Effect of microbial transglutaminase on rheological properties of oxidised and non-oxidised natural actomyosin from two species of bigeye snapper

The contribution of microbial transglutaminase (MTGase) to the thermal gelation of non-oxidised and oxidised natural actomyosin (NAM) from two species of bigeye snapper was studied by dynamic rheological testing. Under two-step heating, the addition of MTGase increased the gel-forming ability of both species. During setting at 40degreesC, Priacanthus macracanthus NAM seemed to show higher reactivity to MTGase than P tayenus NAM, resulting in a higher rate and magnitude of G' development. An increase in final G' of NAM from P macracanthus and P tayenus by 13.7-24 and 6.6-10.8 times respectively was observed compared with NAM alone. Iron-catalysed oxidation substantially decreased the gel-forming ability of P tayenus NAM but enhanced that of P macracanthus NAM. However, oxidation decreased the reactivity of both NAM types to added MTGase. The results suggested that the native NAM structure was essential for MTGase to maximise the setting response. The gel-forming ability and setting response of denatured NAM were partially recovered by the addition of MTGase. (C) 2002 Society of Chemical Industry.