Correlation between sensory properties and peptides derived from hydrolysed-lactose UHT milk during storage

The effects of storage conditions on the shelf-life of hydrolysed-lactose ultra-high-temperature (UHT) milk was evaluated using proteomics. Lactose content was initially reduced to approximately 40% by ultra- and nanofiltration before hydrolysis. Increased peptide and amino acid levels were observed in the milk over a seven-month storage period at room temperature. Potentially bitter peptides (Q-value > 1400 cal mol−1) increased in levels from 86 to 116 days of storage, which coincided with the shelf-life (three months) of this milk, as found by sensory analysis. Sensory descriptive analysis was used to describe the sensory characteristics of the milk during storage. Bitterness intensity significantly increased over time and was correlated with the level of peptides released via either enzymatic (proteolytic side activity of the enzyme used in lactose hydrolysis) or non-enzymatic pathways (heat and storage induction). This study reveals a relationship between proteolysis and decreased shelf-life of hydrolysed-lactose UHT milk compared with conventional UHT milk.