ANTIOXIDANT ACTIVITY OF BOVINE MILK WHEY HYDROLYSATES OBTAINED BY ENZYMATIC ACTION

Resumen

Bovine Milk Whey (MW) is the primary by-product of the dairy industry and possesses highly beneficial nutritional and biological properties, making it economically and technologically valuable. MW was obtained from panela cheese and hydrolyzed with two proteolytic enzymes, Heliozym and HT Proteolytic 200, at different times (0, 0.25, 0.5, 1, 2, 3, 4, 6 h). The resulting hydrolysates were characterized through physicochemical analyses, Fourier-transform infrared spectroscopy (FTIR), isoelectric point (IP), molecular weight, thermal properties assessment, and evaluation of antioxidant activity using 2,2’-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) and 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical inhibition assays. The composition of native bovine MW was 0.15 % fat, 0.43 % protein, 5.19 % lactose, and 0.36 % minerals. Sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) analysis revealed characteristic bands corresponding to β-lactoglobulin (18 kDa), α-lactalbumin (14.0 kDa), bovine serum albumin (BSA) (66.4 kDa), lactoferrin (75 kDa), immunoglobulin G (IgG, ~160 kDa), and protease peptone (Pp) (25–30 kDa). The IP (isoelectric point) of native whey shifted from 4.58 to 3.97 after 3 h of treatment with Heliozym. Conversely, after 4 h, the HT Proteolytic 200 sample showed an IP of 8.94. Thermal analysis indicated that the endothermic curves of α-lactalbumin and β-lactoglobulin were not detected, suggesting complete protein degradation after 6 h. Luminosity values varied significantly (p < 0.05) during enzymatic treatment, with notable differences between hydrolysates resulting from Heliozym and HT Proteolytic 200 action. Antioxidant activity showed maximum ABTS radical inhibition at 6 h of treatment, with values of 97.98 ± 0.85 % for Heliozym and 79.74 ± 2.4 % for HT Proteolytic 200. For DPPH radical inhibition, peak values were 36.33 ± 1.61 % for HT Proteolytic 200 and 41.31 ± 3.17 % for Heliozym after 6 h. The final properties of whey hydrolysates were influenced by substrate pretreatment, hydrolysis conditions, temperature and pH, and the specific enzyme used.