A small Miche
Slowing down bread staling and the magic of toast
This article looks at bread staling and how we can slow it down. Also how to recover good bread from a staling loaf.
The technical term for bread staling is Retrogradation. I use the more familiar term of staling here.
I see videos of people making large loaves of French Miche bread. Miche, pronounced Meesh, is French for Round. These loaves were traditionally baked once a week when the communal wood fired ovens were fired up and the big round loaves were said to have lasted a week.
They were originally baked at a time when households might have had at least a dozen members. They were big loaves which could well weigh quite a few kilos. It’s a lovely image, but wouldn’t those loaves have been pretty stale by the end of the week?
Let’s see.
What is bread staling?
Quite simply the starch in a fresh loaf is distributed throughout the loaf in a loose bond with the loaf’s water. It is gelatinised, jelly like,soft and moist. Bread staling involves the starch clumping together into chains of starch crystals. These require a lot of water to form. So crystallising starch takes the water from the loaf to form their hard crystalline chains. These crystals lock up the water which is why a stale bread seems dry. When we heat a stale loaf it drives the water back out of the starch crystals and the starch again becomes gelatinised. However, given time, the starch again begins to crystallise and the staling process begins again.
Quite simply we want to stop the starch from crystallising. In order to form crystals the starch has to clump together first. It does this by using the water in the loaf as its transport medium, to gather into crystalline chains. The starch moves through the water. As we shall see later, this water transport as a medium is important.
Slowing down staling
High Hydration Doughs
The more water there is in a loaf the faster the starch can move and form crystalline chains. This is the downside of high hydration loaves. There is more water so the bread can stale faster. The advantage of high hydration loaves is that they form a more open crumb. The baker must make choices about how much water to use in their loaf. High hydration doughs are not always the best choice. If you want a good shelf life for your loaf, use less water in the dough.
Staling and Fats
Fat coats the starch in the dough. This coating makes it more difficult for the starch to absorb water in order to crystallise. I have written about the use of fats in other articles. Different fats have different effects on the dough.
However, any fat will slow down the starch crystallisation and give the loaf a longer shelf life. 2% - 3% of the weight of the flour in fat. More fat will not slow the water absorption further.
Cooked flour, Scalds, Tangzhong, Yudane and Roux.
The starch in dough is held captive in packets. These are often referred to as starch packets. When we scald flour the heat ruptures the starch packets and the starch inside is released and it then becomes hydrated and gelatinised. Starch in this form binds tenaciously to water. This free floating gelatinised starch is less prone to starch crystallisation, that is it resists staling. A loaf made by scalding up to about 30% of the flour, by weight, will stay fresh for about three to four days longer than one made without scalded flour. Remember though that scalding flour also cooks the gluten in it. That gluten is no longer available to trap the CO2 made by the yeast. Scalding too much of the flour will make for a denser loaf. Scalding about 20% of the flour is typical.
Organic acids and yeast
A bread baked only using yeast can stale in as little as twenty-four hours.
As bread ferments organic acids are formed by the yeast. These acidic compounds hold on to water which again denies the starch some of the water it needs to migrate to form crystalline chains. Yeast produces organic acids quite slowly. These acids are also involved in other reactions such as forming bread flavour. This is why cold fermentation is so effective with yeast only breads. These slow reactions get the time they need in the fridge to produce bread flavour and the yeast gets more time to develop more acids, which slows the staling process. Even without using cold fermentation in the fridge, using a little less yeast and fermenting the dough for longer will develop more organic acids giving the loaf more flavour and a higher resistance to staling.
Organic acids and natural leavens.
Natural leavens are also called Sourdough Leavens.
The Lactobacilli in natural leavens produce higher levels of organic acids than does yeast on its own. They are therefore much more effective at producing bread flavours and slowing staling. A naturally leavened dough will easily stay fresher for a few more days than a yeast only bread. Natural leavens do not have to produce sour, sourdough bread. That level of sourness (acidity) comes from how the natural leavens are managed. My natural leavened breads are not at all sour and they still have a 4-5 day shelf life.
Bran.
Bran is the outer roughage layer to the grain kernel. It is bran which, when left in the flour, gives us our wholemeal flour.
Bran is hygroscopic, it absorbs and clings on to water. Adding some wholemeal flour to your dough will deprive the starch of some of that moisture it needs to migrate and form starch crystal chains. It also keeps the bread a little more moist, for longer.
Sugars
Sugar is also hygroscopic. It attracts and holds on to water. It is not as effective as a scald, but a little sugar, honey, or malt syrup will decrease bread staling a little.
Sugar used at 3%-5% of the weight of the flour will slow bread staling a little. 8% sugar is regarded as a maximum for savoury breads. Because sugar holds on to water, using too much prevents gluten formation as that process requires the water that is tied to the sugar.
