Antioxidant activity of protein hydrolyzates from by-products of the food industry

Hydrolyzate was obtained from cracklings (CEH) using Alcalase. Hydrolyzates were also prepared from cracklings (CAH) and chicken feathers (FAH) using hydrochloric acid. Antioxidative activity of the above hydrolyzates was evaluated by spectroscopic methods. The oxidative stability of lard with the addition of hydrolyzates was tested using a Rancimat and an Oxidograph apparatus set at 110C Hydrolyzates were analyzed using PP-HPLC method. The highest antioxidative efficacy of hydrolyzates examined was found for CEH at an addition level of 0.25 and 0.50% N-tot using spectroscopic methods. The antioxidant effect of BHT at a level of 0.01% N-tot was stronger than that of all Hydrolyzates tested The strongest antioxidant effects evaluated using the Rancimat method were noted for both acid hydrolyzates applied at level of 0.5% N-tot. Antioxidant activity of BHT added to lard at a 0.02% level, was lower than those of CEH, CAH and GAH at a level of 0.5% NO,. Superior antioxidant activity determined under conditions of the Oxidograph test was observed for CAH at a level of 0.5% N-tot. Antioxidant activities observed from synthetic antioxidants added to lard at a 0.02% level were higher than those from any of the three hydrolyzates tested. RP-RP-HPLC chromatograms of the acid hydrolyzates (CAH and FAH) were similar. A completely different looking chromatogram was obtained for the enzymatic hydrolyzate (CEH). It was characterized as having many, not well-separated peaks originating from peptides.