Properties of chicken protein isolate/fish gelatin blend film incorporated with phenolic compounds and its application as pouch for packing chicken skin oil

Abstract

Chicken protein isolate (CPI)/fish skin gelatin (GE) blend films containing gallic acid (GA) or tannic acid (TA) at varying concentrations (0, 0.375, 0.75, 1.5 and 3.0 %, w/w based on protein content) were characterized. Incorporation of phenolics generally increased (p < 0.05) tensile strength and elongation at break, and decreased (p < 0.05) solubility of resulting films. However, higher (p < 0.05) a*-, b*- and ΔE*-values and lower (p < 0.05) seal strength and seal efficiency were noted for all films containing phenolics, especially at higher concentrations. CPI/GE films containing TA possessed more compact structure and lower (p < 0.05) water vapor permeability than those added with GA. However, films containing 0.75 % GA possessed the highest DPPH radical scavenging activity and were used to form pouches for packing chicken skin oil (CS-O). Less peroxide value (PV), thiobarbituric acid reactive substances (TBARS) and volatile compounds were attained, while polyunsaturated fatty acids were more retained for CS-O packaged in CPI/GE pouches containing 0.75 % GA after 15 days of storage than those packaged in CPI/GE pouches without GA or commercial pouches. Incorporation of 0.75 % GA improved mechanical properties and antioxidant activity of CPI/GE blend film, thus highlighting the potential of the resulting pouches as active food packaging.