title: Comparative study on protein cross-linking and gel enhancing effect of microbial transglutaminase on surimi from different fish.
abstract: BACKGROUND
  Microbial transglutaminase (MTGase) has been used to increase the gel strength of surimi. Nevertheless, its effectiveness varies with fish species. The aim of this study was to elucidate the effect of MTGase at different levels on protein cross-linking and gel property of surimi from threadfin bream, Indian mackerel and sardine in the presence and absence of endogenous transglutaminase.
  
  
  RESULTS
  Breaking force of all surimi gels increased as MTGase levels (0-0.6 U g⁻¹) increased except for threadfin bream surimi gel, where the breaking force decreased at 0.6 U g⁻¹ (P < 0.05). In the presence of EDTA, the gel strengthening effect was lower, suggesting the combined effect of endogenous transglutaminase with MTGase. With the addition of MTGase, the gel with the highest increase in breaking force showed highest decrease in myosin heavy chain. When cross-linking activity of MTGase on natural actomyosin (NAM) was determined, the highest decreasing rate in ε-amino group content with the concomitant increased formation of cross-linked proteins was found in NAM from threadfin bream. The reactivity of muscle proteins toward MTGase-induced cross-linking was in agreement with surimi gel strengthening.
  
  
  CONCLUSIONS
  The composition and properties of muscle proteins of varying fish species more likely determined protein cross-linking induced by MTGase, thereby affecting their gel properties.
authors.affiliation: Department of Food Technology, Faculty of Agro-Industry, Prince of Songkla University, Hat Yai, Songkhla, Thailand.
authors.forename: Sochaya
authors.initials: S
authors.lastname: Chanarat
authors.forename: Soottawat
authors.initials: S
authors.lastname: Benjakul
authors.forename: Aran
authors.initials: A
authors.lastname: H-Kittikun
mesh_terms: D000205:Actomyosin / Q000737:chemistry / Q000378:metabolism; D000818:Animals; D001426:Bacterial Proteins / Q000302:isolation & purification / Q000378:metabolism*; D002118:Calcium / Q000737:chemistry; D002614:Chelating Agents / Q000737:chemistry; D055598:Chemical Phenomena; D003116:Color; D004492:Edetic Acid / Q000737:chemistry; D005396:Fish Products / Q000032:analysis*; D029941:Fish Proteins / Q000737:chemistry* / Q000378:metabolism*; D005511:Food Handling; D005782:Gels; D055595:Mechanical Phenomena; D018995:Myosin Heavy Chains / Q000737:chemistry / Q000378:metabolism; D010473:Perciformes / Q000378:metabolism; D021541:Sea Bream / Q000378:metabolism; D013302:Streptomyces / Q000201:enzymology; D013997:Time Factors; D011503:Transglutaminases / Q000302:isolation & purification / Q000378:metabolism*; D014867:Water / Q000032:analysis
chemical_list: D001426:Bacterial Proteins; D002614:Chelating Agents; D029941:Fish Proteins; D005782:Gels; D014867:Water; D000205:Actomyosin; D004492:Edetic Acid; D011503:Transglutaminases; D018995:Myosin Heavy Chains; D002118:Calcium