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Hello Reader,

As mentioned in my previous edition of the newsletter, over the next few months we will be learning about:

what happens during the bread-making process
how crops science is being used to make better bread
the nutritional aspects of bread

TL;DR

Yeast was first commercialised for brewing beer.
The 4 basic ingredients of bread are: flour, water, yeast, salt.
The magic of the bread reaction starts when water is mixed into the flour.
Enzymes breaks down the sugars for the yeast and bacteria to create the gases that make bread rise.
Keeping bread in the fridge makes it go stale faster.

The idea for this topic came up because of lockdown baking. Last year, when we had the 8-week long Circuit Breaker, I remember not being able to get any of the ingredients to bake because it was all sold out.

Now that I’m learning how to bake bread, I went down the rabbit hole of bread science to share with all of you.

History of bread

Bread has been around for a very, very long time. So far, the oldest evidence of bread dates back to 14,400 BCE, from the archaeological dig site in northeastern Jordan called Shubayqa 1.

All across different cultures, bread has been a staple. It comes in many different forms, shapes, sizes, leavened and unleavened. At this current moment, we don’t know if the bread-like artefacts found in Jordan are leavened or unleavened bread.

There are 2 ways to create leavened bread. The first way is to use commercially produced baker's yeast. This type of yeast is pure. Which means that it is not mixed with other types of organisms. And these are used by mores bakers and bakeries(1).

History of yeast and commercial yeast production

Yeasts are microscopic, single-celled organisms. They feed off sugars by breaking them down into carbon dioxide, alcohol, and molecules that give you flavour. This process is known as fermentation (2).

The word yeast derives from Late Old English gist, derived from the Middle German words gest, meaning dregs or dirt, and jest, meaning foam, as well as the Old High German word gesan/jesan, meaning to ferment (1).

Yeast has been used in bread as early as 1300-1500 BCE, in Ancient Egypt. In fact, the use of yeast, and the species of yeast used in bread and beer, originated from China before it was spread to the west 14-16 thousand years ago, via the Silk Road.

Yeast was first 'commercially' produced in the 1700s, mostly for the use in beer brewing than for bread-making. These 'commercial' yeast came in fermented hops, rye and malt. They were pressed together to make blocks. And these blocks only contained as low as 6% yeast. It was these beer dregs or the yeasty foam from beer brewing that was used for baking bread.

The first commercially sold dried yeast for baking was sold in Vienna, in 1822. The first patent to create a sterile environment to culture yeast was by Alfred Jorgensen and Axel Bergh, in 1891. They created a sterile aeration system to grow and maintain the yeast cultures. The yeast was mostly used for brewing as Axel Bergh owned several breweries.

The second way is to use a 'starter', which is produced by allowing the naturally occurring yeast and bacteria in the environment. The starter is used to ferment in the mixture of flour and water. This starter is then used as a leavening agent for sourdough bread making.

The yeast used in sourdough is different. It is not cultured commercially and comes from the air, the flour and the hands of the baker. This is termed wild yeast. The wild yeast cannot break down maltose the same way the commercial yeast does. It needs the help of the bacteria in the sourdough to break it down for them. The same bacteria will feed on the dead yeast, and creates lactic acid that gives sourdough the sour flavour (3).

Sourdough starters usually begin with adding water and flour together and then just allowed to stand at room temperature. This will allow the yeast and bacteria present in the flour and water mix, to start fermenting the mixture. Most of the microorganisms in the starter are originally on the flour itself, and in the air and dust where the starter was first made.

Some of the bacteria and yeast in the starter also originates from baker's hands and their environment. Because of the different mix of bacteria and yeast between each kitchen and baker, this influences the flavour of the bread they make. This would be why the loaves of bread from different bakers may taste slightly different from each other, even though they use the same recipe(4).

Chemistry of Bread-making

Now that we know about the history of commercial yeast, and the difference between cultured yeast and wild yeast, let’s look into what happens when you add water into the mix.

The 4 main ingredients of bread are made up of :

Flour
Water
Yeast
Salt

There are basically 4 steps to making bread:

Mixing
Kneading
Leaving to ferment
Baking the bread

Mixing

When water is added to flour, this process is called hydration. This starts some chemical reactions that are very important for bread making.

The water will activate the protein, and this starts the enzymatic reactions, as well as gluten formation. Gluten is made up of proteins called glutenins and gliadins (3).

Kneading

When you start kneading the mixture, the protein gets activated. The proteins form bonds and chains. The more you knead, the more the protein gets loosen, the more the protein will interact with each other and form more bonds (3).

Gluten has a very important role in the process of making bread rise. Gluten traps the gases. Kneading the dough also helps to make the gluten matrix, plus, making sure that the carbon dioxide bubbles are evenly distributed throughout the dough (5).

Usually, the kneading process of making dough will help in the formation of gluten. However, in no-knead bread recipes, it's the enzymes that do all the work. The enzymes will break the gluten proteins into smaller pieces.

