The F1F0-ATPase β-subunit mutation strain L. plantarum LPM21 was screened to resolve the post-acidification of Sichuan pickle products caused by the probiotic adjunct cultures L. plantarum during product handling, transportation or storage at ambient temperature. Ser-268 mutation into Leu-268 in F1F0-ATPase β-subunit of LPM21, located in the interaction interface of F1F0-ATPase α- and β-subunit, triggered a 43.44% drop in the ATPase activity. In MRS broth, LPM21 could not grow under desired pH 4.2 and its acid production was about 1/2 of parent L. plantarum CCTCC 207202. When LPM21 cultures were incorporated into aseptic Sichuan pickle products, the pH of products was 4.3 after 7 d incubation at 30°C, above the critical pH limit of 4.2. Furthermore, LPM21 viable count with 7.27 log CFU mL−1 satisfied the criteria for a probiotic food product. Therefore, L. plantarum LPM21 as probiotic adjunct has the potential for reducing the post-acidification of probiotic Sichuan pickle.
2013 by Japanese Society for Food Science and Technology