By Sebastian Sturm.
Bread isn’t just bread. Bread is much more! Bread is one of the most important foods of humankind. Bread is culture. Bread is an essential part of human history and a driver of division of labour in early human societies. For the starving, it is the difference between life and death. For others, it is a way to maintain their power over commoners: “Bread and circuses (games)” is an old concept to control the masses.
But bread is also an interesting topic from a scientific point of view. Today’s NICE – Lab blog is dedicated to pointing out some bread-related aspects in history, botany and chemistry and of course a baking recipe for you to try at home. Here we go:
The oldest evidence of humans baking bread comes from some Upper Palaeolithic excavation sites in Europe (about 30.000 ya). Grinding tools found in Italy, the Czech Republic and Russia contained residuals from cattail and ferns1.
The big breakthrough of baking goes hand in hand with humans starting to cultivate grains. The beginning of agriculture began about 10,000 years ago in the Neolithic age. The establishment of agriculture enormously changed the social structures of human communities and facilitated a rapid technological development due to the steady supply of food.
The first crops being domesticated were the einkorn wheat (Triticum monococcum) and the emmer (Triticum dicoccoides) in the Near-Eastern Fertile Crescent (from the Sinai Peninsula over Syria to the Arabian Gulf).
Triticum – wheat – is a genus from the family of grasses (Poaceae). Today, wheat provides 20% of the world’s consumed calories and protein2. Wheat belongs to the first organisms to which genetics were applied – 10,000 years ago. The wild wheat’s ears easily fall apart and release the grain – a very unfortunate trait (brittle rachis) since you lose the yield during the harvest. Mutations of the brittle rachis genes disabled the grain ejection mechanism to the disadvantage of the plant but to the benefit of humans, enabling an efficient harvest3.
The modern bread wheat (T. aestivum) is a hexaploid plant – it possesses six sets of its chromosomes. Bread wheat is the result of hybridization of domesticated emmer which has four sets of chromosomes with Tausch’s goatgrass (Aegilops tauschii) which is only diploid3,4 (just like humans).
The recipe presented in this blog – onion bread – features many interesting chemical reactions. The bread itself is a biochemical reactor. Once the water is added to the flour, enzymes from the wheat grain are activated. The enzyme α-amylase starts to cleave the starch – long-chained sugar molecules – into smaller units and its relative, β-amylase further cleaves them into sugar monomers.
The yeast consumes the produced sugar and it can swap its mode of operation. In the beginning, oxygen is available to the yeast and it can “breathe” the sugar, producing water and carbon dioxide as by-products. Note from the editorial office: I want you to calm down. Yeast does not contribute to man-made climate change. It contributes to yeast-made climate change. Once the oxygen is consumed, the yeast will start to ferment the sugar to carbon dioxide and ethanol. This phase is essential for the flavor of bread. For this reason, the dough has to mature and leaven for a while without kneading.
Another interesting process that occurs during baking and preparing crispy fried onions is the browning. Browning adds flavor and color to the food and mainly relies on two chemical processes: Caramelization and the Maillard reaction. Caramelization of sugars occurs at temperatures between 110-180°C and comprises numerous chemical reactions. The Maillard reaction is the reaction between sugars and amino acids at temperatures around 150°C resulting in versatile flavorous products.
Onion bread (for 2 small / 1 big loaf)
- 500 g lukewarm water or vegetable stock/broth (for extra flavor)
- 3 tbsp. dry yeast
- 3 tsp. sugar
- 3 tsp. salt
- 1 kg wheat flour
- 400 g crispy fried onions
Take a bowl, add 50 ml of warm water and mix it with the yeast. Wait about five minutes, add the sugar and stir it till the sugar dissolves. Put the flour on the countertop or into a big bowl and shape it into a volcano. Check your yeast – if it’s a fragrant puddle of liquid topped with a fancy pile of foam it’s a happy yeast and ready for our bread. Now, throw the salt in the throat of the flour volcano and extinguish it with the remaining water or broth. Gently push some flour into the middle of the volcano, mix it and repeat until the flour has bound to all the liquid. Then start to knead the dough until it’s smooth. Then cover the dough with a clean towel and let it rise. Meanwhile prepare the crispy fried onions, write a blog or do whatever you are supposed to do when you have 45 minutes to yourself. After 45 minutes, the loaf should have risen and doubled in volume. Now preheat your oven to 200°C. Take your crispy fried onions and gently massage them into the dough. Depending of the size of your oven shape appropriate loaves or buns. If there are crispy onion pieces on the surface, poke them inside and cover the hole with the dough. Bake the shaped bread loafs at 200°C for about 40 minutes till they look nice and yummy.
Tip: Give the unbaked bread an egg wash: brushing the dough with an egg mixed with a spoonful of water – the Maillard reaction occurring during baking will add a nice golden-brown tan and extra flavor.
For the crispy fried onions
- A saucepan with plenty of oil (e.g. sunflower seed oil)
- Flour (a few spoons full)
- A plastic bag, a strainer and some paper towels
Heat the saucepan with a sufficient amount of oil – the onion rings have to swim in it. Meanwhile cut the onions in rings. Take two handful of onions, put them in the plastic bag and add two tablespoons of flour. Gently shake the bag to coat the onions with flour. To test if the oil is hot enough, sacrifice a test-onion. If it floats and is surrounded by bubbles it is good to go (Warning: Residual water might splatter hot oil!). Take a ladle and transfer the powdered onion into the hot oil. Gently stir the onions from time to time. When they are golden brown, strain the onions and place them on the paper towel to remove residual oil. Repeat for the next batch of onions. Don’t use too many onions in one go since they will drop the temperature of the oil. You can reuse the strained oil. If you have a salad spinner – give it a shot to remove the residual oil!
Baking onion bread is quite some work. “Bakery isn’t only a job – it is a profession!” That’s what my relatives told me who were members of the high guild of bakery. Indeed, this job requires enthusiasm since you must get up very early in the morning to have the pastries ready when other people want to buy fresh rolls and bread for breakfast. Today, the art of baking bread is endangered by rapidly growing franchises whose automated production can outcompete local bakeries. I think that my first self-made onion bread was very tasty. Remembering the unique smell and flavor of the ones my grandfather used to make, I know what mine is missing: decades of experience.
1. Revedin et al. 2010 https://doi.org/10.1073/pnas.1006993107
2. Jones et al. 2017 The wheat and nutrition series, CIMMYT
3. Avni et al. 2017 https://doi.org/10.1126/science.aan0032
4. McFadden & Sears 1946 https://doi.org/10.1093/oxfordjournals.jhered.a105590