The peptides in oat and malt extracts that are preferentially absorbed by Lactobacillus plantarum and stimulates its proliferation in milk

Abstract

SummaryLactobacillus plantarum proliferates inefficiently in milk, mainly because of its lack of cell envelope proteases and its inability to hydrolyse proteins in milk. Our previous study showed that this strain could grow well in milk with the addition of oat and malt extracts. To investigate the usage and preference for polypeptides and oligopeptides for this strain, sodium dodecyl sulphate‐polyacrylamide gel electrophoresis (SDS‐PAGE), o‐phthaldialdehyde (OPA), high‐performance liquid chromatography (HPLC), plate counting and other methods were used in this study. The results showed that proteins in fermented milk cannot be absorbed and utilised by L. plantarum, whereas polypeptides and oligopeptides provide available nitrogen sources for their growth. Short‐chain peptides were more conducive to absorption and utilisation than long‐chain peptides. In particular, peptides with molecular weights in the range of 200–1400 Da in the oat extract and 100–700 Da in the malt extract were preferentially absorbed and utilised.