NEW POSTER: Tyrosinase-induced crosslinking of milk proteins

Wednesday, 29 October 2008 17:00

Ercili Cura et al. investigated the effects of a novel tyrosinase from Trichoderma reesei in structure modification of chemically acidified sodium caseinate and skim milk gels. Enzyme-aided structure engineering of dairy products has taken much interest since the introduction of transglutaminase (TG), a transferase capable of forming inter- or intramolecular isopeptide bonds in protein systems. TG-aided crosslinking of caseins has been reported to lead to milk protein gels with increased firmness and less syneresis. Tyrosinase is an interesting alternative to TG, due to its different mode of action. In the presence of oxygen, tyrosinase is capable of oxidizing tyrosine residues in protein molecules, resulting in the formation of protein-protein crosslinking.

In this work, the action of T. reesei tyrosinase was compared with the action of the commercially available mushroom tyrosinase and TG. The novel tyrosinase produced from T. reesei induced crosslinking of caseins in raw milk, while mushroom tyrosinase and TG were ineffective. T. reesei tyrosinase treatment of raw milk prior to acidification resulted in increased gel stiffness. As the crosslinking ability of T. reesei tyrosinase, unlike that of TG, does not necessitate the pre-heating of milk, this enzyme can be exploited in texture engineering of milk products in which excessive heating of the milk is undesirable.

Reference: Ercili Cura, D., Lille, M., Buchert, J.. Lantto, R. Tyrosinase-induced cross-linking of milk proteins: Effects on the texture of chemically acidified sodium caseinate and milk gels, COST 928 Workshop, Istanbul 15 - 17 October, 2008.

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