PROCESS OPTIMIZATION FOR PRODUCTION OF WHEY PROTEIN HYDROLYSATE FROM CHEESE WHEY HAVING ANTIOXIDANT PROPERTY
Oxidative stress, the increased production of reactive oxygen species and reactive nitrogen species combined with overtaking endogenous antioxidant defense mechanisms, is a significant causative factor for the initiation or progression of several life style mediated diseases. Dietary consumption of antioxidants appears to benefit endogenous antioxidant defense strategies in the fight against oxidative stress. Cheese whey is a rich by-product in nutritional terms: possessing high biological value components, excellent functional properties, and an inert flavour profile. In particular, biological activities of whey proteins and their hydrolysates have received more attention in recent years. Peptides generated from whey protein hydrolysis have antioxidant properties and it depends on the protease specificity as well as hydrolysis conditions. Currently, data on the hydrolysis conditions for the direct production of hydrolysate from whey is lacking. So in the present study, mozzarella cheese whey was ultrafiltrated to concentrate the protein content and the retentate after preheat treatment was hydrolyzed using commercial food grade enzyme alcalase. Response Surface Methodology (RSM) was applied to optimize the hydrolysis conditions, including incubation time, hydrolysis temperature and pH with the purpose of obtaining the most powerful antioxidant hydrolyzate from whey proteins. A central composite circumscribed (CCC) design was employed to study the effect of the experimental variables on the antioxidant activity determined by 2, 2’-azinobis (3-ethylenebenzothiazoline-6-sulphonic acid) (ABTS•+) radical scavenging activity and the parameters of the model were estimated by multiple linear regression. The highest antioxidant activity (1.18±0.015μM of trolox/ mg of protein) was found in retentate hydrolyzed for 8 h at pH 9 and temperature 55ºC. Seven β-lactoglobulin derived peptides were identified by RP-HPLC-MS/MS in this hydrolyzate. Amino acid composition of the peptides DTDYK f(96–100) and VLDTDYK f(94–100) indicating their important contribution on antioxidant property of whey protein hydrolysate (WPH) was evaluated. Hydrolysis of ultrafiltrated retentate of whey can be an energy and cost effective method for the direct production of WPH from whey compared to the industrial production of WPH from Whey protein concentrate. This study suggests that WPH with good nutritional and biological properties can be effectively used in health promoting foods as a biofunctional ingredient.
Whey Protein hydrolysate, Antioxidant property, Bioactive peptides