Coagulation and washing conditions for acid casein production from skim milk powder

Abstract

SummaryResponse surface methodology was used to study the production of acid casein from skim milk powder and to investigate the effects of pH, concentration and washing conditions (agitation, time, temperature and wash water ratio) on the end product. The washed curd was analysed for residual ash, minerals and lactose. The critical variables were found to be concentration and pH in relation to mineral content; and concentration and washing time for lactose. Surface response methodology provides a unique insight into the relationships between the variables related to the process and the results are used to explain the observations in terms of milk chemistry. The washing process was further evaluated in terms of the Murphree Stage Efficiency to elucidate the effect of the number of washing stages on residual whey components in the casein curd. This study contributes to understanding the extrusion process of skim milk powder which makes use of higher milk solids concentrations.