Fermentation characteristics and transit tolerance of probiotic Lactobacillus casei Zhang in soymilk and bovine milk during storage

Abstract

Lactobacillus casei Zhang is a novel strain that was screened out of koumiss collected in Inner Mongolia, and our previous research showed that L. casei Zhang has health benefits such as cholesterol-reducing and immunomodulating effects. The fermentation characteristics of L. casei Zhang in soymilk and bovine milk and the transit tolerance of L. casei Zhang in fermented milk products during refrigerated storage for 28 d were assessed. A faster decrease in pH and faster growth of L. casei Zhang during fermentation were observed in soymilk compared with bovine milk at various inoculation rates, probably because of the low pH buffering capacity of soymilk. The fermented bovine milk samples had much higher final titratable acidity (TA) values (between 0.80 and 0.93%) than the soymilk samples (between 0.40 and 0.46%). Dramatic increases in TA values in the fermented soymilk samples during storage were observed, and the TA values of the fermented soymilk samples changed from <0.56% to values between 0.86 and 0.98%. On the other hand, only slight increases in TA were observed in the bovine milk samples during the 28 d of storage. The survival rates of freshly prepared cultures of L. casei Zhang in simulated gastric juice at pH 2.0 and 2.5 were 31 and 69%, respectively, and the delivery of L. casei Zhang through fermented soymilk and bovine milk significantly improved the viability of L. casei Zhang in simulated gastric transit. Lactobacillus casei Zhang showed good tolerance to simulated gastric juice and intestinal juice in the fermented soymilk and bovine milk samples, and maintained high viability (>10(8) cfu/g) during storage at 4 degrees C for 28 d. Our results indicated that both soymilk and bovine milk could serve as vehicles for delivery of probiotic L. casei Zhang, and further research is needed to elucidate the mechanism of the change in pH and TA of L. casei Zhang in fermented milk samples during fermentation and storage and to understand the difference between soy- and milk-based systems.

Evaluation of probiotic potential of lactic acid bacteria isolated from traditional Malaysian fermentedBambangan(Mangifera pajang)

“…This shows that either trypsin or an alkaline condition at pH 8.0 does not significantly affect the viability of the Lactobacillus probiotic candidates. A similar result was also reported by Wang et al (2009) that approximately 97% of Lactobacillus casei Zhang remained viable after being exposed to the intestinal juice for 4 hours. Interestingly, comparison between the viability of probiotic candidates in the simulated gastric juice at pH 2.0 with and without the addition of enzymes (Figure 1c) shows that the viability of most Lactobacillus strains increased by 1-4 log CFU/ml with the addition of pepsin.…”

Performances of new isolates of Bifidobacterium on fermentation of soymilk

“…The latter concept should be more attractive from all scientifi c, technical and nutritional points of view, because in one processing step there is possibility to remove off-fl avour effects causing by n-hexanal and pentanal (mainly occurring in beans and formed from unsaturated fatty acids) [9]; and production of probiotic products with high nutritional values. In the last few decades, intensive research dealing with fermentation of soymilk using mainly Lactobacillus and Bifi dobacterium strains was carried out worldwide [10][11][12][13][14]. Hydrolysis of isofl avones as well as production of fl avourful lactic acid during fermentation of soymilk was reported by Bordignon et al in 2004 [15].…”

Survival of Lactobacillus rhamnosus GG during Simulated Gastrointestinal Conditions Depending on Food Matrix

“…In addition, soy milk has been reported to have protective buffering capacities as well -use of fermented soymilk as a delivery vehicle for probiotic Lactobacillus casei Zhang increased the tolerance to simulated gastric and intestinal juice (Wang et al, 2009).…”