Project
UHT milk
The effects of plasmin and psychrotrophic bacterial proteases on the physico-
chemical properties of UHT milk.
Introduction
Age gelation in UHT milk is an irreversible condition, described as coagulation, sweet curd formation, thixotropic thickening, or lumpiness after the product has been stored for weeks to months. These phenomena are related to the physico-chemical properties closely. In bulk milk with high bacterial counts and high somatic cell count (SCC), the impairment of product quality is intensified (Barbano et al., 2006).
A typical visual distinction appears due to the effects of the two types of protease is that, in stored UHT milk, bacterial proteases lead to the formation of a curd or a gel with tighter protein networks with thicker strands and contains more intact casein micelles and micelle aggregates than plasmin-initiated gels. Plasmin-treated milks have been shown to contain partially disintegrated casein micelles and linkages (Datta and Deeth, 2003).
Systematic measurement and comparison of the effects of plasmin and psychrotrophic bacterial proteases on the physico-chemical properties of UHT milk can contribute much to the detection and prediction of age gelation in practise.
Aim
• What are the effects of plasmin and psychrotrophic bacterial proteases on the physico-chemical properties of UHT milk?
Age gelation in UHT milk is an irreversible condition, described as coagulation, sweet curd formation, thixotropic thickening, or lumpiness after the product has been stored for weeks to months. These phenomena are related to the physico-chemical properties closely. In bulk milk with high bacterial counts and high somatic cell count (SCC), the impairment of product quality is intensified (Barbano et al., 2006).
A typical visual distinction appears due to the effects of the two types of protease is that, in stored UHT milk, bacterial proteases lead to the formation of a curd or a gel with tighter protein networks with thicker strands and contains more intact casein micelles and micelle aggregates than plasmin-initiated gels. Plasmin-treated milks have been shown to contain partially disintegrated casein micelles and linkages (Datta and Deeth, 2003).
Systematic measurement and comparison of the effects of plasmin and psychrotrophic bacterial proteases on the physico-chemical properties of UHT milk can contribute much to the detection and prediction of age gelation in practise.
Aim
• What are the effects of plasmin and psychrotrophic bacterial proteases on the physico-chemical properties of UHT milk?