Yeast is one of the ingredients that have defined the history of gastronomy and cooking. We discover what it is, its historical importance, and its multiple culinary uses.
Yeast is an essential element for all types of baked goods. There are various substances behind this name, although, in reality, the true yeast is a fungus. That’s right, it is a unicellular fungus used in the fermentation of food and drinks, not only in bread and pastries, from which we take advantage of its ability to transform sugars into alcohol and carbon dioxide.
What is yeast and what is it used for?
Yeast is a type of unicellular fungus that belongs to the Fungi kingdom (or kingdom of fungi). This is important because it is not a bacterium, but a much more advanced, versatile, and resistant microorganism. There are many different species of yeast, but the most well-known and used by humans is Saccharomyces cerevisiae or brewer’s yeast. Be careful! Real yeast should not be confused with the wrongly named “chemical yeast”, which is a product that produces CO2 through a chemical decomposition reaction, without the involvement of any living being or sugar.
Back to Saccharomyces, basically, this organism is able to convert sugars into carbon dioxide and alcohol through a process called fermentation. This occurs in the absence of oxygen and results in alcohol and carbon dioxide. For this reason, yeast is the main reason we have alcoholic beverages, since under the right conditions, water and sugar are enough to ferment a liquor from which we can distill or make a drink such as beer or wine.
However, in cooking, yeast is mainly used for making bread, cakes, and other baked goods. Carbon dioxide, which was the other substance from the reaction, makes the dough rise, while the alcohol evaporates during baking.
Yeast can also provide certain nuances and flavours to both baked goods and alcoholic beverages because they are complex living beings and not mere machines for producing CO2 and alcohol. For this reason, and because of the conditions in which they can work, yeast varieties are so important for each particular case in the industry.
In addition to its application in the food industry, and although we will not discuss it here, yeast is also used in biotechnology and medicine, for example, in the production of insulin and other medicines, forming important bioreactors. As if all this were not enough, it can be used as a food base, due to its richness in nutrients, or within the world of research, among many other uses.
Origin and history of yeast
In reality, yeast as an organism is many millions of years old, although it is true that studies have shown that the variety of strains that we have available today for use in cooking have evolved from a few ancestors and diverge significantly from wild yeasts, which is a clear example of domestication.
The history of yeast in human cooking dates back thousands of years. Perhaps the oldest archaeological evidence of the consumption of fermented cereal dates back to the Natufian culture, that is, more than 9,500 years ago (much earlier than the Egyptians, by the way). According to some experts, and who knows if this was true, “we can speculate that the magical evolution of sugary musts into an intoxicating and everlasting brew occurred empirically in fruit or grain stores,” which, by luck or tenacity, ended up bringing the results of these tests to the tables of our ancestors. During all this time, as we can imagine, human beings have been selecting those strains that most interested us for their results, through trial and error.
We know that the Egyptians were among the first to use wild yeast to raise bread and that this knowledge was passed on to the Greeks and Romans, who also used yeast in the production of bread and alcoholic beverages, although without a full understanding of the biological processes involved. During the Middle Ages, yeast took on a crucial role thanks to monasteries, which became centres of beer and bread production. However, it was not until the 19th century that the French scientist Louis Pasteur discovered that fermentation was a biological process carried out by living microorganisms, identifying yeast as the agent behind this process. This discovery marked a turning point, allowing for much more precise control of fermentation processes.
With the advent of systematic industry, the production and use of yeast in food expanded exponentially, with methods being developed for large-scale production. In recent times, thanks to advances in genetics and molecular biology in the 20th century, yeast has reached new heights as a protagonist, as these organisms have allowed us to achieve a deeper understanding of biology in general and of yeast in particular, facilitating genetic manipulations to optimize its use.
Today, yeast is not only central to the food industry but also has applications in biotechnology, from biofuel production to medicine. In addition, there is a growing interest in sustainable and natural practices, which has led to a resurgence of traditional fermentation techniques. Yeast, with its long history and wide range of applications, continues to be an essential microorganism in our society, with potential yet to be explored.
Types of yeast
There are many ways to classify yeasts: by species, by variety, by uses… We are mainly interested in their application in cooking, clearly, so we can identify yeast in the following way.
These are the most common types of yeast, but there are many other varieties and strains of yeast used in the food industry and in biotechnology. Each type of yeast has unique properties that make it suitable for different applications.
