Abstract:

 This study has explored the effects of different starter cultures including three strains of lactic acid bacteria
and their combinations on the peptide changes of fermented yak meat sausage. Lactobacillus sake (L. s), Lactobacillus
plantarum (L. p), Pediococcus pentosaceus (P. p) and their combination were artificially inoculated for the fermentation
of yak meat sausage. pH values were determined at intervals of 24 hours. Samples were collected after 2 days of primary
fermentation (32 ℃) and after 10, 20, and 30 days of natural air-dry fermentation. Peptide content of yak meat sausages was
analyzed by reversed phase high performance liquid chromatography (RP-HPLC). The results showed that all different lactic
acid bacteria and their combinations except P. p and L. p + P. p had significant effects on the peptide contents of yak meat
sausage after 2 days of primary fermentation and after 10, 20, and 30 days of natural air dry fermentation (P < 0.05). The
highest peptide contents of 1.73 × 105, 1.62 × 105, 1.81 × 105 and 1.83 × 105 mAU·s in yak meat sausages fermented with L. s,
P. p, control (no starter culture) and L. p, respectively, were detected at the above four fermentation times sequentially. With
the extension of fermentation time, notable changes were observed in the peptide content of fermented yak meat sausage.
The content of peptides with relatively weak polarity was reduced, whereas peptides with relatively strong polarity largely
remained unchanged. At the end of primary fermentation, the L.s group showed the maximum total peptide content, and the
changes in the total peptide contents of the L. s, L. s+P. p, L. s + L. p + P. p groups presented similar trends. L. s fermentation
was able to quickly generate peptides in yak meat sausage. At the four fermentation periods, the peptide content of the
L. p+L. s group were lower than that of the single strain groups, and L. p + L. s even showed inhibition on the production of
peptides in yak meat sausage. L. s and P. p demonstrated no observable differences in peptide production, but could quickly
reduce the pH value, ensuring the safety of the product. These results may provide useful information for the commercial
production of yak meat sausage with high quality.

Key words: lactic acid bacteria, fermentation, yak meat sausage, peptides, reversed phase high performance liquid chromatography (RP-HPLC)