Influence of pH, ionic strength and isoascorbic acid on the gel-forming ability of Jumbo squid muscle (Dosidicus gigas)

The effect of pH and ionic strength (mu) on the extraction capacity of myofibrillar proteins from Jumbo squid mantle muscle along with the addition of isoascorbic acid (IA) in its gel-forming ability (GFA) were evaluated. The results indicate that mu had a greater impact (p < 0.05) than pH on the extraction of muscle myofibrillar proteins. The effectiveness of IA, as the precursor of dehydro-isoascorbic acid (DIA), on the oxidation of sulfhydryl groups (-SH) to disulfide bonds (-S-S-) of extracted proteins at 0.6 mu was also evaluated. During the sol-gel transition the -SH groups initially present in the protein system decreased (p < 0.05) due to the combined effect of heat treatment (90 degrees C/30 min) and the addition of IA; however, the oxidative effect of IA reduced (p < 0.05) the GFA of Jumbo squid muscle proteins. Results also indicated that NaCl at 2.8% rather than at 2.5% during gel preparation significantly (p < 0.05) improves its GFA.