The effect of the chemical structure of CMC on the stability of milk protein

In this paper, two types of carboxymethyl cellulose samples CMC_m and CMC_e, used for foodstuffs stability, were prepared in mixed isopropanol and ethanol system at high bath ratio and in ethanol system at low bath ratio, respectively. The stability of two types of carboxymethyl cellulose milk micelle was analyzed by their acid salt tolerance property of these milk beverages. The results showed that the CMC_m milk beverage showed higher ratio of acidity to viscosity (AVR), higher temperature resistance, lower precipitation ratio(AVR)and better stability. The morphology structure of milk protein was studied by SEM. It showed that the structure of milk protein with CMC_m formed continuous network and homogeneous morphology. However the structure of milk protein with CMC_e showed network defects and tendency of aggregation. In order to have in-depth discussion on the structure-property relationship, the distribution of carboxymethyl group on CMC_m and CMC_e was researched by NMR. The CH₂COO^- group on anhydroglucose unit (AGU) of CMC_m showed regioselectively substituted at C₆, while CMC_e had high selectively substituted at C₂.