Protein hydrolysate as a source of bioactive peptides in diabetic food products

Protein hydrolysates are a promising active component in specialized food products. Due to the presence of bioactive peptides with enzyme inhibiting activity in their composition, protein hydrolysates exert different physiological effects. The aim of the research was to establish the potential hypoglycemic activity of the protein hydrolysate of broiler chicken stomachs in whey and to develop a beverage on its basis for patients with diabetes mellitus. Protein hydrolysates obtained from microbial fermentation of muscular stomachs of broiler chickens in whey were assessed by UHPLC coupled to mass-spectrometry. Using the BioPEp database, the molecular weight distribution of peptides in the hydrolysates was determined. In addition, bioactive peptides showing the inhibitory activity toward enzymes dipeptidyl peptidase‑4 and amylase were revealed. Based on the obtained hydrolysates, recipes of beverages for patients with diabetes mellitus were modeled in the Excel software program with regard to the recommendations for nutrition of this population group. According to the obtained recipes, beverages were produced in the laboratory conditions and their taste was assessed. An effect of the beverage on glucose reduction in the blood of laboratory animals was assessed upon single peroral administration with a dose of 1.3 ml before the main meal. The results of the investigation of the peptide composition of protein hydrolysates showed the presence of bioactive peptides (SY, VW, SW) in them with the inhibitory activity toward enzymes dipeptidyl peptidase‑4 and amylase confirmed by the BioPep database. The highest amount of the above indicated bioactive peptides (37.1 mg/100 g hydrolysate) was in the protein hydrolysate produced by fermentation of raw materials with propionic acid bacteria. The beverage produced on the basis of the protein hydrolysate and lemon juice was more acceptable for consumers in terms of taste than the beverage with the taste of cacao. The results of the in vivo trials showed that the beverage based on the protein hydrolysate was effective in reducing sugar in blood of both healthy rats and rats with diabetes mellitus. The blood sugar level in the healthy animals of the G1 group (without using the beverage) increased by 151% relative to the initial values, which was a higher value compared to the G2 group (with the use of the beverage), where an increase was 87%. A more significant growth in the blood sugar level (61% relative to the initial values) was also observed in the ill animals in the G3 group (without using the beverage), while this increase was 46% in the G4 group (with the use of the beverage). Thus, the results of the study show the prospects of using the protein hydrolysates from broiler chicken stomachs in whey as an active hypoglycemic component in beverages for patients with diabetes mellitus. However, more profound research is necessary including studies on the representative group of patients.