Abstract:

As a high quality protein resource that contains 18 amino acids including 8 essential ones accounting for 40% of total amino acids, silkworm pupa protein is more nutritional than soybean protein isolate. However, silkworm pupa protein is generally processed into powder with poor water solubility and unfavorable odor, which greatly retards its application in food industry. Silkworm pupa protein was hydrolyzed with five proteases (Alcalase, Flavourzyme, Protamex, Papain and Trypsin) respectively. Alcalase was confirmed as an optimal enzyme preparation to prepare silkworm pupa polypeptide in terms of degree of hydrolysis (DH) of material and DPPH· scavenging activity of hydrolysates. The enzymatic hydrolysis procedure was optimized using orthogonal array method and the corresponding product was subjected to further analysis of antioxidant activity such as reducing power and O2·, ·OH and DPPH·scavenging activities. The optimal Alcalase-catalyzed hydrolysis parameters were as follows: substrate concentration 4%, enzyme/substrate concentration ratio 2:100, temperature 60 ℃, pH 4, and hydrolysis duration 4 h, and under such conditions a DH of 28.2% was achieved. The hydrolysis product could effectively scavenge DPPH·, O2· and OH· radicals, suggesting its strong antioxidant activity.

Key words: silkworm pupa protein, hydrolysis, antioxidant activity