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Research is presented concerning the molecular changes which result from the action of transglutaminase in foods. The comparison of proteins extracted from croissant and bread dough treated with transglutaminase and proteins not treated is discussed.

A study was conducted to examine the influence of using transglutaminase on effects related to oxidizing improvers and intensive mixing in breadmaking. Three standard doughs were utilized as experimental controls while a miniature extensigraph method was used to carry out dough strength measurements. Results indicated that transglutaminase minimized work input and enhanced the water absorption of dough.

Research into pastry and croissants containing transglutaminase.

Byline: M. Garvey, S.L. Gras, S. Meehan, S.J. Meade, J.A. Carver, J.A. Gerrard Self assembling protein nanofibres have great potential within the nanotechnology industry. To realise this potential, nanofibres need to be manufactured on a commercial scale. To date, amyloid fibrils, a form of protein nanofibre with desirable bionanotechnological properties, have only been produced using expensive and time-costly, small-scale methods. This paper describes the production of protein nanofibres from semi-pure and crude mixtures of bovine crystallin proteins, currently a waste product in the meat industry. These nanofibres displayed amyloid fibril characteristics. Moreover, distinct fibre morphologies were observed dependent upon the formation conditions adopted. This research shows that amyloid fibrils can be inexpensively produced from crude crystallin protein mixtures, making them a potential industrial source for protein nanofibres.

Abstract: In this paper, we explore the use of Maillard cross-linking agents (formaldehyde, glyceraldehyde and glutaraldehyde) in tofu, to probe the relationship between cross-linking of soy proteins and tofu texture. 1–2mM glutaraldehyde treatment resulted in an acceptable product with altered microstructure. At 2mM glutaraldehyde, the fracture force was increased if the reagent was added before soymilk boiling, but decreased if it was added after boiling, when more cross-linking was observed due to the denaturation of the proteins. The fracture forces and microstructures are hard to rationalise in terms of cross-linking, suggesting that other factors, such as non-cross-linking protein glycation, may be responsible for the observed changes. Taken together with the results reported in the previous paper, these findings suggest that protein cross-linking agents may change the functional properties of tofu via non-cross-linking modifications of the sidechains of the amino acid residues, changing their isoelectric point and their gelation properties. [Copyright &y& Elsevier]

Abstract: The enzyme transglutaminase was investigated for its cross-linking effect on the soy proteins of tofu. In vitro incubations confirmed that soy proteins are excellent substrates for transglutaminase, especially when denatured. The macroscopic effects resulting from the addition of transglutaminase were compared to changes at the microstructural and molecular level. Treatment produced a firmer tofu, with a significantly increased fracture force. Examination by SEM showed a change in the matrix structure, with transglutaminase resulting in a finer-stranded, uniform network that accounted for the increase in fracture force. At the molecular level, little, if any, cross-linking occurred within the tofu matrix in situ. This suggests that the change in functional properties afforded by addition of transglutaminase to tofu is due to a side reaction of the enzyme, for example hydrolysis of glutamine residues, rather than its cross-linking activity. These ideas are further explored in the accompanying paper. [Copyright &y& Elsevier]