Hydrolyzed proteins are a mixture of more or less complex amino acids and peptides obtained from the hydrolysis of an animal protein source (e.g. whey protein, egg protein) or vegetable (e.g. soy protein).
The hydrolysis process follows what happens in the human stomach and intestine, where specific enzymes - pepsin, trypsin, protease, peptidases - break down food proteins into ever smaller peptides, until the individual amino acids that compose them are obtained.
- Two amino acid molecules form a dipeptide, three a tripeptide, and so on
- If the peptide contains less than ten amino acids it is called oligopeptide
- As an indication, we speak of polypeptide when this chain is made up of less than 100 amino acids, and of proteins when the number of individual amino acid units exceeds this threshold.
Note: the intestine is able to absorb even small peptides (di-, tri- and oligo-peptides), which even seem to be absorbed more easily than free amino acids.
What are they for
Hydrolyzed proteins are also known as predigested proteins. Although the hydrolysis process can take place in various ways (for example by providing heat, or strongly acidic or basic substances), the hydrolyzed proteins intended for sports integration and clinical applications are obtained by enzymatic hydrolysis; this allows to preserve some important components that would be inactivated by acids or heat, and to improve the taste.
In particular, there are two main fields of application of hydrolyzed proteins:
- the formulation of hypoallergenic products, such as formulas intended for infants who are allergic or intolerant to milk proteins
- the formulation of protein supplements for athletes, which compared to traditional protein powder supplements have two main advantages:
- or are better tolerated in the gastrointestinal tract, especially by the most sensitive subjects who complain of bloating, flatulence and abdominal pain following the integration of traditional powder products
- o theoretically require shorter digestion times, ensuring faster absorption after ingestion which results in a greater insulin peak (greater insulinotropic effect, see insulin index) and a more rapid increase in amino acid levels in the blood ; consequently, hydrolyzed protein supplements are particularly indicated in the post-workout to accelerate recovery and take advantage of the so-called anabolic window. By increasing the release of insulin, the hydrolyzed proteins taken together with an adequate dose of liquids and carbohydrates increase the speed of muscle glycogen recovery after exercise. From a study (Human insulitrophic response to oral ingestion of native and hydrolysed whey protein - Orla Power, Philip Jakeman, Aine Halihan) which compared some metabolic effects of whey protein isolate with hydrolyzed whey proteins and it emerged that:
- the gastric emptying rate is almost identical
- the insulin peak is later after the ingestion of hydrolyzed proteins (60 minutes compared to 40 minutes for traditional protein isolates)
- the insulin peak determined by the hydrolysed proteins is however more intense (28%) and consistent (area under the curve over three hours 42% higher).
Note: the more the hydrolysis process is pushed, the greater the bitterness problems of the product become, given that some amino acids (such as tryptophan, phenylalanine, tyrosine and leucine) have a typically bitter taste. A well-known hydrolyzed protein raw material (Carbery Optipep TM) claims a degree of hydrolysis (DH) ranging from 5 to 40%.