Influence of heat treatment and calcium sequestering salts on in vitro protein digestion in blends of skimmed buffalo and bovine milk

Abstract

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.