Effect of ethanol on physico-chemical properties of micellar casein concentrate.

Abstract

Casein (CN) is major milk protein which exists in milk in form of micelles of size ranging from 50 to 500nm. The CN micelles were harvested using microfiltration (MF) with 0.1 μm membrane in their native state. The CN micelles harvested using MF are called micellar CN concentrate (MCC). MCC harvested was treated by ethanol at rate varying from 10 to 40 % and strength varying from 10 to 80%. This treatment caused disintegration as well as aggregation. More pronounced results were observed in case of 60 – 80 % alcohol strengths added at rate of 40 %. Aggregated network of CN micelles was distinct in the transmission electron micrograph. The magnitude of Zeta potential decreased towards negative side in this treatment as aggregation occurred. The zeta potential varied from -16.2 mV to -8.2 mV in case of buffalo MCC when it was treated with 20 to 80 % alcohol strength at the rate of 40%. This value varied from -17 mV to -10 mV in case of cow MCC. PSD of skim milk showed that aggregation was observed at higher strengths only and disintegration was seen to a very less extent. In case of MCC disintegration was seen at 60 – 80 % alcohol strengths and aggregation was evident at 40 to 80 % (maximum at 80 %). This study would be helpful in manipulating physicochemical properties of CN micelles in different food systems.