Abstract:

Pure milk samples with separately added phytic acid and phenolic compounds such as ferulic acid, tannin, salicylic acid and p-hydroxybenzoic acid at different levels were subjected to standing at normal temperature for 1 h or sterilization at 121 ℃ for 20 min followed by cooling to the normal temperature prior to pepsin hydrolysis in order to investigate the effects of phytic acid these phenolic compounds on the in vitro digestibility of milk proteins. The results indicated that all these compounds added alone resulted in a decrease in digestibility of milk proteins by 5%－27%. Prolonged length of standing time after cooling to the normal temperature (in the case of milk samples subjected to sterilization) resulted in a higher protein digestibility. Moreover, with increasing pepsin concentration, protein digestibility in vitro increase by 1%－9%.

Key words: phytic acid, phenolic acid, milk proteins, protein digestibility in vitro