Laboratory of Food Biochemistry, Graduate School of Fisheries Sciences, Hokkaido University, Hakodate 041-8611, Japan
Carp actomyosin sol containing 90mg protein/g in 0.5M NaCl (or 1M NaCl) at pH 7.0 was heated from 5 to 80°C at heating rate of 2°C/min. The non-proteolytic modori (gel weakening) which occurred characteristically during actomyosin gelation was detected at 53°C by measuring storage modulus (G′) of the sol. The addition of ethanol and n-butanol to the sol did not suppress the non-proteolytic modori but shifted the modori temperature to 51°C and 42°C, respectively. Butanol greatly increased the G′ and the breaking strength of actomyosin gel formed.
The addition of pyrophosphate-Mg (PPi-Mg) dissociated actin and myosin from actomyosin, and changed the thermal gelation pattern of actomyosin sol to a myosin-like one. The change eliminated non-proteolytic modori, though PPi-Mg did not increase the G′ or the breaking strength of thermally induced gel. PPi-Mg made no contribution to a great increase in the gel strength of actomyosin gel formed by a two step heating method including microbial transglutaminase-induced setting.