The study on microwave assisted enzymatic digestion of ginkgo protein

Microwave-assisted enzymatic digestion (MAED) technique was applied for ginkgo protein digestion with both free and immobilized enzyme. Under the optimized conditions of MAED (0.01 g/mL substrate concentration of bromelain, 4500 U/g enzyme/ginkgo protein, 30 min, 300 W microwave power), a higher digestion rate (7.50%) and a significant increase in antioxidant activity (72.7 mg/g) were obtained in contrast with the conventional methods. With the optimized digestion conditions (0.625% glutaraldehyde (v/v), 0.4 mg/mL initial concentration of bromelain and 4 h of immobilization), the activity and effectiveness factor of immobilized bromelain were respectively 86 U and 81.6%. The results of ginkgo digestion by applying MAED indicated that the digestion rate of immobilized bromelain obtained by MAED method (6.41%) was comparable to that of free bromelain in the conventional digestion (8.13%). In both case with immobilized and free bromelain while applying MAED, a homogeneously abundant distribution of peptide fragments (from 7.863 Da to 5856 Da) and a few different peptide profiles were found. This report brings in conclusion that applying MAED with immobilized enzyme has the potential to obtain the highest number of antioxidant activity peptides.