The physicochemical properties and heat stability of milk fortified with blackberry juice and different casein-dominant ingredients

The influence of blackberry juice (BBJ) on the physicochemical properties and heat stability of skimmed milk with and without sodium caseinate or micellar casein concentrate (MCC) addition was investigated. This was performed by measuring the ionic calcium content, heat coagulation time, viscosity, particle size distribution and analytical centrifugation profiles of the different samples. BBJ decreased the ionic calcium of the samples, which resulted in a higher heat coagulation time at pH < 6.5. Its addition also prevented the increase in viscosity observed in skimmed milk and skimmed milk with MCC at pH 6.2 after heating. The particle size distribution, turbidity and analytical centrifugation profiles indicated this was due to a prevention of protein aggregation. In conclusion, the blackberry juice improved the heat stability of different types of milk systems in the pH range between 6.2 and 6.4, which was likely due to binding of calcium by blackberry polyphenols.