The ability of Schisandra chinensis fruit to inhibit the growth of foodborne pathogenic bacteria and the viability and heat resistance of Bacillus cereus spores

The objective of this study was to investigate the influence of Schisandra chinensis fruit on the growth of spoilage and pathogenic bacteria and on the viability and heat resistance of Bacillus cereus spores. Schisandra chinensis fruit was extracted with one of three different solvents (50% ethanol, 100% ethanol and distilled water), and the extracts exhibited antimicrobial activity against all the bacteria tested. Particularly, the ethanol extracts of S. chinensis fruit had the strongest activity, in a concentration‐dependent manner. Fractionation of extracts by ion chromatography revealed that the antimicrobial activity of S. chinensis fruit is mainly due to organic acids such as citric acid and malic acid. Meanwhile, S. chinensis fruit extract (10%) significantly reduced the viability and heat resistance of B. cereus spores. Therefore, this study suggests that S. chinensis fruit extract has potential as a natural food preservative and/or sanitising agent for the reduction of spoilage and pathogenic contamination.     

Investigation of the ability of dairy nonstarter lactic acid bacteria to grow using cell lysates of other lactic acid bacteria as the exclusive source of nutrients

A new device named a cell sonicated substrate membrane system (CSSMS), consisting of a tissue culture insert that supplies nutrients, in the form of starter lactic acid bacteria (SLAB) lysate extract, through a polycarbonate membrane which isolates it from the nonstarter lactic acid bacteria (NSLAB) inoculum and serves as a support for bacterial growth, was developed. The CSSMS was used to demonstrate that the Lactobacillus helveticus SLAB lysate provides sufficient nutrients to allow the growth of L. casei and L. rhamnosus NSLAB in vitro. The results support the hypothesis that NSLAB could grow in aged cheese using only SLAB cell lysate as nutrients.     

Effect of mannoproteins on the growth, gastrointestinal viability, and adherence to Caco-2 cells of lactic acid bacteria

Yeast cell wall (YCW) preparations and yeast mannoprotein extracts have been effective against some enteropathogenic bacteria as Campylobacter jejuni, Escherichia coli, and Salmonella, and they can affect the population of beneficial lactic acid bacteria (LAB). In this work, we studied the effect of a mannoprotein extract on five strains of LAB. This extract was metabolised by the bacteria, enhancing their survival in simulated gastrointestinal juice, and increasing the adherence of Lactobacillus plantarum, L. salivarius, and Enterococcus faecium to Caco-2 cells. Yeast mannoproteins are promising naturally occurring compounds that could be used to enhance LAB intestinal populations and control pathogens.     

乳酸菌发酵提高麦胚可溶性蛋白和总酚含量及抑制脂质体氧化能力的研究

以可溶性蛋白及总酚含量为指标,在单因素实验基础上,采用正交实验设计优化乳酸菌发酵麦胚的条件,并考察了发酵产物在脂质体体系下的抗氧化能力。结果表明,起始p H影响显著,可溶性蛋白和总酚累积的最适发酵条件分别为p H5.0、VB6浓度150μmol/L、发酵时间12 h、发酵温度35℃及p H5.0、VB6浓度100μmol/L、发酵时间36 h、发酵温度35℃。在优化条件下,麦胚发酵产物水溶性组分中蛋白及总酚含量分别为24.86 mg/m L和0.876 mg/m L,比原料提高了1.74和1.45倍。同时,乳酸菌发酵提高了麦胚水溶性组分抑制脂质体氧化的能力,其脂质体氧化抑制率可达45.5%。通过对·OH清除及对Fe²⁺螯合能力的实验表明,麦胚发酵产物抑制脂质体氧化的能力与其羟基自由基清除能力有关。