Protein hydrolysates are used in the medical and food industries, as well as in microbiology. Their production is based on the breakdown of organic compounds. The resulting composition is more easily absorbed by the human and animal body, has a high nutritional value. These compounds are especially important in the manufacture of hypoallergenic infant formula.
Description
Protein hydrolysates are substances resulting from the decomposition of protein by reaction with water. Cleavage occurs in the presence of catalysts: acids, alkalis or enzymes. As a result, the peptide bonds of the high molecular weight chain are destroyed, and the final product is a complex mixture consisting of individual amino acids, their sodium salts, and polypeptide residues. This process is exemplified by the tripeptide shown in the picture below.
Hydrolysates of various types of proteins obtained at the same depth of their cleavage have the same composition. These substances are valuable biologically active compounds, since amino acids are the main source of nutrition for tissues and their “building material”, and peptides are involved in the synthesis of amino acids, play an intermediary role in metabolic processes and serve as immunomodulators.
The main components of protein hydrolysates are shown in the illustration below.
In the final product, amino acids such as:
- glutamine;
- aspartic;
- pyrrolidine-α-carboxylic (proline);
- 2-amino-5-guanidinopentane (arginine);
- 2-aminopropane (alanine);
- 2-amino-4-methylpentanoic (leucine).
Properties and features
Protein hydrolysates have the following biological characteristics:
- high physiology;
- good digestibility with various methods of introduction into the body;
- lack of toxicity, antigenicity, allergic reactions;
- non-hormonal nature of the compounds.
The main physical and chemical criteria for the use of these substances are:
- viscosity;
- ability to dissolve in water;
- emulsification;
- gel and foaming.
These parameters depend on the type of feedstock, the splitting method, the reagents used, and the process conditions. The following features are characteristic of certain types of hydrolysates:
- soy products of hydrolysis are poorly soluble at pH = 4-5.5;
- whey, casein, meat hydrolysates show good thermal stability in the presence of divalent metal salts when heated to 130 ° C;
- compounds derived from fish waste dissolve well even with a low degree of degradation;
- deep hydrolysis, used to obtain hypoallergenic compositions, leads to almost complete loss of emulsifying properties (except for hydrolysates based on fish protein);
- in the presence of neutral alkali metal salts, the solubility of protein substances changes (for example, potassium ions lead to its increase);
- the viscosity of the hydrolysates is much lower compared to the original proteins, and when they are heated, gel structures do not form. This favorably affects the creation of foods with a high content of valuable nitrogen compounds.
Kinds
The classification of protein hydrolysates is carried out according to 2 main criteria. Namely:
- By type of raw material - fish, soy, dairy, casein, whey, soy, meat, egg. Hydrolysis of protein wastes from various industries is one of the effective ways of their disposal.
- According to the processing method - deep, medium (5-6 days) and low (5-72 hours) degree of cleavage (amino acid content of at least 50, 25 and 15%, respectively).
For the manufacture of therapeutic nutrition and therapeutic agents, compounds based on cow's milk (whole protein, curdled milk or whey) obtained by enzymatic cleavage are most often used. Animal protein hydrolysates are used in microbiology, virology, and veterinary medicine. Soy products also have hypoallergenic and hypocholesterolemic properties.
Whey protein hydrolysates have an amino acid composition similar to that in human muscle tissue, and in terms of the number of essential amino acids they surpass all other raw materials of animal and vegetable origin.
Getting
There are 3 main methods for the production of these compounds:
- Acid hydrolysis using hydrochloric or sulfuric acid as a catalyst. The process occurs when heated to 100-130 ° C and a pressure of 2-3 atmospheres. This method is the most common, because thanks to it, a deep degree of cleavage is achieved and the risk of bacterial contamination is eliminated. The duration of the reaction is 3-24 hours. The best efficiency is in relation to fibrillar proteins. The disadvantage of this method is that in doing so, many valuable amino acids, vitamins are destroyed and toxic by-products are formed, which require additional purification.
- Alkaline hydrolysis. This method is used less often (mainly in the processing of shellfish and fish), because an undesirable transformation of amino acids occurs, lantibiotics (antimicrobial polypeptides of bacterial origin) are formed.
- Enzymatic hydrolysis. Free from the drawbacks of the two previous technologies and is highly efficient. The process occurs at a low temperature (25-50 ° C), acidity of the medium, close to neutral, and atmospheric pressure. This allows you to save the largest number of biologically active components.
The following substances are used as enzymes:
- digestive pancreatin, trypsin, chymotrypsin (especially effective in the processing of meat and blood);
- plant compounds: ficin, papain, bromelin;
- bacterial enzymes: protosublitin, rapidose;
- substances synthesized with the help of fungal cultures: protorizorins, rimoproteline, protelin and others.
A complete protein hydrolyzate contains a complete set of amino acids in the optimal ratio, which is especially important for dietary, medical and veterinary purposes. Such a composition can be obtained by deep processing of raw materials, with many hours of boiling the solution in the presence of acid catalysts.
Application
Protein hydrolysates are used in industries such as:
- Medical (manufacturing of drugs, medical nutrition for the prevention of protein deficiency, therapy of pathologies of musculoskeletal and connective tissue, metabolic disorders).
- Food (production of semi-finished meat products, gelatin, wines, edible films and coatings, canned fish, sauces, bakery products, high-calorie additives for athletes).
- Microbiological (manufacturing of diagnostic nutrient media).
- Feed production.
Agriculture
As a feed additive, protein hydrolysates from meat, fish, blood and milk are used in the following cases:
- to increase nonspecific immunity in weakened, sick animals;
- in order to obtain a greater gain;
- as an adaptogen in stressful situations and in the presence of risk factors (high morbidity and mortality among birds and animals);
- with metabolic disorders and developmental delays.
In addition, enriched feeds make it possible to improve the quality of fur in fur animals.
Milk formula: protein hydrolysates in baby food
Cow's milk, which is the main raw material for infant formula for breastfeeding, can cause allergic reactions. The highest activity in this regard is possessed by high molecular weight whey proteins: alpha-lactoalbumin, beta-lactoglobulin and casein.
The most effective way to reduce the allergenicity of milk at present is to obtain milk protein hydrolysates using enzymes and their subsequent ultrafiltration. Such mixtures contain low molecular weight peptides with a molecular mass of less than 1500 D, and their tolerance among children with allergies is at least 90%.
By the type of protein that is used to make the dairy product, the mixtures are divided into casein, whey (the most common), soy, mixed. They are also prescribed for malabsorption of nutrients in the intestines and for the prevention of food allergies.