Protein Hydrolysates from Pacific White Shrimp Cephalothorax Manufactured with Different Processes: Compositions, Characteristics and Antioxidative Activity

Hydrolysates from Pacific white shrimp (Litopenaeus vannamei) cephalothorax were prepared using various hydrolysis processes, and their chemical composition, characteristics as well as antioxidative activity were studied. Those processes consisted of autolysis (AU), hydrolysis using Alcalase at 0.5% (0.5A) or 1.0% (1.0A) and autolysis, followed by Alcalase hydrolysis at 0.5 and 1.0% (AU+0.5A and AU+1.0A). All the hydrolysate samples had higher protein contents (86.04-89.24%) and lower amounts of ash (7.46-11.26%) and lipids (0.43-0.64%), compared to those of cephalothorax (P<0.05). The highest yield (54.04%) and protein recovery (84.15%) were observed in the AU+1.0A sample, which had the maximum degree of hydrolysis (DH) (44.93%) (P<0.05). All the hydrolysates had glutamic acid/glutamine (115.80-121.69 mg/g dry sample), aspartic acid/asparagine (84.04-90.28 mg/g dry sample), arginine (63.27-68.62 mg/g dry sample) and leucine (58.67-68.07 mg/g dry sample) as the dominant amino acids. Based on gel filtration chromatography, the hydrolysates with higher DH showed higher proportions of smaller peptides (<1355 Da). When the antioxidant activities of the hydrolysates were determined, the AU+1.0A sample had the highest ferrous ion chelating activity, ABTS radical scavenging activity and ORAC value, compared to the others (P<0.05). However, the highest ferric reducing antioxidant activity and DPPH radical scavenging activity were obtained for the 1.0A and AU samples, respectively (P<0.05). Furthermore, the AU+1.0A sample showed higher inhibitory activity against DNA damage induced by peroxyl radicals than the 1.0A and AU samples. Therefore, different hydrolysis processes directly affected the protein recovery, chemical composition and antioxidant activities of the hydrolysates from shrimp cephalothorax.