What is yeast?
Yeast is a fungus. But not like porcini mushrooms or champignons. It is infinitely smaller and we can only see it when it "multiplies". When he "grows up", in short. Biology explains to us, in fact, that yeast is a unicellular microorganism.
In the kitchen, however, the term yeast has a broader meaning. In addition to the natural one, made up of living organisms such as brewer's yeast, the word "yeast" refers to everything that is capable of swelling the dough. In any case, the effect created inside the dough is that of the development of many air bubbles, which cause it to grow in volume. Depending on the type of yeast we are going to use, the result will be more or less the same, but the process that implements this growth will change.
The types of yeast
So what are the types of yeast?
Yeasts can be:
- Natural: brewer's yeast; sourdough or sourdough starter
- Chemicals: instant yeast; ammonia for desserts; sodium bicarbonate
Natural yeasts
What are natural yeasts
And here we must turn again to our dear biology. Yes, because natural yeasts are precisely what we defined a few lines ago as "mushrooms" and "microorganisms".
To explain it in more detail we should add that yeast is a living being that is able to grow if it is in the right environment: humid, warm and with the availability of "food". A bit like us human beings, except that instead of growing in an apartment, yeast fits perfectly into our dough.
Natural yeasts are very fond of sugars that we find, for example, in flours. The more our yeast gorges itself on these sugars, the more it produces waste substances that are very useful for us. In the presence of oxygen and aided by heat, the yeast releases carbon dioxide. If the yeast is inside a flour-based dough, the gluten contained in it will ensure that the gas emitted does not disperse. And this is how the magic of leavening works.
A spell, however, always has its tricks:
- If we are preparing bread, pizza, focaccia or a savory pie, it will be useful to add a pinch of sugar to help the dough rise better. Let's fatten up that yeast!
- Sifting the flour will help the dough incorporate more air
- Working for a long time or "beating" the dough will allow even more air to enter, making our bread or pizza even softer and more digestible.
Brewer's yeast
Brewer's yeast is the most used by man and for the longest time: just think that the ancient Egyptians already used it! For millennia it has been the creator of wonderful things such as bread, pizza, very soft cakes, but also wine and (look at that!) beer.
In fact, if this yeast, feeding on sugars, is in the presence of oxygen, it gives rise to leavening. However, if oxygen is lacking, then it produces ethyl alcohol.
Its advantages in baking are truly numerous: first of all it is economical; then it is also very simple to use; it is rich in vitamins and mineral salts and, compared to sourdough, it has faster leavening times.
It is also a very easy yeast to find: all supermarkets have a good supply of it whether you want it fresh or prefer it dry.
It is also a very easy yeast to find: all supermarkets have a good supply of it whether you want it fresh or prefer it dry.
Fresh brewer's yeast and dry brewer's yeast: what are the differences
On the market we can find brewer's yeast in two variants: fresh in cubes or dry powder. Dry yeast is really nothing strange or extraordinary: it's just dehydrated brewer's yeast and the difference in performance is next to nothing.
Conversion between fresh brewer's yeast and dry brewer's yeast
The ratio between fresh brewer's yeast and dry yeast is 3:1. This means that a 25g cube of fresh yeast corresponds to 7 of dry yeast.
How to store brewer's yeast
While dry yeast lasts much longer, fresh yeast lasts about a week if kept in the fridge and, once opened, it must be consumed within 3-4 days at most.
If we decide to freeze fresh brewer's yeast, we should be careful to close it well in transparent film or aluminum foil before placing it in the freezer. Once thawed, it should be consumed within 24 hours and used at room temperature.
How to use it: to activate or not to activate brewer's yeast?
Fresh brewer's yeast must always be activated in order to work well. Just dissolve the cube in a glass of water at room temperature before adding it to the dough and that's it: you will immediately see bubbles forming a dense and soft foam. That is exactly the signal you need: it means that your brewer's yeast is already active and ready to make the dough thicker.
If, however, you have opted for dry brewer's yeast, you can very well use it without activating it in the water and pour it immediately together with the flour.
How to make brewer's yeast at home
If you are a DIY lover, but also a tireless baker, you can try your hand at producing brewer's yeast. Where to start? Well, from beer! But I recommend that it is a craft beer and not filtered, otherwise you will never have the basic ingredient of this recipe: yeasts!
