Notes

Mechanical behaviors of hydrate-bearing sediment with different cementation spatial distributions in microscales.
The implementation of cleaning and sanitation at slaughterhouse level could represent the main factor for the control of such pathogen in the poultry meat processing line.This work aimed to estimate the inactivation kinetic parameters of four potential beer spoilage bacteria (Lactobacillus brevis DSM 6235, Lactobacillus casei ATCC 334, Pediococcus damnosus DSM 20289 and Pediococcus damnosus ATCC 29358) inoculated in brewing yeast submitted to acid washing with purposes of yeast recycle. The experiments were conducted at 4 °C in solutions with pH 1.5, pH 2, and pH 3 adjusted employing 85% phosphoric acid. The acid washing treatment of brewing yeasts in the most common pH used (pH 2.0) demanded almost 50 min for the first decimal reduction (δ) of L. brevis DSM 6235. Sensible strains to acid washing such as P. damnosus DSM 20289 demanded almost 70 min for 4 log reductions to be achieved. On the other hand, pH reduction of the acid washing from 2.0 to 1.5 allowed 4 log reduction of L. brevis DSM 6235) to be obtained in less than 50 min, without ruining brewer's yeast viability. Acid washing in pH 1.5 is a viable method for the inactivation of bacterial contaminants of brewing yeasts. Recycling of brewing yeasts through this approach may contribute to a more sustainable and environmental-friendly industry.Poland is one of the largest food producers in Europe, and the West Pomeranian region of Poland is a large producer of RTE food. Thus, the objective of this study was to determine the prevalence of Listeria sp. and L. monocytogenes (LM) in RTE foods manufactured by 13 selected Polish food producers whose processing plants are located in this region. In total, 650 samples of RTE foods, and 263 ingredients of salads and desserts were analyzed. Almost 18% of the RTE foods failed to meet the zero tolerance limit for Listeria, which means they should not be allowed for retail. LM was isolated from 13.5% of the samples, with counts of 10-100 CFU/g noted in half of them. Products with meat and dairy ingredients, and fish products, sandwiches, sprouts and sushi, were at the highest statistically significant risk of LM contamination. Four serogroups were identified among the LM isolated from RTE foods, of which the 4b-4d-4e serogroup was predominating. The samples most heavily contaminated with LM contained even 2 serogroups. Results were subjected to the cluster analysis and principal component analysis to determine correlations between food groups, food ingredients, producers, contamination level, and serogroups of LM.The safety of current UK industry practice (including shelf-life) for chilled, vacuum/modified atmosphere-packed fresh red meat (beef, lamb and pork) held at 3°C-8°C has been evaluated with respect to non-proteolytic Clostridium botulinum. UK industry typically applies a retail pack shelf-life at 3°C-8°C to 13 days for fresh red meat, with a maximum of 23 days for beef, 27 days for lamb, and 18 days for pork. An exposure assessment established that current commercial practice for fresh red meat provided strong protection with more than 1010 person servings marketed in the UK without association with foodborne botulism. A challenge test demonstrated that spores of non-proteolytic C. botulinum inoculated on chilled vacuum-packed fresh red meat did not lead to detectable neurotoxin at day 50 for beef, day 35 for lamb, or day 25 for pork (i.e. less then 40 pg type B toxin and type E toxin g-1 of meat). The products were visually spoiled many days before these end points. The exposure assessment and challenge test demonstrated the safety of current UK industry practices for the shelf-life of fresh, vacuum-packed beef, lamb and pork held at 3°C-8°C with respect to C. botulinum, and that botulinum neurotoxin was not detected within their organoleptic shelf-life.This research determined the concentration of trehalose, xylose and l-citrulline in fresh and fermented cucumbers and their utilization by Lactobacillus pentosus, Lactobacillus plantarum, Lactobacillus brevis and Lactobacillus buchneri. Targeted compounds were measured by HPLC and the ability of the lactobacilli to utilize them was scrutinized in fermented cucumber juice. Fresh cucumber juice was supplemented with trehalose, xylose and l-citrulline to observed mixed culture fermentations. Changes in the biochemistry, pH and colony counts during fermentations were monitored. Trehalose, xylose and l-citrulline were detected in fermentations to15.51 ± 1.68 mM, a fresh cucumber sample at 36.05 mM and in fresh and fermented cucumber samples at 1.05 ± 0.63 mM, respectively. Most of the LAB tested utilized trehalose and xylose in FCJM at pH 4.7. l-citrulline was utilized by L. buchneri and produced by other LAB. l-citrulline (12.43 ± 2.3 mM) was converted to ammonia (14.54 ± 3.60 mM) and the biogenic amine ornithine (14.19 ± 1.07 mM) by L. buchneri at pH 4.7 in the presence of 0.5 ± 0.2 mM glucose enhancing growth by 0.5 log CFU/mL. The use of a mixed starter culture containing L. buchneri aided in the removal of l-citrulline and enhanced the fermentation stability. The utilization of l-citrulline by L. buchneri may be a cause of concern for the stability of cucumber fermentations at pH 3.7 or above. This study identifies the use of a tripartite starter culture as an enhancer of microbial stability for fermented cucumbers.Lactic acid bacteria (LAB) are commonly used in soymilk fermentation to improve health-related functionality, but their contribution to sensory qualities is less valued. We characterized Lactobacillus harbinensis M1, Lactobacillus mucosae M2, Lactobacillus fermentum M4, Lactobacillus