Heat-induced interactions of calcium and protein in milk lead to undesirable changes in the milk, such as protein coagulation, which can be minimized through the addition of calcium-sequestering salts prior to heat treatment. Thus, the present study investigated the influence of 5 mM added trisodium citrate (TSC) or disodium hydrogen phosphate (DSHP) on the heat-induced (85 °C and 95 °C for 5 min) changes in physical, chemical, and structural properties of buffalo and bovine skim milk mixtures (0:100, 25:75, 50:50, 75:25, and 100:0). Significant changes in pH and calcium activity as a result of TSC or DSHP addition subsequently resulted in higher particle size and viscosity as well as non-sedimentable protein level. These changes are mostly observed during heat treatment at 95 °C and increased proportionally to the concentration of buffalo skim milk in the milk mixture. Significant changes were affected by TSC addition in the 75:25 buffalo:bovine milk blend and buffalo skim milk, but for other milk samples, TSC addition effected comparable changes with DSHP addition. Overall, the addition of TSC or DSHP before heat treatment of buffalo:bovine milk blends caused changes in milk properties that could reduce susceptibility of milk to coagulation.

This study investigated the impact of the addition of 5 mM trisodium citrate (TSC) or disodium hydrogen phosphate (DSHP) and heat treatment (85 or 95°C for 5 min) on the in vitro gastrointestinal digestibility of proteins in blends (0:100, 25:75, 50:50, 75:25, 100:0) of skimmed buffalo and bovine milk. Digestibility of proteins decreased with increasing proportion of buffalo skim milk, irrespective of heat treatment and calcium sequestering salt (CSS) addition. Heat treatment alone did not induce significant changes in the digestibility of proteins. CSS addition and heat treatment did not significantly affect whey protein digestibility but impacted the digestibility of κ-casein. While addition of TSC and DSHP induced comparable κ-casein digestibility in bovine skim milk and milk blends, the addition of TSC and heat treatment of buffalo skim milk effected maximum κ-casein gastrointestinal digestibility. Overall, α-lactalbumin and κ-casein were the most resistant proteins against degradation by digestive enzymes. These results may be useful in deciding appropriate process intervention that could maximise gastrointestinal digestion of proteins in buffalo and bovine milk blends.