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

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 Delta E*-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.

Automated summary

Chicken protein isolate/fish skin gelatin blend films with varying concentrations of gallic acid or tannic acid were found to exhibit improved mechanical properties, antioxidant activity, and potential for packaging chicken skin oil. Incorporation of 0.75% gallic acid showed the highest antioxidant activity and improved retention of polyunsaturated fatty acids in the packaged oil. These findings suggest the potential of the resulting pouches as active food packaging.