Effect of pH on the properties of protein-based film from silver catfish (Pangasius sp.) mince

Abstract

The effects of pH of film-forming solutions from unwashed silver catfish mince on film formation, thickness, mechanical properties, water vapour permeability, colour, light transmission, transparency, film solubility and biodegradability were investigated. It was found that film from silver catfish mince had been successfully formed at pH 1-4 and pH 9-12. The thickness, tensile strength, elongation at break, water vapour permeability and film solubility were significantly different for films obtained (p > 0.05). Higher thickness was obtained for the film prepared at pH 11 and pH 12. The study showed the resulting films had improved water vapour barriers than other fish mince films. Tensile strength was found to be higher for the films prepared at extreme pH region (pH 1, 2, 3, 11 and 12). The films formed gave high value of elongation at break owing to the presence of weaker bond which stabilized the film matrix. Higher pH of film-forming solutions with enhanced dispersion capacity in water favoured higher film solubility. The biodegradability of film showed the similar trend with film solubility. Nevertheless, pH of the film­ forming solutions had no impact on colour of the silver catfish mince films. All resulting films had excellent UV barrier properties at the wavelength of 200-280 nm regardless of pH of the film-forming solutions. These films also showed low light transmission at visible range (400-800 nm).