Yogurt, Lactic and Prebiotic Ferments

they are not to be confused with prebiotics. These substances, while similar in name, are very different nutritional factors.

Lactic ferments are living organisms; the prebiotics, on the other hand, are inanimate molecules mainly belonging to the chemical group of carbon hydrates.


The name "lactic ferments" is justifiable by the fact that these probiotic microbiological strains (which we will specify better later) multiply with great ease in milk or relative whey, acidifying it and giving rise to various fermented foods, of which the best known is without "other yogurt.

Lactic and prebiotic enzymes are however interconnected, both from a purely biological point of view, and as regards the physiological, medical and nutritional aspects; later on we will understand better why.

. As anticipated in the introduction, the term "lactic ferments" arises from the fact that these beings live and replicate successfully in milk and relative whey.

The life cycle of probiotics is perpetuated above all in conditions of:

  • Abundant water
  • Room temperature
  • neutral or slightly basic pH
  • Lack or lack of oxygen.

The metabolism of probiotics is called "lactic fermentation" because, starting from lactose (sugar disaccharide typical of milk) and in the absence of oxygen (anaerobiosis), it produces considerable concentrations of lactic acid. Secondly, certain amino acids and lipid compounds are also degraded in milk, with the release of other molecules.
There are various species of lactic ferments, belonging mainly to the genera Lactobacillus, Bifidobacterium, Eubacterium and few Streptococcus.

What are Prebiotics?

Prebiotics are molecules of various kinds which, having reached the large intestine (colon), are metabolized by the intestinal bacterial flora, favoring its metabolism and numerical growth.

These are mostly water-soluble fibers (which dissolve in water to form a gel) and carbohydrates (available and unavailable) contained in foods of plant origin. In fact, prebiotics can be divided into two categories:

  1. Digestible and nutritious also for man; they are carbohydrates which, not absorbed in the small intestine (for example due to an excess of food), reach the large intestine and are metabolized by bacteria
  2. Non-digestible and exclusively available to bacteria; it is water-soluble fibers and unavailable carbohydrates that reach the lumen of the colon unscathed.
  • Nutrient production (especially vitamin K and certain B vitamins)
  • Optimization of the nutritional absorption of minerals (such as calcium)
  • Production of "nutritive" molecules for the mucous cells of the large intestine (acetic, propionic and butyric acid).
  • Hence, the human organism has a vested interest in keeping the colonic bacterial flora population healthy. How?

    1. Feeding it, to make it multiply inside the intestinal lumen.
    2. Possibly introducing other microorganisms orally.

    We have already specified that lactic ferments are typical microorganisms of fermented milk-based derivatives, such as yogurt. This suggests that these foods are the optimal source of probiotics in the diet.

    On the other hand, this is not exactly the case and in the paragraph dedicated to yogurt we will find out more why.

    What are prebiotics used for?

    Considering that lactic ferments make up a large part of the intestinal bacterial flora and that the latter feed effectively on lactose, we might be led to believe that milk sugar is an excellent prebiotic. This is not exactly the case. In fact, in ordinary people lactose is mainly digested and absorbed; this means that it does not reach the intestinal bacterial flora.

    On the contrary, in the so-called "intolerant", lactose arrives intact in the "large intestine (due to the lack of digestive enzymes lactase), where it is processed by triggering unwanted symptoms (flatulence, diarrhea, cramps, etc.).

    Unlike lactose, unavailable carbohydrates and soluble fibers (contained above all in vegetables, fruits, legumes pulp, etc.), if taken in the right quantities, produce a "less impetuous" and therefore beneficial effect.
    This is why "selected and isolated" prebiotics:

    • They are often added to probiotic foods to improve the survival of lactic ferments and provide a specific substrate for the intestinal bacterial flora
    • They constitute specific supplements to improve the trophism of the intestinal bacterial flora.

    The synergistic action for health is exploited in symbiotic foods which are, by definition, products containing a mixture of probiotics and prebiotics. This category of foods maintains the same therapeutic indications as probiotics. See: inulin.

    they also operate in mutual synergy with a protosymbiotic mechanism: in the early stages it Streptococcus creates the conditions for the Lactobacillus the work of splitting lactose is reproduced and carried out.

    The microbial cultures necessary for the preparation of yogurt have an optimal development at temperatures between 42 and 43 ° C.

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