The small pieces of gluten protein will be pushed around the dough mixture by the movement of the bubbles of gas that yeast produces during fermentation. So this takes the place of kneading. And that is why no-knead bread needs that length of time in the fridge or on the countertop to create the same kind of dough as the regular kneaded dough (2).

Fermentation

It is during the fermentation process, that’s when the magic happens. One of the major gasses in making bread rise is carbon dioxide (CO2). That is why the dough increases in volume (2).

In unleavened bread, the source of CO2 is the reaction between the sodium bicarbonate with the acidic ingredients or conditions in the dough. In the case of leavened bread, CO2 is produced when the sugars are broken down by enzymes and the yeast.

An enzyme is a molecule that is usually large and made up of protein, that increases the speed of a reaction. Because enzymes are activated when water is added to flour, bread doughs with higher water content (higher hydration), will ferment faster as more enzymes are able to move around the dough to break down the substrates that help with fermentation (6).

One of the first enzymes to start a reaction when water is added to flour is amylase. The amount of amylase in the flour depends on the weather and how the wheat was harvested. So to make sure the quality of the flour is maintained, the flour mills will test to see if they may need to add more amylase or blend it with other flours to reduce the amount.

What amylase does is break down the starch chain in the flour, into maltose. Maltose is a type of sugar with 2 glucose rings. Yeast in bread doughs need sugars with a single glucose ring to start fermentation. So they use the enzyme maltase, to break down the maltose that the amylase enzyme had broken down earlier, into sugars that they can use.

Protease is another enzyme naturally occurring enzyme in wheat that the flour mills will check for. They will check if they need to add more protease to increase or decrease the amounts to the industry standard. Protease breaks down the bonds between amino acids. Too much protease will break down the gluten in the dough, making it too soft. Just enough will allow the dough to be just soft enough to work with. Because the protease takes time to work, that is why the resting time between kneading is important (6).

All the above processes involved flour, water and yeast. What about salt? Salt ions help to stabilise the gluten structure, so you have a stronger and more stable dough. Without the salt, the dough you get will be sticky. Salt strengthens the bonds between the proteins, making the dough elastic. And it adds flavour to the bread too! If you’ve ever made under-salted bread, you’d realise how important salt is.

Baking

Now that you’ve mixed and proofed and shaped the dough. What happens when you bake it?

When the dough is baked, the heat from the oven expands the CO2 further, so the bread rises even more and sets(2). That is why even a small bun can grow up to twice its size during baking. The remaining sugars that aren’t broken down by the yeast undergo another chemical reaction called the Maillard reaction. This gives us the browning on the crust that we associate with bread(3).

Now that we know that the basic ingredients of bread are made up of just 4 ingredients, why do we see commercially made bread have more ingredients, specifically additives? Additives are added to bread as a way to make the appearance more appealing, regardless of the ingredients used. This was a way to make it cheaper. This was so that they could make bread that was soft and nice, even if the wheat they used were lower in protein.

Traditionally, it takes a lot of time to make bread. It took 3 hours for the dough to rise the first time, and then "knocked down" to remove most of the gases. The dough is then portioned out to then proved a second time. To cut down the amount of time, some bakers add more yeast to increase the gas formation and, and oxidising agents like ascorbic acid, which will help in gluten formation(5).

So additives aren’t necessarily bad. They are just added so that commercial bakers can make more bread, with less time, and the same nice quality. Though I do recommend that you read the labels, in case you are allergic to any of the ingredients.

Can bread stay fresh longer?

We all know that the bread goes stale after a few days. What causes it to go stale? During baking, the heat breaks down the microstructures made from a type of sugar called amylose. Over time after breaking, the structure reforms into a crystal form that contains a lot of water. These structures reduce the amount of 'free' water in the bread, making the bread less springy and appears dry out. This is what we see as stale bread.

Putting it in the fridge makes it go stale faster. As fast as overnight! But if you leave at room temperature or in Singapore weather room temperature (30°C-34°C) in an airtight container, it can remain soft for up to almost a week!

Adding fats to the dough will improve the texture and the volume of the bread as the fats, being hydrophobic (afraid of water) slows the movement of water during the reformation of the crustal structure. This keeps the bread moist for longer and stays 'fresh' for a longer period of time. So this means that it takes longer for the bread to go stale.

Previously, animal fat and fish oil were added to the dough to delay it from going stale. But in the modern baking process, palm oil is widely used instead. However, the growing of palm for oil production has negative environmental effects like loss of habitat for wildlife when forests are cleared to make way for palm plantations. Another alternative is to use vegetable oils(5).

Ultimately bread-making can be easy and fuss-free, if we take the time to understand the process and practice. I hope that I’ve dispelled some of the mysteries of bread-making that I hope will help you start making your own bread without fear.

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Until the next issue, take care!

~ Lina

The Rise of Bread Baking

History of bread

History of yeast and commercial yeast production

Chemistry of Bread-making

Can bread stay fresh longer?

Further Reading

The Rise of Bread Baking

History of bread

History of yeast and commercial yeast production

Chemistry of Bread-making

Can bread stay fresh longer?

Further Reading

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