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This study investigated the effect of gum arabic (GA) combined with microbial transglutaminase (TG) on the functional properties of porcine myofibrillar protein (MP). As an indicator of functional property, heat-set gel and emulsion characteristics of MP treated with GA and/or TG were explored under varying NaCl concentrations (0.1-0.6 M). The GA improved thermal gelling ability of MP during thermal processing and after cooling, and concomitantly added TG assisted the formation of viscoelastic MP gel formation. Meanwhile, the addition of GA decreased cooking yield of MP gel at 0.6 M NaCl concentration, and the yield was further decreased by TG addition, mainly attributed by enhancement of protein-protein interactions. Emulsion characteristics indicated that GA had emulsifying ability and the addition of GA increased the emulsification activity index (EAI) of MP-stabilized emulsion. However, GA showed a negative effect on emulsion stability, particularly great drop in the emulsion stability index (ESI) was found in GA treatment at 0.6 M NaCl. Consequently, the results indicated that GA had a potential advantage to form a viscoelastic MP gel. For the practical aspect, the application of GA in meat processing had to be limited to the purposes of texture enhancer such as restructured products, but not low-salt products and emulsion-type meat products.

This study investigated the effects of microbial transglutaminase (MTGase) and pH-shift processing on the functional properties of porcine myofibrillar proteins (MP). The pH-shift processing was carried out by decreasing the pH of MP suspension to 3.0, followed by re-adjustment to pH 6.2. The native (CM) and pH-shifted MP (PM) was reacted with and without MTGase, and the gelling and emulsion characteristics were compared. To compare the pH-shifted MTGase-treated MP (PT), deamidation (DM) was conducted by reacting MTGase with MP at pH 3.0. Rigid thermal gel was produced by MTGase-treated native MP (CT) and PT. PM and DM showed the lowest storage modulus (G') at the end of thermal scanning. Both MTGase and pH-shifting produced harder MP gel, and the highest gel strength was obtained in PT. All treatments yielded lower than CM, and CT showed significantly higher yield than PM and DM treatments. For emulsion characteristics, pH-shifting improved the emulsifying ability of MP-stabilized emulsion, while the treatments had lower emulsion stability. PM-stabilized emulsion exhibited the lowest creaming stability among all treatments. The emulsion stability could be improved by the usage of MTGase. The results indicated that pH-shifting combined with MTGase had a potential application to modify or improve functional properties of MP in manufacturing of meat products.