Calcium in water buffalo (Bubalus bubalis) milk : implications for Mozzarella production

Abstract: Mozzarella is a popular fresh cheese that is traditionally made by hand from fresh buffalo milk, involving a finishing step of stretching the cheese curd in hot water. The ability of the curd to stretch in hot water is dependent on the amount of calcium removed from the curd during the reduction of pH in the milk. The distribution of calcium between colloidal and soluble phase can change dependent on what treatment the milk is submitted to, such as prolonged storage or acidification. The aim of this study was to investigate what effect prolonged storage of buffalo milk in combination with preacidification, would have on the concentration of calcium in whey and how this would affect the manufacturing of Mozzarella. The calcium content was analyzed according to IDF standard method (154:1992) and by using atomic absorption spectrophotometer. The chemical composition in milk was determined by using mid-infrared transmission spectrophotometer (Dma pump, Miris). Bulk buffalo milk was stored for 8 days and whey calcium and pH were measured daily. In addition, milk stored for 1, 4 and 8 days was inoculated with fresh starter culture for a maximum of 120 minutes, and calcium in whey and pH were measured after 15, 30, 60, 90 and 120 minutes. The chemical composition of individual and bulk milk samples from 7 water buffaloes was analyzed and found to be within the normal range, compared to previous studies. During prolonged storage at +4°C for 8 days the pH decreased from 6.82 to 6.5 and the soluble calcium in whey increased with 35%. The effect of preacidification on whey calcium was evaluated for milk subject to cold storage for 1, 4 and 8 days. Results showed that the calcium concentration in whey increased as pH decreased over 120 minutes. The present study found a strong correlation between pH, storage time and calcium in whey for milk subjected to prolonged storage and in addition, for milk that was preacidified with fresh starter culture for maximum 120 minutes. In conclusion, the present study shows that prolonged storage of milk in combination with preacidification affects the concentration of soluble calcium in whey, which could have implications for Mozzarella manufacturing.