Abstract
Practical Applications
Improved WPC based coating containing W. saturnus can be applied on surface of roasted peanuts to prevent growth of A. flavus and aflatoxin production.
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Category Archives: Microbiology
Research – Effects of edible coating containing Williopsis saturnus var. saturnus on fungal growth and aflatoxin production by Aspergillus flavus in peanuts
RASFF Alerts – Animal Feed – Salmonella – Rapeseed Meal – Fish Meal
Research – Aflatoxin cross‐contamination during mixing of shelled almonds
Abstract
Practical applications
Shelled almonds have an atypical aflatoxin distribution that appears consistent with a combination of two distributions: first, infrequent highly contaminated nuts and second, a uniform low‐level aflatoxin contamination. This second distribution appears to come from cross‐contamination during postharvest processing, but this has not been previously tested. Results of this study confirmed that aflatoxin can transfer between contaminated nuts and uncontaminated nuts via simple mechanical mixing contact, as would occur during postharvest processing. Almond producers will want to take this finding into account when reviewing their processing and cleaning procedures and reduce any opportunity for nut to nut cross‐contamination by removing contaminated nuts as early as possible and routinely cleaning processing equipment.
Research – Cold plasma enhances the efficacy of aerosolized hydrogen peroxide in reducing populations of Salmonella Typhimurium and Listeria innocua on grape tomatoes, apples, cantaloupe and romaine lettuce
In the present study, we investigated whether cold plasma activation affected the efficacy of aerosolized hydrogen peroxide against S. Typhimurium and L. innocua. Stem scars and smooth surfaces of grape tomatoes, surfaces of Granny Smith apples and Romaine lettuce (both midrib and upper leaves) and cantaloupe rinds were inoculated with two-strain cocktails of S. Typhimurium and 3-strain cocktails of L. innocua. The inoculated samples were treated with 7.8% aerosolized H2O2 with and without cold plasma for various times. For all fresh produce items and surfaces, cold plasma significantly (P < 0.05) improved the efficacy of aerosolized H2O2 against Salmonella and L. innocua. Without cold plasma activation, H2O2 aerosols only reduced populations of Salmonella by 1.54–3.17 log CFU/piece while H2O2 with cold plasma achieved 2.35–5.50 log CFU/piece reductions of Salmonella. L. innocua was more sensitive to the cold plasma-activated H2O2 than Salmonella. Cold plasma activated H2O2 aerosols reduced Listeria populations by more than 5 log CFU/piece on all types and surfaces of fresh produce except for the tomato stem scar area. Without cold plasma, the reductions by H2O2 were only 1.35–3.77 log CFU/piece. Overall, our results demonstrated that cold plasma activation significantly enhanced the efficacy of H2O2 mist against bacteria on fresh produce.
Research -Vertical transmission of Salmonella Enteritidis with heterogeneous antimicrobial resistance from breeding chickens to commercial chickens in China
Human salmonellosis caused by the consumption of eggs and chicken meat contaminated with Salmonella Enteritidis has become a continuing public health concern worldwide. In this study we adopted whole genome sequencing (WGS) to determine the genetic relationship and antimicrobial resistance of S. enterica strains isolated from a poultry breeding enterprise that consists of one breeding chicken farm, one egg hatchery and one commercial chicken farm. A total of 148 S. enterica including 147 S. Enteritidis strains were isolated from 2100 fecal swab samples, with 16 (5.3 %, 16/300) from breeding chicken farm, 38 (4.2 %, 38/900) from egg hatchery and 94 (10.4 %, 94/900) from commercial chicken farm. WGS revealed that all 147 S. Enteritidis strains belonged to ST11, and further divided into 4 different ribosomal STs and 64 core genome STs. Single nucleotide polymorphism typing suggested the presence of the vertical transmission of S. Enteritidis from breeding chicken to commercial chicken. Three different antimicrobial-resistant plasmids including one blaCTX-M-14-carrying plasmid and two virulence-resistance plasmids were characterized, resulting in the heterogeneous antimicrobial resistance of clonally related S. Enteritidis strains. Routine surveillance in breeding chicken farms is conducive to the control of S. Enteritidis from farm to fork.
