Abstract:

The incubation conditions of LaetobaciUus rhamnosus 6013 in MRS broth were investigated and the stability of the strain in the pmcessing of soy cheese was evaluated.An anaerobical incubation at 37 ℃ for 48 h was then determined as the optimal condition for the culture of the strain.in which excellent inhibitory efect of the culture supernatant on Staphylococcus aureus,Bacillus cereus and Salmonella typhimurium was revealed.Then,a bacterium-fermented soy cheese was prepared from soy milk treated with bacterial starter cultures(DH₁,GH₄)and L.rhamnosus 6013.It is found that the viable count of the strain reaches 10⁸ ~10⁹ CFU/mL after ferm entati0n for 6h,that the pH value slightly decreases and the viable count achieves 10⁷ CFU/g after storage at 10℃for 30 days, while the viable counts of DH l and GH4 are all 10⁶CFU/g, and that,when the NaCl content of brine is 20.00~40.oo g/L，little efect of L．rhamnosus 6013 on the survivability is observed．A1l these indicate that the potential probiotic strain L．rhamnosus 6013 can withstand the processing of soy cheese and has no negative effect on the ferm entation of soy cheese．

Key words: Lactobacillus rhamnosus , soy cheese, inhibitory effect, ferm entation, survivability, stability