Probiotic foods are fermented foods, that is, foods in which bacteria or microorganisms convert sugar molecules (carbohydrates) into lactic acid through a process of lactic acid fermentation.
As a result of the lactic acid fermentation process, a food is obtained that is rich in probiotic microorganisms as well as other products resulting from fermentation, both of which are beneficial to the body.
Some examples of probiotic food or fermented food are probiotic yogurts, kefir, kombucha tea or sauerkraut.
Yogurt is perhaps the best-known probiotic food, although we are so used to have it that we may not be aware that it is a natural probiotic.
It is made by a process of lactic acid fermentation from milk to which two bacterial species are added, namely Lactobacillus delbrueckii subsp. bulgaricus and Streptococcus thermophilus.
If the yogurt is pasteurized after lactic acid fermentation, the bacteria will die as a result of the heat and the product will no longer have probiotics, that is, it will not be a probiotic yogurt and will not have its beneficial effects.
Yogurt brings great benefits to the body:
As it is a dairy product, it provides calcium as well as vitamins such as riboflavin (vitamin B2) and cyanocobalamin (vitamin B12). It provides minerals such as Magnesium, Phosphorus and Potassium with a positive influence on blood pressure (1)
Yogurt has a great contribution of proteins, thus impacting in a greater sensation of satiety helping us to maintain the control of the weight (2).
Yogurt can be eaten by people with lactose intolerance since, during fermentation, it is precisely this sugar that is transformed into lactic acid, giving the yogurt its characteristic flavor and reducing the original lactose level of the milk to a minimum.
Kefir milk is another well-known fermented product. Its origin dates back to the Caucasian region and thousands of years ago.
Kefir milk is a dairy product, similar to yogurt, although somewhat more liquid and a little sourer. It is also obtained by fermentation of cow’s, goat’s or sheep’s milk, but in this case using kefir grains, a culture with a similar appearance to cauliflower, formed by a mixture of yeasts and bacteria and which, in a symbiotic way, are responsible for carrying out the fermentation process.
How to make Kefir Milk
It is usually prepared at home, in a traditional way, by adding milk to a quantity of kefir grains and leaving the mixture at room temperature, during about 24 hours, to develop the fermentation. The duration of the process will depend on the temperature of the room so that the more heat, the faster the fermentation process.
Once the process is finished, the kefir grains are removed from the fermented milk so that the liquid obtained is already the kefir milk.
The extracted kefir grains can be used to ferment more milk. These grains, which in each fermentation process usually grow around 5%, can be obtained through friends or acquaintances as they always have an “overproduction” due to the growth they experience after each production process.
However, you can also find in the market both kefir grains as well as the appropriate accessories to make kefir at home:
Kefir has a different fermentation process than yogurt because it is done by different bacterial species and yeasts are also involved. This difference means that the fermentation process is not only lactic, there is also an alcoholic fermentation so that the kefir obtained has a small proportion of ethanol, less than 1%.
As for the beneficial properties of kefir, there are numerous studies that claim to have antimicrobial, antitumor, immunomodulatory properties and, like yogurt, also helps the digestion of lactose in intolerant people (3).
With its content in probiotic microorganisms, it contributes to improve our intestinal microbiota by repopulating species that for some reason (e.g. treatment with antibiotics) have been reduced. The consumption of kefir increases the presence of lactobacilli in the intestinal mucosa reducing the presence of enterobacteria and clostridium (4).
Kombucha tea is a millenary drink of Chinese origin, from approximately 200 B.C. although it was later used as medicine in Japan, Russia and Eastern Europe. Although it is usually prepared at home in a traditional way, nowadays in the market we can find several kombucha drinks
This drink is a fermented tea prepared from black or green tea to which sugar is added and a SCOBY, a gelatinous mixture containing the microorganisms (bacteria and fungi) that will carry out the fermentation process by consuming all the sugar we have added and converting it into acetic acid, ethanol and CO2.
The SCOBY, acronym for Symbiotic Culture Of Bacteria and Yeast, contains a combination of microorganisms that act in a symbiotic way growing by consuming the sugar added to the tea. As a result, at the end of the process a new “scoby” (“the son”) will have been created that can be used in future fermentations. SCOBY contains bacteria of the genera Acetobacter, Gluconobacter and yeasts of the genera Saccharomyces and Zygosaccharomyces among others.
Once fermented, the resulting drink contains a mixture of organic acids (acetic, gluconic, lactic), amino acids, vitamins B and C, some ethanol (less than 1%) and minerals such as Copper, Iron, Manganese or Zinc (5).
For the people who prepare it at home, the scobies can be obtained through friends or acquaintances who are already preparing kombucha tea and who give you part of their surplus that they generate in each fermentation although it is also available through some online stores:
Benefits of Kombucha Tea
As for the benefits of Kombucha tea, although its benefits have been passed down from generation to generation for thousands of years, the reality is that today there are no scientific studies conducted on humans about its benefits.
Studies conducted in vitro and in animals have associated Kombucha tea with health benefits among which are antimicrobial properties, beneficial effects on gastrointestinal and hepatic functions, stimulation of the immune system, antioxidant, detoxifying, etc.
However, kombucha tea is now considered a “healthy” drink and a source of pharmacologically active molecules because of its antioxidant components and possible health benefits (6).
Food fermented from cabbage. It is of Central European origin. As for the sauerkraut recipe, it is made by fermenting cabbage from the microorganisms that are naturally present in it.
Normally it is not homemade sauerkraut, but it is bought already elaborated:
Sauerkraut is very nutritious. It contains proteins, carbohydrates, fiber, vitamins B6, C and K as well as various minerals (Iron, Manganese, Potassium among others).
With its fermentative process there is a growth of microorganisms of which many of them are probiotics, although not all of them are. It is precisely this presence of probiotics that makes sauerkraut, in addition to its nutritional characteristics, a very healthy food.
Not all probiotics have the same beneficial properties. In the case of sauerkraut, almost 30 strains of different species of probiotics have been identified, which makes them complement each other since what one of them does not do, another strain can do
Degree in Pharmacy – Universidad Complutense de Madrid.
Specialist in Chemical Analysis – Universidad Complutense de Madrid.
Master in Pharmaceutical Industry – CESIF Madrid.
Diploma in Ophthalmic Optics – Universidad de Barcelona
Diploma in Optics and Optometry – Universidad de Granada