Currently, some things are hard to come by in the supermarket as people still seem to be panic buying. The Corona crisis taught us that toilet paper is the new cash, but even flour and yeast are difficult to get – this might be because many of us have more time for baking (yes, including me!). And in times like these, baking is a great way to introduce some nice flavors and good mood into everyone’s home – but how to without the necessary ingredients?

I have not found a reliable source of flour yet, but I found quick and easy ways to multiply yeast or even make it from scratch that I wanted to share today:
How to multiply yeast
To start with, you need a few simple ingredients:
- 100 g of flour
- 15 g of sugar
- 100 mL of water
- 1 bag of dried yeast or half a cube of fresh yeast (or less, whatever you might have)
Of course, you can start with less yeast if you don’t have as much. You can always modify the recipe, just keep the ratio of roughly 1 flour : 1 water : 0.15 sugar.
Before you mix all ingredients, make sure that you are working in a clean environment with clean dishes: You don’t want to multiply all other kind of bacteria. Mix the ingredients and give them time to multiply in a warm and dry environment. Make sure to use a big dish so the mix can enlarge and cover it with a foil or cloth to keep it clean.
Give the bacteria sufficient time to multiply: If you don’t, you will not increase the amount but just stretch the yeast over some dough. Let it rest overnight for about 12 hours at room temperature.
Afterwards you can just use it fresh, store it in the fridge for a few days or even freeze it. Be aware that freezing deteriorates the bacterial structure quickly, so you can only store it in the freezer for a few weeks.

The performance of your resulting yeast will vary, as it is a natural product. I have been using my latest batch in the same amount as conventional yeast and it worked just great. If yours is not as active, you might have to wait longer e.g. before baking. That is always a way to reduce your use of yeast, just use more patience!
How to make yeast from scratch
If you don’t have any yeast to start with, you can also make your own from scratch and without flour! It takes several days to finish, but is still very easy to do. You need a clean and high glass container like a Mason jar that you might recycle from a milk bottle or canned vegetables. To make sure it is free of other bacteria, you can rinse it with boiling water in the sink after cleaning.

Start the fermentation with:
- 50 g of raisins (Best use organic ones! )
- 1 tbsp sugar
- 500 mL water
Instead of raisins, you can also use other kinds of dried fruits such as apricots or figs. Pour the raisins and sugar in your glass and soak it with warm water. Close the lid and shake it until the sugar is solved. Loosen the lid of the glass because there will be gas that needs to get out to avoid a messy explosion! Make sure the lid keeps dust from getting into the bottle while it is open enough to let gas out. Keep this mix at a warm location (around 30 °C would be best) for 3-8 days. Make sure to shake it quickly and lift the lid about twice a day.
Your yeast is finished once the fruits are swimming on top of the water, it smells like yeast and there are no more bubbles forming. You can then sieve the fruit, close the lid and store the mix in the fridge for several months – or use it right away.
To use it, you can replace half a bag of dried yeast (4 g) or 12 g of fresh with about 150 mL of the yeast water, that is enough for 500 g of flour. Make sure to eliminate the same amount of any other liquid from your recipe (e.g. water or milk) to achieve the correct viscosity of your dough!
Making or multiplying your own yeast will help you be more self-sufficient, it can help to avoid plastic waste and unnecessary (or unsuccessful in times of Corona) shopping trips. What other zero waste or home-growing tips have you recently learned?