Preventing Fungus growths in humid climates
The organic acids mentioned above will give some protection against fungal growth on bread. Natural leavens are the most effective prevention because of their higher acidity. However, some people prefer to bake only with yeast. In that case a cold fermentation period in the fridge will develop some acidity which slows fungal growth.
If baking only with yeast we could consider the commercial baker’s choice of adding acids to the dough to control fungal growth in storage.
Vinegar can be used at up to 1.5% (by weight) of the total flour weight. More than that can make the bread taste vinegary.
Citric Acid has less flavour than vinegar and it can be added at up to about 1 gram per kilo of flour. As most domestic scales are only accurate to 1 gram either way, it is best to add say 10 grams of citric acid to 90g of water and then add 5g of the solution for every 500g of the bread flour in the recipe. Keep the remainder in an airtight container in the fridge.
See also Bread Storage, below, for things to avoid regarding fungal growths.
Re-baking bread
In fancy households this is called réchauffé (pronounced ray-show-fey), it is reheating in French. It makes that two day old casserole in the fridge sound a lot better, Chicken casserole réchauffé?
Simply mist the loaf heavily with water and put it into a 200C (393F) oven for 10 – 20 minutes. A baguette heats through quicker than a tin or pan loaf and so ten minutes is about right for this. The pan loaf will need nearer to fifteen, or 20 minutes to heat through enough to drive the water out of the starch crystals.
The heat drives the crystallised starch back into its gelatinised form releasing the water it locked up when it crystallised. For a little time, at least, the bread is again fresh.
Twice baked bread (Rusks)
To make this the loaf is baked and cooled. It is then sliced and the pieces are put into a warm oven at about 160C / 320F until it is toasted and completely dried out. Counter intuitively it will now stay fresh for weeks, or even months in a dry atmosphere. This is because there is too little water for the starch to use to migrate and clump into crystals. Also there is too little water left to form the crystals. It is also too dry for pathogens and fungi to grow. This is the principle behind hard tack, or ship’s biscuits.
Freezing bread
Some people slice their bread and freeze it, taking the odd slice and thawing it when it’s wanted. When the bread is frozen the ice is solid and the starch cannot migrate and form crystals. The slices remain fresh. So too does a whole loaf.
Bread freezes exceptionally well. So much so that my toaster has a setting for putting slices of frozen bread straight into it.
Storing your loaf
If the loaf is wrapped to keep it moist it will stale faster than if it is left uncovered and allowed to dry out a little.
I won’t repeat the part about water and starch using the water to migrate and form crystals, yet again. That drying out slows the staling process by reducing the available water. Keeping your bread moist will speed up staling.
Staling is about starch crystals forming. As they form they absorb a lot of water, which is why older bread has a dry mouthfeel. Bread drying out is simply loss of water into the atmosphere which is not staling and the bread remains more edible.
Placing the bread in plastic bags traps a moist atmosphere around the loaf and this is an ideal environment for fungi to grow.
Some folk put their loaves in a cotton bag to allow it to breathe a little, which slows the loaf drying out. This will keep a sandwich loaf a little more moist, but it will also speed up staling a little. Though the cut end becomes a problem. Bread crust allows a lot less moisture to escape than the cut end of the loaf. Some folk keep the crust and pop it back onto the end of the cut loaf after each slice is taken.
Free form loaves, like French boules and bâtards, are better sat on a wooden board cut face down in a cupboard rather than an enclosed bread bin. The cupboard allows a little more air circulation than does a bread bin and the wooden board allows moisture to dissipate, a little, from the cut face, but it also stops it drying out too. Placing the cut face down onto plastic can encourage fungal growth because of the trapped moisture makes a humid area. Bread bins, unless they are large, don’t allow for much air movement and this can cause fungal growth.
Toast
By now it is obvious that toasting bread re-gelatinises the starch crystals. Making a stale piece of bread moist and fresh again.
The other thing that occurs is that the surface is subjected to browning. Just the same way a crust forms and browns when we bake a loaf in the oven. The technical term for browning is the Maillard reaction. Maillard was the first person to work out the chemistry taking place as a food browns. For our purpose all we need to know is that the high heat makes the sugars and proteins, on the surface, react together to form those wonderful flavours and the brown colour. The magic of toasting stale bread is that the interior of a piece of toast contains hydrated (non crystalline starch) whilst the outside now has a Maillard-flavour-rich layer. The browning occurs between 150C-160C., or 302F-320F.
Let us not spoil this by talking about the added acrylamide caused by browning. It is carcinogenic. Just don’t burn your toast.
Back to that big Miche loaf
If it was made with a natural leaven, or beer barm, which is also acidic, then it might well have lasted fairly well.
Add to that the traditional Miche would be either wholemeal, or have ‘not so much’ white flour in it and the bran would have given it a longer shelf life too.
Maybe it wasn’t quite that stale come the next weekly bake day. Though I do expect that many a toasting fork was used.
A naturally leavened bread, or a bread with a scald, can quite easily keep for four to five days. Then, as they say, it’s toast.
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