Fresh Yeast (or baker’s yeast)
Fresh yeast, also known as pressed or baker’s yeast, is a moist form of yeast sold in blocks or cubes, alive. For this reason, it is very active and requires refrigeration so that it does not die and dry quickly. It must be dissolved in water before use and is ideal for baking.
- Advantages: Provides a rich and authentic flavour and aroma to bread. Excellent for doughs that require a long fermentation time.
- Disadvantages: It has a short shelf life and must be kept refrigerated. It may be harder to find in stores.
- Purpose: Artisanal breads, doughs with long fermentation times.
Active dry yeast
Active dry yeast is fresh yeast that has been dehydrated, so it is not actually alive, but is in a state of cryptobiosis, or, in other words, “dormant.” It is sold in the form of granules and must be rehydrated in warm water, waiting a while, before use. It has a long shelf life and is widely used in homemade bread recipes.
- Advantages: It has a long shelf life and does not require refrigeration. It is more affordable and easier to find in stores.
- Disadvantages: Requires dissolving in water before use and may take longer to activate.
- Purpose: Homemade breads, traditional bakery recipes.
Instant dry yeast
Instant dry yeast is similar to active dry yeast but is processed differently, resulting in finer granules. It does not require rehydration before use and can be mixed directly into dry ingredients. Overall, it is faster and more efficient than active dry yeast.
- Advantages: Activates quickly, reducing fermentation time. Very consistent and easy to use.
- Disadvantages: Some bakers believe it offers a less complex flavor compared to fresh yeast.
- Purpose: Quick breads, when you have little time, commercial bakery.
Nutritional yeast
Nutritional yeast is a type of yeast that has been deactivated (yeast cells have been destroyed), so it has no fermentative capacity. It is used as a dietary supplement for its high protein, B-complex vitamin and mineral content. It has an umami (savory or fatty) taste and is used as a condiment in vegetarian and vegan diets.
- Advantages: It is a rich source of protein, B vitamins, and minerals. It does not contain gluten or animal products, making it suitable for vegans. It provides a cheesy or nutty flavour, enriching culinary preparations.
- Disadvantages: Although it is rich in nutrients, it should not be the only source of vitamins and minerals in the diet. Some people may be allergic or sensitive to nutritional yeast.
- Purpose: Food supplement, salad dressing, making vegan sauces and cheeses, adding an umami flavor to different dishes.
Brewer’s yeast
Brewer’s yeast is a by-product of beer production and is also sold as a dietary supplement, since, like nutritional yeast, it is rich in proteins, B vitamins, and minerals, but unlike the former, it has a more bitter taste.
- Benefits: Rich in protein, fiber, B vitamins, and minerals such as chromium, which helps maintain normal blood glucose levels. It can contribute to improving the health of skin, hair, and nails.
- Disadvantages: It may have a bitter taste that is not to everyone’s taste. Some people may experience gas or bloating when consuming it. It is not recommended for people with certain medical conditions, such as fungal infections or yeast intolerance.
- Purpose: Nutritional supplement, adding a nutritious touch to smoothies and other dishes.
Nutritional values of yeast
Yeast, particularly nutritional yeast and brewer’s yeast, is known for its high nutritional content and is often used as a dietary supplement. Its nutritional value can vary greatly depending on quality, type, density, condition, and many other factors. To give some average numbers as a guide, here are the figures for 100 g of yeast:
- Energy value: 343 Kcal
- Fats: 4 g
- Saturated Fats: 0.7 g
- Carbohydrates: 36.9 g
- Proteins: 51 g
- Sugars: 12.4 g
- Fiber: 22 g
- Salt: 0.18 g
- Calcium: 95 mg
- Iron: 5 mg
Properties and benefits of yeast
There are many beneficial properties of yeast. Here we review some of them, taking into account that the potential of these microorganisms for health is multiple.
It is important to note that although yeast is a powerful nutritional supplement, it should be consumed in moderation and not as a substitute for a balanced and varied diet. In addition, some people may be allergic to yeast or have a sensitivity to it, so it is important to be careful when consuming it.
Rich in protein
Yeast is an excellent source of protein, offering all the essential amino acids the body needs. This means it can help build and repair tissue, and is an important source of protein for vegetarians and vegans.