casei M8 and Lactobacillus rhamnosus C1 from naturally-fermented tofu whey, along with Streptococcus thermophilus ST3 from kefir XPL-1 fermented soymilk, to investigate their potential as starter cultures of fermented soymilk. They were characterized for antibiotic susceptibility, probiotic potential and their performance as starter cultures. All the LABs showed sensitivity to the tested antibiotics. L. casei M8 had strongest tolerance to synthetic gastrointestinal juice ( less then 1.0 log CFU/mL loss), as well as antagonistic effects towards five food-borne pathogens. GC/MS analysis showed that L. harbinensis M1 produced significantly higher abundance (P less then 0.05) of 2,3-butanedione (2.45 ppm) and acetoin (44.30 ppm), thus improving the overall sensory acceptability of fermented soymilk. The coding genes for the synthesis of 2,3-butanedione/acetoin (alsS, alsD, butA) were predicted from the whole-genome. A co-culture of L. harbinensis M1 and L. casei M8 produced a fermented soymilk product with both markedly improved flavor and good probiotic potential. It appears that L. harbinensis M1 has much potential for improving the organoleptic properties of fermented soymilk.Zygosaccharomyces rouxii represents the main spoilage cause of concentrated apple juice, leading to waste of products or recalls. Essential oils components derived from plants have been found to present antimicrobial activities against various microbes. However, few work has been reported about their antimicrobial activities against Z. rouxii in concentrated apple juice. In this work, reparameterized Gompertz equation was used to evaluate the antimicrobial activities of different antimicrobials to inhibit the growth of a Z. rouxii cocktail (6.3 lg colony forming units/mL) composed of six strains isolated from concentrated apple juice and two strains from honey and grape must. The obtained mathematical models presented that thymol, carvacrol and trans-cinnamaldehyde were the promising options to inhibit Z. rouxii in 30 oBrix apple juice, reaching a maximal decrease on yeast growth of around 99.65 ± 0.61%. Whereas other antimicrobials showed lower antimicrobial activities with a maximal growth decrease of ranging from 67.13 ± 3.62% to 13.38 ± 1.16%. Additionally, the sensorial characteristics were not affected when the antimicrobials assayed were applied at the effective concentrations in commercial apple juice product. This work provided a theoretical feasibility that thymol, carvacrol and trans-cinnamaldehyde could be applied as natural preservatives for the control of Z. rouxii-related spoilage in fruit juice industry.Carnobacterium maltaromaticum, Brochothrix thermosphacta and Serratia liquefaciens are common spoilage organisms found within the microbiome of refrigerated vacuum-packaged (VP) beef. Extending and predicting VP beef shelf-life requires knowledge about how spoilage bacteria growth is influenced by environmental extrinsic and intrinsic factors. Multifactorial effects of pH, lactic acid (LA) and glucose on growth kinetics were quantified for C. maltaromaticum, B. thermosphacta and S. liquefaciens within a heat shrink-wrapped VP commercial film containing a simulated beef medium. LA, pH, and undissociated lactic acid (UDLA) significantly affected bacterial growth rate (p less then 0.001), whereas 5.55 mM glucose produced a marginal effect. At 1.12 mM UDLA, growth rate and maximum population density decreased 20.9 and 3.5%, 56 and 7%, and 11 and 2% for C. maltaromaticum, B. thermosphacta, and S. liquefaciens, respectively.In this study, we evaluated the contributions of three bacteria (Pseudomonas versuta, Shewanella putrefaciens, and Aeromonas sobria) to the proteolysis, biogenic amines formation, volatile organic compounds accumulation, lipid oxidation, nucleotide catabolism, discoloration, and water migration of bream flesh during chilled storage. The results showed that P. versuta exhibited hydrolyzing activity against sarcoplasmic proteins, and all three strains could degrade myofibrillar proteins, specifically actin. The highest producer of putrescine was S. putrefaciens, which reached a maximum level 5.05 mg/kg after 14 days. Compared with the A. sobria group, hypoxanthine riboside degraded faster in samples inoculated with P. versuta or S. putrefaciens, A. sobria, P. versuta, and S. putrefaciens were responsible for the production of alcohol and aldehydes, whereas only S. putrefaciens produced thiophene and partial esters. Fish flesh inoculated with P. versuta, S. putrefaciens, and A. sobria presented slight green, yellow, and pink discoloration, respectively.Enteric viruses cause the majority of foodborne illnesses and common symptoms of many foodborne illnesses include vomiting, diarrhea, abdominal pain, and fever. Among the enteric viruses, human Norovirus (NoV) and hepatitis virus (HAV and HEV) are the main viruses suspected to cause foodborne outbreaks and represent a serious public health. The study presents survey tools of viruses in a wide variety of foodstuffs and results obtained during 56 foodborne outbreaks investigation in France between 2012 and 2017. 246 suspected foods were examined for the presence of four human enteric viruses (NoV GI and NoV GII, HAV or HEV) either using methods described in the EN ISO 15216-1 or in house methods. MSC-4381 All viral analysis of food samples were performed with the implementation of process control and an external amplification controls. Eighteen of 56 foodborne outbreaks investigated included at least one positive food sample (16/18 NoV, 1/18 HAV and 1/18 HEV). The genomic levels of four viruses detected ranged from less then 102 to 107 genome copies per g or per L.
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