Advances in dairy Research
Open Access
ISSN: 2329-888X
ISSN: 2329-888X
Dumpler Joseph
Technical University of Munich, Germany
Posters & Accepted Abstracts: J Adv Dairy Res
Heat stability of concentrated milk, i.e. the ability of milk protein to withstand severe heat treatments has been an issue since the beginning of industrial milk processing. Methods measuring heat coagulation time (HCT) as the usual parameter have limited relevance for industrial UHT processes with very short holding times at high temperature. However, there is a strong interest in long-term preservation of milk concentrates of high total solids content by heat treatment. This would give the opportunity to be able to avoid high energy consumption for spray drying of milk concentrates. In this study, a new lab-scale indirect heating method was established to describe heat stability of milk concentrates by measuring time and temperature within the sample until visual flocculation occurred. It appeard that visually detectable flocculation of concentrated milk samples of various total solids is strongly dependent on heating time and temperature in combination as well as total solids. Thus, the underlying mechanism of flocculation can be kinetically described. Another lab-scale technique was used to follow coagulation of the concentrated skim milk samples by particle sizing and separation techniques of the aggregates of casein micelles formed during heat treatment for a reaction kinetic approach towards heat-induced coagulation of preheated and non-preheated milk. We also found that a kinetic description of heatinduced aggregation of caseins also applies for direct steam injection heat treatment with some limitations. It was proven that direct heat-treatment is likely to be the method of choice for milk concentrate heat treatment for a long shelf life.
Email: joseph.dumpler@tum.de