DIFFERENT ARRANGEMENT OF ?-(?-GLUTAMYL)LYSINE CROSS-LINKING IN ALASKA POLLOCK (THERAGRA CHALCOGRAMMA) SURIMI PROTEINS BY STREPTOVERTICILLIUM AND ENDOGENOUS TRANSGLUTAMINASES DURING SUWARI PROCESS

Abstract

The objective of the present study is to compare the protein cross-linking reaction in Alaska pollock surimi that is catalyzed by a commercially available microbial transglutaminase and by endogenous Alaska pollock transglutaminase The endogenous transglutaminase was inhibited by EGTA and activated by CaCl 2 . The microbial transglutaminase was added to the salted surimi with and without EGTA and CaCl 2 . These surimi pastes were incubated at 25C up to 24 h followed by cooking at 90C. The resultant gels were fractionated into soluble and insoluble (aggregate) fractions by SDS-urea extraction. Compositional analysis revealed that the aggregate consisted predominantly of cross-linked myosin heavy chain. The distribution of e-(γ-glutamyl)lysine isopeptide in the soluble and aggregate fractions andpeptide mapping analyses ofthe aggregate fraction demonstrate thatthe formation of isopeptide cross-links in Alaska pollock surimi proteins during suwari process differs when catalyzed by the microbial transglutaminase and endogenous transglutaminase. La pâte de surimi peut gelifier a faible temperature (20-40°C) sans procede de cuisson. L'objectif de cette etude est de comparer la reticulation des proteines, pendant le procede de gelification dans du surimi de Theragra chalcogramma, par une transglutaminase commerciale microbienne (Streptoverticillium) et par une transglutaminase endogene. Les pâtes de surimi sont incubees a 25°C pendant 24h puis cuites a 90°C. Les gels produits sont separes en fractions solubles et insolubles et analyses.