Yeast

Yeast

What are yeasts?

They are single-celled microorganisms that belong to the kingdom of mushrooms.

There are various kinds of yeasts and the species used in the world of baking is that of Saccharomyces Cerevisiae, more commonly called saccharomyces. These are small living organisms (5/10 micrometers large) which despite their size are fundamental in leavening processes.

Saccharomycetes feed on sugary elements, complex and simple, creating through this process carbon dioxide and ethyl alcohol.

Leavening products are varied and we can divide them into three categories:

– Sourdough;
– Brewer’s yeast (fresh and dry);
– Instant (chemical) yeast powder;

Mother Yeast

Mother yeast, also called natural yeast, is not a pre-dough, it is not part of the same “family” of biga and poolish.

It is a mixture of water and flour subjected to spontaneous contamination by microorganisms present in the raw materials, in the air, and in the environment in which it is created.

It is a living product and as such it must be nourished, it requires a lot of care, and to make it correctly you need to have good knowledge of the transformations that take place within it.

This mass is erroneously called “yeast” as the main elements responsible for its fermentation are not saccharomyces but lactic bacteria.

Beer’s Yeast

It is so called because, historically, it was extracted from the deposits that formed during the fermentation of beer musts, and on the market, we find it both fresh and dry.

Fresh brewer’s yeast is composed of 70-75% water and 25-30% of the active substance (saccharomycetes), is commercially available in the form of loaves and can be stored in the refrigerator at 4 ° C for a maximum of 15 days.

In the second variant (dry brewer’s yeast) the percentage of water is lacking giving life to a dehydrated powder product: this facilitates its conservation allowing it to be preserved outside the refrigerator. As you can imagine, eliminating the part of water will result in a more concentrated element, and on the market, it is available in bags of various sizes.

Instant Yeast Powder

This type of product is made up of chemical substances which, with the action of heat, release gas, allowing it to rise; the most commonly used is baking soda.

Understanding the differences between the various leavening products is essential to choose the right one in our field.

In the production of pizza dough, the most suitable are sourdough and brewer’s yeast because they allow the fermentation, leavening, and maturation processes.

Chemical yeast is not indicated as it is a product that is triggered directly during cooking, not allowing the dough to undergo the three fundamental processes that occur thanks to microorganisms.

When using yeast it is essential to know two factors that influence our doughs and we can divide them into two categories: life and quantity.

The life

Yeast, like us, is born, grows and dies. Its path is marked by temperatures and conservation methods.

In this study, we must divide the types of yeast to understand how to keep them.

Dried sourdough and dry brewer’s yeast can be stored at room temperature, in the classic kitchen shelving, possibly far from heat sources; these two types, being dehydrated, have a longer life and we don’t have to worry about the expiration date.

The sourdough (if created by us) and fresh brewer’s yeast should be kept in the refrigerator and the suitable temperature is 4 ° C; being fresh products with high percentages of water, keeping them in places with uncontrolled gradations for a long time would shorten their life, making them unsuitable for leavening processes. These two products can be frozen: at a temperature below or equal to 0 ° C we will stop their life.

Now it is essential to understand how the temperatures to which we subject our doughs affect the yeast.

At a temperature between 4 °C and 6 °C our leavening will take place slowly, the development processes that we will have in our doughs will be long; this is the classic refrigerator temperature, for maturation of at least 24 hours.

From 6 °C to 15 °C our product will develop faster but not at full capacity.

Between 15 °C and 35 °C the yeast will constantly accelerate the development of our doughs; this range includes the classic ambient temperatures.

Temperatures between 35 °C and 55 °C are particular conditions, in which we hardly find ourselves, however the yeast still proceeds in its function.

The temperature path makes you understand how to make your dough rise and mature: the lower the temperature, the more time we will have at our disposal; on the contrary, if we let the dough rise at room temperature, the process will become faster.

The timing must be dictated by the choice of flour (it all depends on you): if we choose a weak flour we can opt for a dough that rises at full capacity and therefore in a few hours, which is not recommended to do with medium or strong flour.

Quantity

The recommended amount of yeast to use in our dough varies according to the type of product we are going to use:

Sourdough 50 grams per kilo of flour;

Fresh brewer’s yeast 3 grams per kilo of flour;

Dry yeast 2 grams per kilo of flour.

The difference in quantity is due to the leavening capacity of these products.

Sourdough is a natural culture of microorganisms that has lactic bacteria as its main causes of fermentation, which unlike saccharomycetes produce lactic acid, acetic acid, water, carbon dioxide, and secondary metabolites; the quantity varies so much from the other types as it has less leavening power.

Fresh brewer’s yeast should be used in small doses to trigger the fermentation processes since within it we will find only one category of microorganisms (saccharomycetes), capable of carrying out a more targeted action.

Dry brewer’s yeast needs to be used in smaller quantities, its fermentation power is accentuated by dehydration, which concentrates the presence of yeasts in a smaller quantity of product.

The yeast should be used in small quantities unless it is sourdough, otherwise, we will have products that will rise too quickly, the internal processes will happen too quickly and our final dough will be incorrect.

The amount of yeast to be used does not vary according to our needs or products. If we want to make a quick dough we do not increase the quantity of yeast but, on the contrary, we use a weak flour suitable for short leavening; if we choose a medium or strong flour we must leave the proper maturation time for our products to have a correct result (here the article on flours).

In conclusion, giving the fundamental notion for the use of yeast: in the creation of our doughs, it must NEVER come into direct contact with salt. This information is very important because salt contrasts yeast compromising its action.