Ethanol-Dependent Heat-Induced Dissociation of Casein Micelles

Abstract

The dissociation of casein micelles when heated to approximately 65 degrees C in the presence of ethanol [1:1 mixture (v/v) of milk and 65% (w/w) aqueous ethanol] was investigated using L* values and transmission measurements. Mixtures of milk and ethanol became transparent on heating, which suggests dissociation of casein micelles. Results of experiments using confocal laser scanning microscopy, light scattering (static and dynamic), and dialysis to examine the changes of milk during heating in the presence of ethanol supported the assertion that such treatments result in dissociation of casein micelles, as did studies of model beta-casein micellar systems.

Effects of calcium chelating agents on the solubility of milk protein concentrate

“…Overall, there was good correlation between the decrease in L ‐value (Figure ) and the presence of casein fractions in the serum phase of centrifuged MPC dispersions (Figure ; lanes 3, 4, 7 and 8), indicating casein micelle dissociation, as described by O'Connell et al . () and Smiddy et al . ().…”

“…Particle size distributions of milk protein concentrate dispersions (50°C; 10%, w/w) hydrated alone (■) in water or in conjunction with 15, 75 or 150 mEq/L trisodium citrate (□), sodium phosphate (▲) or sodium hexametaphosphate (Δ).heat treatment of the commercial MPC powder. Overall, there was good correlation between the decrease in L-value(Figure 4) and the presence of casein fractions in the serum phase of centrifuged MPC dispersions (Figure 5; lanes 3, 4, 7 and 8), indicating casein micelle dissociation, as described byO'Connell et al (2001) andSmiddy et al (2006).…”

Structure and stability of nanogel particles prepared by internal cross-linking of casein micelles

“…All these three parameters do not change, so the Q-dependence is represented by the scattering form factor P(Q), which decays faster for a larger particle. Heating a native casein micelle dispersion in the presence of ethanol, leads to a disruption of the casein micelles as a result of increased solvent quality (O'Connell, Kelly, Auty, Fox, & de Kruif, 2001a;O'Connell, Kelly, Fox, & de Kruif, 2001b), which is now prevented by the enzymatic crosslinking. Based on the findings described above, micelles in which all caseins are cross-linked can be described as a covalently linked protein network from which MCP can be solubilised and which displays swelling behaviour on changes in solvent quality, leading to classification of them as casein nanogel particles .…”

Efeito da temperatura das amostras de leite na concentração de cálcio solúvel e de beta-caseína: interferência no teste de estabilidade frente ao etanol

“…Diversos estudos (Creamer et al, 1977;Ali et al, 1980;Davies e Law, 1983;O'Connell et al, 2001;Huppertz e De Kruif, 2007) mostraram que ocorrem variações nas propriedades físico-químicas do leite em função da temperatura, do pH e da concentração de sais. Entre as modificações que acontecem durante o processo de resfriamento do leite, estão incluídas a dissociação das caseínas, especificamente a β-caseína, solubilização do fosfato de cálcio coloidal e diminuição no tamanho das micelas (Walstra e Van Vliet, 1986;Horne, 2003).…”