Properties of casein micelles cross-linked by transglutaminase |
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Authors: | JEONG-HAN MOON,YOUN-HO HONG,THOM HUPPERTZ &dagger ,PATRICK F FOX, ALAN L KELLY |
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Affiliation: | Department of Food and Nutrition, College of Human Ecology, Chonnam National University, Gwangju, South Korea,;Department of Food and Nutritional Sciences, University College Cork, Cork, Ireland |
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Abstract: | Factors affecting the cross-linking of milk proteins by transglutaminase (TGase) were studied. Cross-linking of caseins in bovine skim milk was optimal over a very wide pH range. The role of micellar calcium phosphate (MCP) in maintaining the integrity of TGase-treated casein micelles was studied by incubating skim milk with 0.01% (w/v) TGase at 30°C for 1–24 h, followed by removal of MCP from untreated or TGase-treated milk by acidification and dialysis. The protein content and profile of the samples were determined by Kjeldahl and SDS-PAGE, respectively. Whey proteins in unheated milk were not susceptible to TGase-induced cross-linking. The higher level of sedimentable protein in MCP-free TGase-treated milk than in MCP-free control milk indicated that TGase treatment partially prevented disintegration of the micelle on removal of MCP, probably due to extensive intramicellar TGase-induced cross-linking of casein molecules which led to the formation of sedimentable covalently bonded casein aggregates. |
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Keywords: | Milk Casein micelle Transglutaminase Calcium phosphate |
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