Variation in milk composition and its correlation to rennet induced coagulation : a case study from northern Sweden

Sammanfattning: The coagulation of milk is a basic requirement in cheese making and determines yield, texture and aromas. The coagulation time and the resulting gel is due to the milk properties, variation and quality. As the industry strives to optimize production and have a consistent quality of cheese, it is of utter importance to know the factors influencing on coagulation properties. The aim of the study was to evaluate variation of milk composition and properties of farm milk from northern Sweden to determine correlations with rennet induced coagulation. Fat, protein, pH, casein micelle size (CMS) and milk fat globule (MFG) size of the raw milk was recorded. Gel strength (G20) and rennet coagulation time (RCT) was studied. Farm milk was divided into three different pooled silos based on farm factors. The study showed increased CMS from November to September as well as an increase in coagulation time and decrease in gel firmness and pH. A principal component analysis showed a positive correlation between CMS and G20 in the trial in November, contradicting to the literature. Thus, the result show correlations between milk composition and coagulation properties. However, no clear patterns can be observed from the study but need further research where a broader perspective and factors should be considered.