The Science of Sourdough

The science of sourdough is both simple and complex. The simplicity lies in the small list of ingredients contained in a loaf of sourdough bread – just flour, preferably organic wholemeal, water, salt and time. The complexity lies in the magic that happens when you mix these four ingredients and let them do their thing!

The green revolution of the post-WWII era changed bread from a wholesome product that had supported the growth of civilisation to a pawn in the game of food politics. Industrial agriculture produces a loaf far removed from the staff of life, a nutritional pariah now avoided by many in the 21stcentury. So while modern manufacturing has made bread cheaper, why is it that many people can’t digest it and what’s the difference between the two?

At Bread and Butter Bakery we only use organic stoneground flour, as it’s full of nutrients, minerals and fibre, which help to keep your gut healthy. Using organic ingredients means you’re not getting any harmful petrochemicals, pesticide residue or processing aids and you’re also supporting sustainable farming. And voting with your wallet is a simple but effective way of bringing about change on both a large and a small scale.

Organic sourdough bread has benefits that are threefold and affect the world on both a huge and a tiny scale. Firstly, the grains used are farmed in a sustainable way that doesn’t harm the planet or add to the factors bringing about climate change – in contrast, organic and regenerative farming methods build up soil carbon, thus mitigating the effects of industrial farming.  Secondly, those same organic ingredients are free from the harmful residue of agricultural chemicals that can build up in your body and affect your health – did you know that in New Zealand alone there are some 450 pesticides available for spraying on our grains and vegetables? This is in a country that doesn’t even grow a lot of grains! 

Wholemeal organic rye starter. At Bread & Butter Bakery we make ours quite firm, but other bakers might make theirs more runny. There is no rule that says a starter has to be a certain way.

Wholemeal organic grains carry naturally-occurring bacteria and wild yeasts on their husk. When mixed with water and allowed to sit at room temperature, the bacteria and yeasts get to work on the flour, releasing carbon dioxide as they go. This is the fermentation process. Gas bubbles up, making the dough rise, and at the same time, various acids are produced that help break down hard-to-digest parts of the flour. The acids add the distinctive sourdough flavour that we love and also improve its keeping ability. That’s why a loaf of sourdough will keep for days in your breadbin – if you can resist eating it!

One of the most important ingredients in sourdough bread is time. This is slow food at its best, a perfect antidote to the busy-ness of the modern world. Depending on temperature, water content, humidity and the flour type used it takes between 18 and 48 hours for dough to ferment, and it’s not a process that can be rushed. 

Sourdough bread doesn’t need conveyor belts, artificial flavours, dough conditioners, stabilisers, emulsifiers, colours, preservatives or quick-rise yeast – these are reserved for the modern, commercial loaf, the fluffy white stuff that many people think of as bread. Soft, white commercially-produced bread is the result of the Chorleywood method – developed in 1961 and now used around the world (see “A slice of Life” Post from last week

Bread made by the Chorleywood method uses a premix of ingredients that come from industrial farming, containing residues from lots of chemicals. Premix is complicated. It can contain dairy products, sugar, modified fats, artificial flavours, colours, preservatives, emulsifiers and dough conditioners. The flour used is white, low in fibre and very short on vitamins and minerals. While these are stripped at the time of milling, artificial vitamins and minerals are added back in later, in a process known as ‘fortifying’, implying that the bread is good for you.

Where sourdough takes time, commercial bread uses technology – fast-acting yeast and vigorous mixing produce a loaf of bread in under four hours– from a bag of premix to a bag of sliced bread, ready for the supermarket shelf. There’s no time for natural flavours to develop, and difficult to digest components, such as gluten, stay in their ‘raw’ form, which could be contributing to the high numbers of people who find they now can’t tolerate white processed bread.

Thirdly, sourdough is really good for the community of bacteria living in your gut, which are now acknowledged as essential for wellbeing.

As a baker and a scientist, it pains me to see bread getting a bad name and to hear people saying “I don’t really eat bread, it’s bad for you.” I have to remind myself that most people are thinking of supermarket squishy white fluff when they say bread while I am thinking of crusty rye sourdough loaves. I think they have a point when they say “I don’t want to eat this fluff any more”. I think it’s a step in the right direction. 

Rye & Walnut Sourdough and house made butter.

That fluffy white stuff was never real bread anyway. Real bread is wonderful, so satisfying even with just some butter, but also versatile. You can put almost anything on bread, savoury or sweet, and old bread can be dried and ground into bread crumbs, used in sweet and savoury bread-and-butter-puddings, French Toast and more. See below for some of my favourite recipes that have bread as the star ingredient.

And here are some things you can do with bread:

Rye Sourdough Toast with smashed avocado, vine tomato & percorino

Wholemeal rye bread has one of the highest fibre contents of any foods out there and one slice as an open style sandwich will keep you going from lunch until dinner without any cravings of sugar in the afternoon. Per person you need:

1 slice of wholemeal rye sourdough, i.e. Bergsteiger or 100% Rye from Bread & Butter Bakery

half a ripe avocado

1 ripe vine tomato

shaved or thinly sliced pecorino or parmesan cheese

Pepper to taste

Spelt Toast with Crunchy Peanut Butter and Banana

This is a favourite afternoon snack for young and old. Easy to prepare and full of good nutrients (good fats and protein from peanut butter, minerals and fibre from the bread, and potassium from bananas). Per person you need:

1 slice of Spelt bread, i.e. Swiss Loaf from Bread & Butter Bakery

1 table spoon of crunchy (or smooth) peanut butter of your choice (Fix & Fogg do an amazing chocolate version, but my favourite is probably Pics crunchy peanut butter)

half a banana

Cinnamon for sprinkling on top

Bread Crumb Crunchy Biscuits

This recipe is great to use up old bread. I always throw ends of bread into a paper bag, which I keep in my hot water cabinet. They dry out nicely and don’t go mouldy. When I need bread crumbs of any kind, I just blitz them up in the food processor. It’s fine to use a mixture of different breads here.

125g / 1 cup bread crumbs toasted to light brown

125g/ 1 cup flour (can be spelt or wholemeal)

125g / 1 cup desiccated coconut

65g/ 1/2 cup golden or brown sugar

100g melted butter

1/4 teaspoon salt

1 table spoon golden syrup or other syrup (i.e. rice, date or agave)

Mix all the ingredients together. Add a little milk or coconut milk, if the mixture is too dry. Roll into log and cut slices, or drop spoons full on a baking sheet lined with baking paper. Bake at 160C fan bake or 170C for approximately 20 – 25min or until golden brown.

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