It is an interesting source of B vitamins.
Contains high amounts of several B vitamins, including B1, B2, B3, B5, B6, B8 and B9. These vitamins are essential for converting food into energy, maintaining healthy skin, eyes, and hair, and helping the nervous system function.
It is high in fiber content
Although not the best, yeast is a good source of fiber, so it contributes to digestive health, helps prevent constipation, and can play a role in regulating blood sugar levels.
It has a low-fat content
Despite its high nutritional content, there is one thing it lacks: fat. Indeed, yeast is very low in fat, and the fats it contains are mostly unsaturated, which gives it a very interesting profile.
Contains essential minerals in quantity
Yeast is a good source of minerals such as iron and calcium, as well as various trace elements and other substances. This helps in numerous physiological functions of health.
Antioxidant properties
Some evidence suggests that yeasts contain antioxidants (or antioxidant-promoting substances such as glutathione). These substances protect cells from damage caused by free radicals. Their effect is limited but still interesting.
It can help improve mood
Some studies suggest that B vitamins may have a positive impact on mood, helping to reduce symptoms of depression and anxiety. However, there is no specific effect or treatment.
Contraindications of yeast
Despite its numerous health benefits, in certain situations, it can have contraindications and cause side effects in some people. This is not common, although its adversities can cause some significant discomfort.
Allergies
Some people may be allergic to yeast and experience adverse reactions when consuming it, such as rashes, itching, swelling, and in severe cases, anaphylaxis.
Yeast intolerance
There are people who have an intolerance to yeast and cannot digest it properly, which can lead to symptoms such as bloating, gas, diarrhea, and upset stomach.
Autoimmune diseases
People with autoimmune diseases may see their symptoms exacerbated after consuming yeast, increasing inflammation and other symptoms related to the disease.
Drug interactions
This is quite rare, but yeast can occasionally interact with some medications, altering their effectiveness. It is important to consult a doctor before consuming it if you are taking medication, especially certain types of antidepressants and diabetes medications.
Excess purines
Yeast contains purines (like all living things), which the body converts into uric acid. Too much uric acid can lead to the formation of crystals in the joints, causing gout in people with metabolic problems.
How to use yeast: recipes and uses in cooking
Baker’s yeast is the star of the kitchen, transforming dough and adding volume to almost every baking recipe you can imagine. From homemade rolls to gluten-free bread, yeast provides the sponginess and airiness that distinguishes a good loaf of bread from a mediocre lump. How do you use each one?
- Fresh yeast should be dissolved in a warm liquid (such as water or milk) before mixing it with the other ingredients. The temperature of the liquid should be about 38-43°C (100-110°F) to activate the yeast without killing it. It is best to have it between the solvent and the dough for at least 20 minutes before cooking.
- Active dry yeast needs to be rehydrated in a warm liquid before use, similar to fresh yeast, although it doesn’t need as much time. In fact, once dissolved and activated (it will start to foam), it can be mixed with the other ingredients.
- Instant yeast can be mixed directly into dry ingredients without the need to rehydrate it first. It activates quickly and has a shorter fermentation time compared to active dry yeast.
Once you have chosen the yeast that best suits your needs, it is time to make delicious recipes such as homemade pizza dough or buckwheat bread, or, why not, some well-prepared regañás.
In the realm of desserts and sweets, yeast plays a starring role in the preparation of homemade brioche and milk buns, transforming basic ingredients into sublime, fluffy creations. The number of recipes using yeast is, we won’t say infinite, but it is incredibly prolific. Only the imagination sets the limits with this ingredient.
What is the best yeast for making bread?
Choosing the most suitable yeast for bread making depends on several factors, such as time available, baking experience, and the type of bread you want to make. In short, for making bread at home, active dry yeast and instant yeast are very practical and affordable options. For those looking for a more authentic taste and willing to spend more time, fresh yeast or sourdough ( which is nothing more than using the previous dough, with its yeast load) may be the best option. The final choice will depend on your personal preferences, the recipe you are following, and the amount of time you have available.
- Fresh yeast is great for artisan breads and doughs with long fermentation times.
- Active dry yeast is often used for homemade breads or traditional baking recipes.
- Instant dry yeast is often used in quick breads, when you are short on time, and in commercial bakeries.