Research – Salmonella sensitivity to sodium hypochlorite and citric acid in washing water of lettuce residues
Salmonella spp. is one of the main lettuce pathogens and should be inactivated during the disinfection of these vegetables before consumption. In minimally processed vegetable industries, residues of organic matter can prevent the inactivation of this pathogen by disinfectants. The objective of the present work was to evaluate the inactivation of Salmonella isolated from organic lettuce to sodium hypochlorite (25 and 50 ppm) and citric acid (0.5 and 1%) in washing water added with lettuce residues. To do so, a washing water with lettuce residues was elaborated, and Salmonella was added in the order of 106 CFU/ml. Thereafter, each sanitizer was added separately to evaluate its effect on reducing Salmonella counts. After 1, 2, 3, 4, 5, 10, and 15 min of contact with the sanitizers, serial dilutions using neutralizer (0.5% sodium thiosulfate) were performed and each dilution was sown in Xylose‐Lysine‐Desoxycholate medium. Total aerobic mesophilic counts of wash water with lettuce residues before testing (without Salmonella) and after 15 min of exposure to each sanitizer (with Salmonella) were also performed. In addition, the free chlorine still present in the samples after the contact of sodium hypochlorite with lettuce residues for 15 min. The results demonstrated that 50 and 25 ppm sodium hypochlorite could reduce 6 log CFU/ml of Salmonella in 1 and 3 min of contact, respectively, while 0.5 and 1% citric acid was able to reduce 1.26 and 1.74 log CFU/ml respectively from the same microorganism within 15 min of contact. The total aerobic mesophilic counts of the wash water before being tested were, on average, 1.5 log CFU/ml. After addition of Salmonella, with 15 min of contact with the sanitizer, the results of total counts showed the same magnitude as the Salmonella counts. Organic matter may have reacted with the free chlorine present, reducing chlorine concentrations, since values of 30.4 ppm were observed when the initial concentration should be 50 and 17.1 ppm when the initial concentration should be 25 ppm. Based on the results, sodium hypochlorite demonstrated a greater microbial reduction capacity in wash water with lettuce residues, indicating that it is more appropriate to avoid cross‐contamination between batches during sanitation of lettuce in washing tanks.
Research – Effect of high hydrostatic pressure on Salmonella spp inactivation and meat-quality of frozen chicken breast
The aim of this study was to evaluate the effect of the pressure level and holding time on the Salmonella spp inactivation during HHP processing in frozen chicken breast fillets. Once identified the most effective process, meat quality (color and texture) was evaluated. Results showed that the treatments at 500 MPa for 1 min and 400 MPa for 5 min were enough to guarantee Salmonella spp inactivation in frozen chicken breast fillets. With respect to quality parameters, an extension of shelf life is expected with both treatments, as counts of indigenous microbiota were below the detectable level (<2 logs CFU/g). However, chromatic parameters and texture profile of the fillets treated with HHP suffered significant changes. Even so, the treatment of 500 MPa for 1 min was more effective at preserving chromatic parameters than treatment of 400 MPa for 5 min. The texture profile between fillets treated was not significantly different.
Research – Environmental persistence and virulence of Salmonella spp. isolated from a poultry slaughterhouse
Salmonella spp. is responsible for severe foodborne disease, and is one of the main agents involved in foodborne outbreaks worldwide. Contamination occurs mainly as a result of poultry and egg consumption since they can carry some serotypes pathogenic to humans. The aim of the study was to evaluate the persistence and pathogenic potential of Salmonella spp. (n = 40) isolated from poultry slaughterhouse mats, using adhesion and invasion assays, antimicrobial susceptibility by disc diffusion, and biofilm production as phenotypic tests and genotypic analyses. Polystyrene mats presented 3.2 times greater chance of isolating Salmonella than canvas mats. Besides, we observed resistance to tetracycline (17.5%), ampicillin (10%), cefotaxime (7.5%), trimethoprim-sulfamethoxazole (5%), and chloramphenicol (2.5%). All strains possessed the invA, sipB, sipD, ssaR, sifA, sitC, iroN, tolC, flgK, fljB, and flgL genes. The genes sopB and sipA were both present in 92.5% of the isolates, while sopD and spvB were observed in 90% and 32.5% of strains, respectively. All strains adhered to and invaded HeLa cells. Regarding biofilm production, 31 (77.5%) strains were able to produce biofilm on polystyrene microplates. Using PFGE, we detected the persistence of clones in the environment for up to 18 fromthe 20 weeks. The ability of these strains to produce a biofilm and thus persist in the environment and disperse through contact surfaces in the processing plant favors the contamination of food, aggravated by the pathogenic potential of these isolates demonstrated by their adhesion capacity, invasion and resistance to various antibiotic agents.
Research – Prevalence and identification of Aspergillus and Penicillium species isolated from peanut kernels in central Myanmar
Abstract
Practical applications
In developing countries like Myanmar, there are lack of food safety practices and policies regarding the food storage, handling, and farmer education. The current study indicates the different storage methods for peanut kernels at farm level and their influence on prevalence of fungi. The study will give a deep insight to the policy makers to design food safety practices at farm level and educate the farmers to adopt the better practices to assure the consumer health and satisfaction in developing countries.
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