Investigating processing practices and microbiological quality of minimally processed vegetables in Brazil.

Minimally processed vegetables (MPVs) are marketed as convenient and healthy choices for consumers. However, the absence of post-commercialization treatments raises concerns about their microbiological safety. This study investigated the processing practices of 28 Brazilian MPV plants and compared the microbiological quality of these products with fresh counterparts in the city of Sao Paulo, Brazil. Through cluster analysis, the processing plants were categorized into two groups: group 1 (nineteen plants) primarily uses chemical substances in the washing step, while group 2 (nine plants) avoids chemical use but employs similar rinsing practices. Microbiological analysis of 100 samples (49 unprocessed and 51 MPVs) revealed no significant differences in microbial group counts (Enterobacteriaceae, coliforms, and E. coli) between the in natura (unprocessed) and MPV products. However, the prevalence of E. coli was higher in natura vegetables than in MPVs. The results indicated the presence of Salmonella DNA (from either dead or live cells or residual DNA) in 4 samples (3 in natura and 1 MPV) using conventional PCR, suggesting the presence of the pathogen in these samples. Listeria monocytogenes was absent, but Listeria innocua was found in two unprocessed products. The study suggests that certain MPVs have microbial loads similar to unprocessed vegetables, potentially serving as carriers for pathogen transmission. These findings emphasize the importance of understanding practices in Brazilian MPV processing plants, informing the implementation of control measures to improve MPV safety and shelf-life, thus ensuring microbiological safety.

Minimally Processed Vegetables in Brazil: An Overview of Marketing, Processing, and Microbiological Aspects.

The global demand for minimally processed vegetables (MPVs) has grown, driven by changes in the population's lifestyle. MPVs are fresh vegetables that undergo several processing steps, resulting in ready-to-eat products, providing convenience for consumers and food companies. Among the processing steps, washing-disinfection plays an important role in reducing the microbial load and eliminating pathogens that may be present. However, poor hygiene practices can jeopardize the microbiological quality and safety of these products, thereby posing potential risks to consumer health. This study provides an overview of minimally processed vegetables (MPVs), with a specific focus on the Brazilian market. It includes information on the pricing of fresh vegetables and MPVs, as well as an examination of the various processing steps involved, and the microbiological aspects associated with MPVs. Data on the occurrence of hygiene indicators and pathogenic microorganisms in these products are presented. The focus of most studies has been on the detection of Escherichia coli, Salmonella spp., and Listeria monocytogenes, with prevalence rates ranging from 0.7% to 100%, 0.6% to 26.7%, and 0.2% to 33.3%, respectively. Foodborne outbreaks associated with the consumption of fresh vegetables in Brazil between 2000 and 2021 were also addressed. Although there is no information about whether these vegetables were consumed as fresh vegetables or MPVs, these data highlight the need for control measures to guarantee products with quality and safety to consumers.

Antiviral activity of glucosylceramides isolated from Fusarium oxysporum against Tobacco mosaic virus infection.

Natural elicitors derived from pathogenic microorganisms represent an ecologic strategy to achieve resistance in plants against diseases. Glucosylceramides (GlcCer) are classified as neutral glycosphingolipids. GlcCer were isolated and purified from Fusarium oxysporum mycelium. F. oxysporum is a plant pathogenic fungus, abundant in soil and causing severe losses in economically important crops such as corn, tobacco, banana, cotton and passion fruit. In this study we evaluate the capacity of GlcCer in inducing resistance in N. tabacum cv Xanthi plants against Tobacco mosaic virus (TMV). Spraying tobacco plants with GlcCer before virus infection reduced the incidence of necrotic lesions caused by TMV. In addition, plants already infected with the virus showed a reduction in hypersensitive response (HR) lesions after GlcCer treatment, suggesting an antiviral effect of GlcCer. Our investigations showed that GlcCer stimulates the early accumulation of H2O2 and superoxide radicals. In addition, the expression of PR-1 (pathogenesis-related 1, with suggested antifungal action), PR-2 (ß-1,3-glucanase), PR-3 (Chitinase), PR-5 (Osmotin), PAL (Phenylalanine ammonia-lyase), LOX (Lipoxygenase) and POX (Peroxidase) genes was highly induced after treatment of tobacco plants with GlcCer and induction levels remained high throughout a period of 6 to 120 hours. Our experiments demonstrate that GlcCer induces resistance in tobacco plants against infection by TMV.

Glucosylceramides From Lomentospora prolificans Induce a Differential Production of Cytokines and Increases the Microbicidal Activity of Macrophages.

Lomentospora prolificans is an emerging opportunistic fungus with a high resistance to antifungal agents and it can cause localized infections in immunocompetent patients and disseminated infections with a high mortality rate in immunosuppressed patients. Glucosylceramides (GlcCer) are synthetized in the majority of known fungal pathogens. They are bioactive molecules presenting different functions, such as involvement in fungal growth and morphological transitions in several fungi. The elucidation of the primary structure of the fungal surface glycoconjugates could contribute for the understanding of the mechanisms of pathogenicity. In this work, GlcCer species were isolated from mycelium and conidia forms of L. prolificans and their chemical structures were elucidated by mass spectrometry (ESI-MS). GlcCer purified from both forms presented a major species at m/z 750 that corresponds to N-2-hydroxyhexadecanoyl-1-ß-D-glucopyranosyl-9-methyl-4,8-sphingadienine. Monoclonal antibodies against GlcCer could recognize L. prolificans GlcCer species from mycelium and conidia, suggesting a conserved epitope in fungal GlcCer. In addition, in vivo assays showed that purified GlcCer species from both forms was able to induce a high secretion of pro-inflammatory cytokines by splenocytes. GlcCer species also promote the recruitment of polymorphonuclear, eosinophils, small peritoneal macrophage (SPM) and mononuclear cells to the peritoneal cavity. GlcCer species were also able to induce the oxidative burst by peritoneal macrophages with NO and superoxide radicals production, and to increase the killing of L. prolificans conidia by peritoneal macrophages. These results indicate that GlcCer species from L. prolificans are a potent immune response activator.