Get yourself:
- 100 ml of unfiltered craft beer
- 1 tablespoon of 0 flour
- 1 teaspoon of sugar
Usually the yeasts tend to settle at the bottom, so before using the beer you will have to shake it a little (but not too much, otherwise as soon as you uncork the bottle you will get a nice geyser effect!). And now comes the hard part…
No, come on, we were joking! It's really a very simple recipe: mix the beer, flour and sugar together in a container. As soon as you get a smooth and homogeneous batter, cover the container and leave everything to rest in a warm place for a day and... wow! Homemade brewer's yeast is done!
The sourdough starter
But how many names does sourdough have? Sourdough, sourdough, sourdough, sourdough and even growing dough. How confusing huh? But let's cut the bullet and see what this yeast is which we will always call here, for simplicity and peace of mind for everyone, sourdough.
First of all, sourdough is obtained by taking a piece of already leavened dough, which is set aside and left to "mature".
It is difficult to achieve a good result in its preparation and it really takes a lot of experience, but once you find the right way, the bread you prepare will gain points in flavour, aroma and will be enriched with many small substances that do us a lot of good.
For example, lactic ferments are present in mother yeast, which perform a probiotic function that eliminates bloated stomach problems that are generally created by leavened doughs.
Mother yeast really gives many advantages to our dough:
- Better digestibility
- Stronger taste and aroma
- Better shelf life
- Fragrance and softness
On the other hand, sourdough has longer leavening times than brewer's yeast and requires significantly more care and attention.
How to make sourdough at home and how to freshen it
As we told you, the advantages of sourdough are numerous, but for its preparation you will have to arm yourself with patience and take care of your master yeast (the little piece left to mature) a bit as if it were your child. After all, you are effectively growing a culture of many microorganisms, real living beings!
Ready? Well! If you want to make sourdough at home, first of all get:
- Two parts flour (50g and 50g): the flour already contains yeasts, which in this case will be "stimulated" and increased
- One part of water : 50 ml
- Half a teaspoon of sugar or honey or malt : it will be the so-called stater , or what will start the fermentation
These are the basic ingredients. During the next steps we will gradually add flour and water.
Let's now see what the steps are create the sourdough starter :
- Mix the ingredients together and knead until you obtain a soft mixture. Place it in a glass or ceramic container. The container must be tall and narrow. Score the dough by making a cross cut. Cover it with a damp cloth and let it rest for 48 hours at room temperature. Once the necessary time has passed, it should have doubled in volume.
- After the rest time, we will have to move on to the first refreshment. Refreshing the sourdough starter several times is essential to lower the acidity that has been created in the starter yeast and to make it return homogeneous and compact.
So here are the steps to refresh the sourdough starter .
- Take half the mixture and add two parts of flour (100 g) and one part of water (50 ml). Now mix the ingredients
- Throw away the half set aside
- Clean the container with only hot water and place the refreshed yeast in it, cutting a cross on it
- Let it rest for 48 hours
- Once the necessary time has passed, repeat the refreshment and wait another 48 hours
Did we tell you or not that making sourdough at home is almost like taking care of a child?
How to store sourdough starter
The sourdough starter can be stored either in the fridge or at room temperature, but in any case it is necessary to refresh it regularly: every 7-10 days if you leave it in the fridge or every 1-2 days.
How to use sourdough to make bread , pizza and cakes
Every time you want to use sourdough, you will have to carry out a series of refreshments close together within 24 hours, once or twice, if you need to prepare simpler products such as bread or pizza, or three times for more complex recipes. like panettone. Always allow 3-4 hours to pass between refreshments.
As regards the doses of yeast to be used, these change depending on the recipe:
- Bread : 200 g of sourdough for 1 kg of flour
- Pizza : 200 g of sourdough starter for 1 kg of flour
- Desserts : 350 g of sourdough starter for 1 kg of flour
Once the dough is ready, remember that the leavening in this case is really slow, so let the dough rest and don't dare bake it before at least 24 hours have passed! Really: it takes a lot, but the result is seriously worth it.
Dry sourdough: what it is and how to use it
For those who don't have time or simply have no desire to raise fresh sourdough, you can find an easier version in supermarkets: dry sourdough.
It is dehydrated mother yeast to which a pinch of another leavening agent is added, which acts as an "activator", such as brewer's or dry yeast. So be careful: it is not a pure version, but rather a compromise that simplifies the use of sourdough and reduces its time.
