Foodborne pathogens are serious challenges to food safety and public health worldwide. Fermentation is one of many methods that may be used to inactivate and control foodborne pathogens. Many studies have reported that lactic acid bacteria (LAB) can have significant antimicrobial effects. The current review mainly focuses on the antimicrobial activity of LAB, the mechanisms of this activity, competitive growth models, and application of LAB for inhibition of foodborne pathogens.
Lactococcus lactis QMF 11, isolated from Brazilian fresh cheese, produces bacteriocin like inhibitory substances (bac+). To evaluate L. lactis QMF11 possible application on biopreservation systems of dairy food, co‐inoculation studies were performed in pasteurized milk (8 °C, 10 days) targeting the inhibition of Listeria monocytogenes ATCC 7644 or Staphylococcus aureus ATCC 25923. Lactobacillus sakei ATCC 15521 was used as a negative control for bacteriocin production (bac−). L. monocytogenes and S. aureusreached 8 log CFU ml−1 and 5.4 log CFU ml−1 in monoculture, respectively, compared to <2.3 log CFU ml−1 and 4.7 log CFU ml−1 in co‐culture with L. lactis QMF 11. Instead, in the presence of the bac−, L. monocytogenes population reached 7.3 log CFU ml−1 and S. aureuspopulations 5.5 log CFU ml−1. These results indicate that L. lactis QMF11 may have potential for be use as biopreservative culture in dairy products, mainly because of its antilisterial activity.
There is a renewed interest in the use protective bacterial cultures or their metabolites to guarantee the microbiological safety and to extend the shelf life of dairy products, in a process called biopreservation. The research in this area has been leveraged by consumers demand for naturally preserved foods. Dairy products are natural niches for Lactococcus lactis strains, and these bacteria have been associated with food production and preservation since ancient times. As a dominant species in dairy ecosystems, L. lactisstrains are very interesting because they are not likely to require regulatory approval for practical application as bioprotective cultures.
In Tanzania, edible Ruspolia differens are still harvested from the natural environments. In this perspective, little is known about the microbiological quality of wild harvested R. differens. This study was conducted to assess the microbiological quality of wild harvested R. differens and evaluate the efficacy of conventional processing methods in reducing microbial load. Two districts (Bukoba rural and Muleba) within the Kagera region were purposively selected for the study. Sampling was done from the same batches along the R. differens food chain as follows: (a) at harvest points in the villages, (b) after transportation to the market and plucking of wings and legs, (c) after rinsing with potable tap water, and (d) after processing using conventional methods. Generally, high microbial counts, that is, total viable aerobic count (TVC), Enterobacteriaceae, lactic acid bacteria, bacterial endospores, and yeasts and molds were observed in raw R. differenssamples. A significant increase in microbial counts after transportation and plucking was only observed for TVC, bacterial endospores, and yeasts and molds. A statistically significant reduction in all types of counts, with the exception of bacterial endospores, was observed after processing. All processed samples analyzed were devoid of salmonellae, Listeria monocytogenes, and Escherichia coli.
Although commonly used processing methods of Ruspolia differens were effective in reducing microbial load, bacterial endospores were hardly eliminated and could pose a health hazard to consumers; thus, improved handling of R. differens along the food chain could reduce such risks.
The aim of this study was to investigate the survival of Salmonella Enteritidis, Staphylococcus aureus and Listeria monocytogenes in salted and marinated anchovy (Engraulis encrasicholus). Total viable counts (TVCs), lactic acid bacteria, Enterobacteriaceae, and yeasts/molds were also enumerated. Initially, TVC was as high as 5.5 log10 cfu/g, but the population dropped down to 3.2 and 2.2 log10 CFU/g for salted and marinated anchovy, respectively. S. aureus was the most salt‐tolerant and L. monocytogenes was the most acid‐tolerant microorganism. A biphasic inactivation of S. Enteriditis and L. monocytogenes was apparent during the 8‐hr marination process, implying adaptation and resistance to low pH. Results suggest that salting or marinating of anchovy creates an environment in which pathogenic bacteria are inactivated. However, inherent resistance or possible adaptation to stresses can result to prolonged inactivation times; hence it is important to avoid contamination with high numbers of food‐borne pathogens.
Many food‐borne bacterial pathogens can survive at low pH and aw, especially in cases in which they might adapt to the imposed stresses and become resistant. Knowing the time required to reduce food‐borne pathogens is of great interest for ensuring safety of traditional seafood.
Posted in Enterobacteriaceae, Food Hygiene, Food Inspections, Food Micro Blog, Food Microbiology, Food Microbiology Blog, Food Pathogen, Food Safety, Food Testing, lactic acid bacteria, Listeria, Listeria monocytogenes, Moulds, Salmonella, Staphylococcus aureus, Total Viable Count, Uncategorized, Yeasts
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Legume seeds and sprouts are a rich source of phytoestrogens in the form of isoflavonoids. For the first time, lactic acid fermentation of four types of legume sprouts was used to increase the content of isoflavonoids and microbiological safety. After germination, the highest content of isoflavonoids was observed in the clover and chickpea sprouts, which amounted to 1.1 g/100 g dw., whereas the lactic acid fermentation allowed the increase to as much as 5.5 g/100 g dw. The most beneficial properties were shown by fermented chickpea sprouts germinated in blue light. During fermentation the number of lactic acid bacteria increased by 2 Log10CFU/mL (LU), whereas mold decreased by 1 LU, E.coli and Klebsiellasp. by 2 LU, Salmonella sp. and Shigella sp did not occur after fermentation, similar to Staphylococcus epidermidis, while S. aureus and S. saprophyticus decreased by 3 LU and in some trials were not detected.
FoodWorld 