The aim of this work was to test the diffusion-controlled hypothesis of milk coagulation kinetics by reducing the diffusion coefficient of casein micelles. This has been achieved by increasing the solvent viscosity of milk through sucrose addition. Milk was reconstituted from skim milk powder and sucrose added at 100-300 g kg-1. Hydrolysis and coagulation were followed by chromatographic determination of caseinomacropeptide content and optical, thermal and viscoelastic measurements. Soluble and ionic calcium were determined by atomic absorption spectrophotometry and ionometry and micelle size was measured by dynamic light scattering. Addition of sucrose resulted in a substantial retardation of both enzymic and aggregation steps, a re-equilibration of calcium because of water reduction, and a micelle size increase. The enzymic rate constant was inversely proportional to the viscosity, according to a diffusion-controlled model, and the lag or characteristic times for the aggregation reaction were inversely proportional to the viscosity. These results are consistent with the involvement of diffusion-controlled steps in the sequence of reactions.
显示更多 [+] 显示较少 [-]
AGRIS - 国际农业科技情报系统
Share
出版者
Blackwell Publishing Ltd
其它主题
Micelles
语言
英语
类型
Journal Article; Text
2024-02-27
2026-02-03
MODS