Influence of transglutaminase treatment on properties of micellar casein and products made therefrom

Abstract

-This work investigated the effect of transglutaminase on (1) micellar casein (phosphocasein) suspensions at pH 6.7; (2) gel formation at pH 4.6; and (3) viscosity of the subsequently produced sodium caseinates. Micellar casein (25 g protein·kg -1 in simulated milk ultrafiltrate, pH 6.7) was incubated with and without 1% microbial transglutaminase (Tgase) at 40°C for 5-60 min, prior to thermal inactivation (78°C × 30 min). The particle size of micellar casein incubated with Tgase (mean between treatments of 213 nm) was not markedly different from the control micellar casein (195 nm), indicating very little inter-micellar cross-linking. Heat stability was markedly improved at pH > 6.8 following incubation with Tgase. When Tgase was not inactivated prior to acidification gels were markedly stronger. The maximum in casein hydration (pH 5.2-5.5) and tan δ (pH 5.0) were eliminated by the action of Tgase indicating a loss of casein mobility. In the absence of Tgase, a sodium caseinate suspension had a low apparent viscosity of 7.6 mPa·s (100 s -1 ) with Newtonian behaviour, low turbidity (A 600nm = 0.28 and an ethanol stability of 530 mL·L -1 ). Sodium caseinate could not be produced where the Tgase was active during the acidification step. Sodium caseinate made from micellar casein treated with Tgase (5 min) showed increased viscosity (64.6 mPa·s at 100 s -1 ), turbidity (A 600nm = 1.37) and ethanol stability (621 mL·L -1 ). With the exertion of proper control, Tgase can improve some of the functional properties of micellar casein or its sodium caseinate derivative.high viscosity / sodium caseinate / transglutaminase / milk protein Résumé -Influence de la transglutaminase sur les propriétés de la caséine micellaire et de ses produits dérivés. L'effet de la transglutaminase sur (1) des suspensions de caséine micellaire (phosphocaséine) à pH 6,7; (2) la formation de gel à pH 4,6; et (3) la viscosité du caséinate de sodium obtenu par la suite, était étudié. La caséine micellaire (25 g protéine·kg -1 dans un ultrafiltrat de lait simulé, pH 6,7) était incubée en présence ou non de 1 % de transglutaminase (Tgase) d'origine microbienne à 40 °C pendant 5-60 min, avant inactivation thermique (78 °C × 30 min). La taille des particules de caséine micellaire incubée avec la Tgase (moyenne de 213 nm entre traitements) n'était pas considérablement différente de celle du contrôle de caséine micellaire (195 nm), indiquant de très faibles liaisons inter-micellaires. La stabilité thermique était considérablement améliorée à pH > 6,8 après incubation avec la Tgase. Quand la Tgase n'était pas inactivée avant acidification, les gels étaient considérablement plus forts. Les maxima d'hydratation de la caséine (pH 5,2-5,5) et tan δ (pH 5,0) étaient éliminés par l'action de la Tgase indiquant une perte de mobilité de la caséine. En absence de Tgase, une suspension de sodium de caséinate avait une faible viscosité apparente de 7,6 mPa·s (100 s -1 ) avec un comportement Newtonien, une faible turbité (A 600nm = 0,28) et une stabilité à...

Modifications of structures and functions of caseins: a scientific and technological challenge

“…With casein micelles, the rate of cross-linking was different and decreased in the following order: κ-casein>β-casein>α-casein (Sharma et al 2001;Smiddy et al 2006;Hinz et al 2007). By using dynamic light scattering, Mounsey et al (2005) and Moon et al (2009) found that the cross-linking induced by transglutaminase did not influence the micellar sizes suggesting intramicellar cross-linkings rather than intermicellar.…”

Effects of varying time/temperature-conditions of pre-heating and enzymatic cross-linking on techno-functional properties of reconstituted dairy ingredients

“…Post-incubative UHT-heating (90°C, 149 s + 138°C, 4.5 s), however, damaged viscosity-enhancing properties and resulted in comparable low apparent viscosity values of the reconstituted products. Mounsey et al (2005) also found that solutions of cross-linked sodium caseinate showed increased apparent viscosity, but they prepared the caseinate from transglutaminase-treated micellar casein. Nonaka et al (1992) studied gelation properties of cross-linked sodium caseinate but a comparison with the untreated product is missing.…”

“…They are not temperature dependent on heating and exhibit no syneresis even after long storage time (Schorsch, Carrie, Clark, & Norton, 2000a;Schorsch, Carrie, & Norton, 2000b). Mounsey, O'Kennedy, and Kelly (2005) found that the particle size of micellar casein incubated with transglutaminase (average 213 nm) was not markedly different from the control micellar casein (195 nm), indicating very little inter-micellar cross-linking. The critical protein concentration and temperature necessary to set off gelation of whey proteins are reduced with increasing enzymeinduced polymerization (Wilcox & Swaisgood, 2002).…”

“…Experiments with mixtures of native and polymerized b-casein also showed that increasing the fraction of polymerized b-casein in the mixture increased the emulsion stability (MingXia & Damodaran, 1999). A number of papers show that the heat stability of b-lactoglobulin (Tanimoto & Kinsella, 1988), whey protein isolate (Lorenzen, 2000), skim milk concentrate and powder (O'Sullivan et al, 2001;O'Sullivan, Kelly, & Fox, 2002) as well as micellar casein concentrate (Mounsey et al, 2005) was markedly enhanced by an transglutaminase treatment.…”

Current enzymatic milk fermentation procedures

“…Several studies examined the different supporting effects of enzymatic cross-linking of casein on gel-forming, heat stability, viscosity and micellar hydration [51][52][53][55][56][57][58]. For example, TGase-provoked mesh size reduction in the protein network with regular protein distribution increased gel strength, water-holding capacity and less syneresis in the yogurt gels [52,59].…”