Ok, but how do you use this wonder? First you need to reactivate it, so pour it into a glass of warm water and mix well. Leave it to rest for a couple of minutes and then add it to the dough.
How long should you let the dough rest? But very little compared to fresh sourdough! 5 or 6 hours maximum will be enough, nice, right?
Chemical yeasts
Don't be fooled by appearances: the word "chemical" in this case has absolutely nothing negative. The process to obtain them is, yes, a chemical process and the leavening it triggers is also a chemical leavening. But don't associate the term "chemical" with something negative: chemical yeasts are absolutely not harmful to our health, in fact, they are often a valid help!
You know when you feel weighed down and need something to help you digest quickly? You will probably take some baking soda and dissolve it in a nice large glass of water. Well, bicarbonate is part of the chemical yeast family and in addition to being a healthy touch for digestion, it is also very useful in the kitchen. These chemical yeasts are not bad, right?
What are chemical yeasts
Chemical yeasts are substances which, thanks to heat and the development of steam, trigger a chemical reaction, through which carbon dioxide is released. This creates bubbles inside the dough making it grow and making it very soft. By virtue of their activation by the heat of the oven, these yeasts are very simple to use and the dough does not need many hours of rest. Pour them into the dough together with the dry ingredients and off you go in the oven!
It can definitely be said that these yeasts are truly synonymous with practicality and efficiency!
Yet, as we know, nothing is perfect and even chemical yeasts have a small flaw: if used in excessive quantities they can release a vaguely bitter taste. But don't worry! There is a remedy for everything and in this case it is really simple to find it! In fact, usually the unpleasant smell goes away on its own as soon as the preparation cools, but if it really has been exaggerated too much, there are still some easy precautions to take advantage of.
If you are preparing a dessert with a chemical yeast, just add a little lemon juice or a little vanillin, or, in the case of bicarbonate of soda, you can also opt for the combination with cream of tartar.
Chemical baking powders are usually already vanilla-flavoured and, by purchasing a quality product, there is really no risk that the vanilla supply is poorly calibrated.
So here we are back to square one again: practicality and efficiency, people!
Instant yeast dry or chemical yeast
It is the most widely used baking yeast both at home and on a professional level. It is so common that it is referred to par excellence as "chemical yeast". Fast, "instant" and with high performance, the dream team that composes it is made up of: corn starch (or potato starch), sodium bicarbonate and an acid substance. Together they make up a compound that makes leavening stable, which, as we will see, is less easy to achieve with bicarbonate alone.
In the non-vanilla versions we also find instant pizza yeast, which can also be used in focaccias and savory pies. The great advantage here also lies in its speed of use: just pour it into the dough together with the dry ingredients and bake everything. As; right away; without waiting for any resting time for the dough. Now that's a pizza express!
Sodium bicarbonate like yeast
It is the oldest among chemical yeasts and is widely used by Anglo-Saxons and Americans. Sodium bicarbonate also boasts a rapid leavening effect. Compared to dry yeast, however, you need to pay attention to two things in particular:
- Baking soda tends to work very quickly and wear off its effect just as quickly. You must therefore hurry up and put it in the oven if you don't want to see your cake first rise in the oven, but then sadly sink again.
- Baking soda should never be used alone. In fact, if combined with an acid, bicarbonate acts with greater strength: the bubbles in your dough will be many more! It is usually used together with lemon, cream of tartar and sometimes vinegar.
Ammonia for desserts: what is it?
Let's start by clarifying one thing: ammonia for cakes has nothing to do with the ammonia used to clean the house. Well, if someone had the unhealthy idea of replacing this yeast with ammonia for cleaning, well: stop it!
But then why does it have this name if it is not ammonia? The mystery is easily revealed: just quickly see how this leavening works.
Ammonia for desserts is nothing more than ammonium bicarbonate and during cooking it decomposes into three substances: carbon dioxide, steam and ammonia. The latter, however, is an extremely volatile element, so it goes away once cooked; disappears; it evaporates into thin air so quickly that we don't even notice.
Ammonia for desserts: what is it used for?
Generally, baking ammonia is used for the preparation of dry pastries, such as biscuits. It is in these cases, in fact, that this yeast gives its best, making our preparations unparalleled in crunchiness and friability.