Effect of Microwave Treatments on Antioxidant Activity and Antigenicity of Fish Frame Protein Hydrolysates

Protein solubility, protein recovery, antioxidant activity, and antigenicity of microwave pretreatment and/or microwave-assisted hydrolysis of trout frame protein hydrolysates was investigated. Treatments consisted of (1) microwave pretreatment at low temperature (55 A degrees C) followed by conventional enzymatic hydrolysis or (2) high temperature (90 A degrees C) followed by conventional enzymatic hydrolysis; (3) microwave pretreatment at high temperature (90 A degrees C) followed by microwave-assisted enzymatic hydrolysis, and (4) no microwave pretreatment followed by microwave-assisted enzymatic hydrolysis. Compared to controls, microwave treatments significantly improved (P < 0.05) protein solubility, protein recovery, degree of hydrolysis, and 2,2'-azino-bis(3-ethylbenzthiazoline-6-sulphonic acid) free radical scavenging radical scavenging activity. Decrease of antigenicity (55-93 %) was obtained in all microwave-treated samples. Based on the results of this study, the use of microwave pretreatment for 5 min at 90 A degrees C, followed by conventional enzymatic hydrolysis with alcalase for 2-10 min was the best treatment condition to produce fish peptides with antioxidant activity and the lowest immunoreactivity. These peptides have potential to be applied as hypoallergenic ingredients in food formulations and nutraceuticals.