers

Five turns is totally fine for puff pastry, but as pastry is normally rested in the fridge after every second turn made (ie on an even number of turns) it’s normal to keep going for one more turn.

For turn six: it’s 3 x 3 x 3 x 3 x 3 x 3 or 3 x⁶ giving 729 layers

Six turns is the classic number for a very flaky yet still manageable patisserie bake.
You can see how quickly the numbers have added up!

Seven turns is a really extreme and would give 2,187 layers with 3 x 3 x 3 x 3 x 3 x 3 x 3 or 3 x⁷

You’d normally get to six turns only for puff pastry. Some very delicate patisserie recipes call for seven turns but it is so fine you do risk tearing the pastry.

napoleons made with chocolate puff pastry - Ink Sugar Spice
Napoleons made with 6-turn chocolate puff pastry
chocFeuilletage_7
Chocolate puff pastry – see Feuilletage chocolat / chocolate puff pastry