Physicochemical characteristic of modified edible film made from gelatine of sea bass (Lates calcarifer) residue with palmitic acid and soybean protein isolate treatment

Abstract

The use of fish waste as raw material in producing gelatin becomes important when it is related to the halal perspective. Sea bass skin contains high protein, especially collagen protein which can be used as the main component of edible film. An edible film made from gelatin of fish skin usually lacks water vapour transmission due to its hydrophilic properties. Modification of formula in producing an edible film from fish gelatin with the addition of lipid such palmitic acid (PA treatment) and soybean protein isolate (SPI treatment) can affect the characteristics of the edible film resulted. This study was aimed to evaluate the chemical (solubility, water vapour permeability) and physical characteristics (thickness, tensile strength, per cent elongation, SEM) of an edible film made from gelatin with the addition of palmitic acid and soybean protein isolate with different concentration. The results showed that edible films with SPI addition yield the best film thickness (<2.5 mm) while PA addition resulted in better tensile strength of the films (>3.92 MPa) according to the Japanese Industrial Standard. The per cent elongation of both films with PA (21.3-34.44%) and SPI (36.06-117.53%) addition decreased with increasing concentration, but SPI generally gave higher elongation compared to PA. The addition of SPI gave lower solubility and higher water vapour transmission values compared to PA, however, the addition of 4.5% of PA gave the lowest water vapour transmission (5.416 g/m2 h). Therefore, the best treatment in this study was concluded to be 4% of SPI addition based on the best thickness, per cent elongation, water vapour transmission and solubility results.