Contamination pathways of spore-forming bacteria in a vegetable cannery

Evaluation of the Handling Practices and Risk Perceptions of Dried Wood Ear Mushrooms in Asian Restaurants in the United States

In late 2020, dried wood ear mushrooms, a low-moisture food ingredient that had been imported and sold to restaurants, were linked to a foodborne outbreak of Salmonella Stanley, which sickened 55 individuals across the United States. These mushrooms are commonly used in Asian cuisine. It is unclear if the contaminated dried wood ear mushrooms that caused the foodborne illnesses were improperly handled during preparation. The objectives of this study are to assess the handling practices, risk perceptions, and food recall experiences of dried wood ear mushrooms in restaurant kitchens among Asian restaurant managers and chefs. We conducted a series of telephone interviews with managers and chefs of Asian restaurants in the United States who used dried wood ear mushrooms in making dishes. After reaching information saturation, a total of 25 restaurant managers and chefs participated in the interview. Our results showed that 76% of the participants did not keep track of package information, such as expiration date and lot number, and many participants reported using cold water for rehydration. Wood ear mushrooms were blanched before being used in all cold dishes and most stir-fry dishes, but less commonly in stew or ramen. Some participants (16%) did not view dried wood ear mushrooms as a raw food ingredient, and 16% did not perceive that low-moisture food ingredients constituted microbiological food safety risks. The majority of the participants had heard of food recalls, but only 17% knew about the dried wood ear mushroom recall, and even fewer had heard of food recalls of other low-moisture foods, like nuts and seeds (9%), and flour (4%). While this study shares similarities with previously published studies evaluating the handling practices of consumers and restaurant employees with respect to meat and poultry, it makes a distinctive contribution to the field of food safety as the first-of-its-kind to study the handling practices of a low-moisture food ingredient: dried wood ear mushrooms. This unique ethnic food ingredient has been associated with a past outbreak and multiple recalls in the United States. The findings of the study show the need to develop food safety educational programs that are tailored toward Asian restaurant food handlers and provide guidance to develop risk communication strategies for this niche audience.

Identification and control of gas-producing bacteria isolated from the swollen bagged soy sauce

The swelling of soy sauce bags seriously affects product quality and causes food safety problems, which has become an urgent problem to solve in the condiment industry. Here, gas-producing bacteria in the swollen bagged soy sauce were isolated and identified to provide an effective control method for inhibiting their growth and solving the swelling of soy sauce bags. It was found that three gas-producing bacteria isolated from the swollen bagged soy sauce were confirmed as Bacillus amyloliquefaciens (G1), Bacillus sp. (G2) and Bacillus subtilis (P3) using 16S rDNA analysis. The strains' morphologies, growth rates, and physiological and biochemical characteristics were also compared. Further studies yielded the optimal growth time, temperature and pH for the three gas-producing bacteria (B. amyloliquefacien: 24 h, 37 °C, and pH 7; Bacillus sp.: 18 h, 30 °C, and pH 6.5-7.5; B. subtilis: 36 h, 30 °C, and pH 8). Bacillus sp. was more salt tolerant than the other two. Then the antibacterial effect of the combination was tested by the physicochemical index. The results showed that filtering through a 0.22 μm inorganic micro-filtration membrane, sterilizing at 121 °C for 2 min, and adding 1 g/kg potassium sorbate was effective methods to inhibit three gas-producing bacteria and control the swelling of soy sauce.

Genetic and technological characterization of lactic acid bacteria isolated from tropically grown fruits and vegetables

Phyllosphere microorganisms are common contaminants of fruit or vegetable containing foods. The aim of this study was to identify and characterize lactic acid bacteria isolated from fruits and vegetables from Reunion Island, regarding possible application in food. Among 77 isolates, a large diversity of species was observed, with isolates belonging to Lactobacillus plantarum (3 isolates), other species of Lactobacillus (3), Lactococcus lactis (13), Leuconostoc pseudomesenteroides (25), Leuconostoc lactis (1), Leuconostoc mesenteroides (7), Leuconostoc citreum (14), Weissella cibaria (4), Weissella confusa (4), other species of Weissella (2) and Fructobacillus tropaeoli (1). Several of these species, although belonging to lactic acid bacteria, are poorly characterized, because of their low occurrence in dairy products. Lactobacillus, Lactococcus, Leuconostoc and Weissella isolates were classified by (GTG)₅ fingerprinting in 3, 6, 21 and 10 genetic groups, respectively, suggesting a large intra-species diversity. Several Weissella and Lactobacillus isolates were particularly tolerant to acid and osmotic stress, whereas Lc. pseudomesenteroides 60 was highly tolerant to oxidative stress. Isolates of Weissella 30, 64 and 58, Leuconostoc 60 and 12b, Lactobacillus 75 and Fructobacillus 77 present relevant characteristics for their use as starters or as preservative cultures for fruits and vegetables.

Text mining tools for extracting information about microbial biodiversity in food

Information on food microbial diversity is scattered across millions of scientific papers. Researchers need tools to assist their bibliographic search in such large collections. Text mining and knowledge engineering methods are useful to automatically and efficiently find relevant information in Life Science. This work describes how the Alvis text mining platform has been applied to a large collection of PubMed abstracts of scientific papers in the food microbiology domain. The information targeted by our work is microorganisms, their habitats and phenotypes. Two knowledge resources, the NCBI taxonomy and the OntoBiotope ontology were used to detect this information in texts. The result of the text mining process was indexed and is presented through the AlvisIR Food on-line semantic search engine. In this paper, we also show through two illustrative examples the great potential of this new tool to assist in studies on ecological diversity and the origin of microbial presence in food.

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We present new text-mining tools to extract information in food microbiology.

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The results of the extraction are available in an on-line semantic search engine.

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Taxa, habitats, phenotypes and links between them can be queried in PubMed abstracts.

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Text-mining tools could assist to browse past and recent scientific literature.

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Two use-cases are presented: fruit microbiota and spore-forming bacteria in food.

Bacteriocins: Novel Solutions to Age Old Spore-Related Problems?

Bacteriocins are ribosomally synthesized antimicrobial peptides produced by bacteria, which have the ability to kill or inhibit other bacteria. Many bacteriocins are produced by food grade lactic acid bacteria (LAB). Indeed, the prototypic bacteriocin, nisin, is produced by Lactococcus lactis, and is licensed in over 50 countries. With consumers becoming more concerned about the levels of chemical preservatives present in food, bacteriocins offer an alternative, more natural approach, while ensuring both food safety and product shelf life. Bacteriocins also show additive/synergistic effects when used in combination with other treatments, such as heating, high pressure, organic compounds, and as part of food packaging. These features are particularly attractive from the perspective of controlling sporeforming bacteria. Bacterial spores are common contaminants of food products, and their outgrowth may cause food spoilage or food-borne illness. They are of particular concern to the food industry due to their thermal and chemical resistance in their dormant state. However, when spores germinate they lose the majority of their resistance traits, making them susceptible to a variety of food processing treatments. Bacteriocins represent one potential treatment as they may inhibit spores in the post-germination/outgrowth phase of the spore cycle. Spore eradication and control in food is critical, as they are able to spoil and in certain cases compromise the safety of food by producing dangerous toxins. Thus, understanding the mechanisms by which bacteriocins exert their sporostatic/sporicidal activity against bacterial spores will ultimately facilitate their optimal use in food. This review will focus on the use of bacteriocins alone, or in combination with other innovative processing methods to control spores in food, the current knowledge and gaps therein with regard to bacteriocin-spore interactions and discuss future research approaches to enable spores to be more effectively targeted by bacteriocins in food settings.