Received: October 14, 2016; Revised: January 4, 2017. Accepted: February 5, 2017. Published online February 23, 2017.
Objective: The objective of this study was to optimize ultrasonic-assisted enzymatic hydrolysis conditions, including enzyme-to-substrate (E/S) ratio, pH, and temperature, for producing porcine liver hydrolysates (PLHs) with the highest 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radical scavenging activity by using response surface methodology (RSM).
Method: The study used RSM to determine the combination of hydrolysis parameters that maximized the antioxidant activity of our PLHs. Temperature (40°C, 54°C, and 68°C), pH (8.5, 9.5, and 10.5), and E/S ratio (0.1%, 2.1%, and 4.1%) were selected as the independent variables and analyzed according to the preliminary experiment results, whereas DPPH free radical scavenging activity was selected as the dependent variable.
Results: Analysis of variance showed that E/S ratio, pH, and temperature significantly affected the hydrolysis process (P < 0.01). The optimal conditions for producing PLHs with the highest scavenging activity were as follows: E/S ratio, 1.4% (v/w); temperature, 55.5°C; and initial pH, 10.15. Under these conditions, the degree of hydrolysis, DPPH free radical scavenging activity, ferrous ion chelating ability, and reducing power of PLHs were 24.12%, 79%, 98.18%, and 0.601, respectively. The molecular weight of most PLHs produced under these optimal conditions was less than 5,400 Da and contained 45.7% hydrophobic amino acids.
Conclusion: Ultrasonic-assisted enzymatic hydrolysis can be applied to obtain favorable antioxidant hydrolysates from porcine liver with potential applications in food products for preventing lipid oxidation.
Asian-Australasian Association of Animal Production Societies(AAAP)
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