Effects of pH on the properties of film from cobia (Rachycentron canadum) myofibrillar muscle

Abstract

The objective of this study was to determine the effect of pH of the film-forming solutions on the properties of film made from cobia myofibrillar muscle. Films from cobia (Rachycentron canadum) myofibrillar muscle were obtained by casting technique. The films have been successfully formed at pH of the film-forming solutions 3, 4, 7, 11 and 12. The thickness of cobia myofibrillar muscle films produced at different pH of film-forming solutions varied slightly. However, the thickness of the films was quite low. In terms of mechanical properties, different pH of the film-forming solutions affected the tensile strength of the cobia myofibrillar muscle films. The highest tensile strength was made at extreme alkaline pH (pH 12) while the lowest tensile strength was made at neutral pH (pH 7). Acidic and alkaline pHs improved the tensile strength of cobia myofibrillar muscle film. However, on the other hand, no significant effect of pH of the film-forming solutions was observed on elongation at break (EAB %) of the cobia myofibrillar muscle films. Water vapor permeability (WVP) also was not affected by pH of the film-forming solutions. The films become darker as the pH of film-forming solutions increased as evidenced by the increase in L * -value. Increase pHs have increased UV and visible light barrier properties. The highest film solubility was given at pH 12. Some pores were evident for film prepared at pH 3 due to the presence of bubble during film preparation. The distribution of fat structures also was detected in the microstructure of films due to ineffective washing process.