Despite good manufacturing practices and rigorous cleaning and sanitizing procedures established in dairy processing plants, microbiological contamination remains the main cause of products being ...non-compliant and/or atypical and hence not fit for human consumption. The objective of this study was to isolate, identify and characterize bacteria, yeasts and molds associated with substandard dairy products in Canada and to create a collection of reference isolates. In addition to conventional microbiological characterization, each isolate was tested for biofilm-forming ability and susceptibility to heat, antimicrobial agents, and common industrial disinfectants. Among the 105 microbial strains isolated from pasteurized milk, cream, and cheese samples, 24 bacterial isolates, belonging mainly to the genus Pseudomonas, were shown to be moderate or strong biofilm producers in 96-well plates and highly resistant to peracetic acid (100 ppm, 5 min contact time) and sodium hypochlorite (70 ppm, 5 min contact time). In addition, 56 bacterial isolates, including Acinetobacter baumannii, Enterobacter bugandensis, Klebsiella pneumoniae and Pseudomonas spp., were found resistant to ampicillin, fosfomycin and/or ceftriaxone, while 14 others, such as Bacillus spp. and Macrococcus spp., withstood a heat treatment equivalent to low-temperature long-time pasteurization (63°C for 30 min). This descriptive study provides new information on potential problematic microorganisms in dairies and will guide the development of novel control strategies intended to prevent and reduce microbiological contamination and the associated economic losses.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Cinnamaldehyde is a major constituent of cinnamon essential oils produced by aromatic cinnamon plants. This compound has been reported to exhibit antimicrobial properties in vitro in laboratory media ...and in animal feeds and human foods contaminated with disease-causing bacteria including Bacillus cereus, Campylobacter jejuni, Clostridium perfringens, Escherichia coli, Listeria monocytogenes, and Salmonella enterica. This integrated review surveys and interprets our current knowledge of the chemistry, analysis, safety, mechanism of action, and antibiotic activities of cinnamaldehyde in food animal (cattle, lambs, calves, pigs, poultry) diets and in widely consumed liquid (apple, carrot, tomato, and watermelon juices, milk) and solid foods. Solid foods include various fruits (bayberries, blueberries, raspberries, and strawberries), vegetables (carrots, celery, lettuce, spinach, cucumbers, and tomatoes), meats (beef, ham, pork, and frankfurters), poultry (chickens and turkeys), seafood (oysters and shrimp), bread, cheese, eggs, infant formula, and peanut paste. The described findings are not only of fundamental interest but also have practical implications for food safety, nutrition, and animal and human health. The collated information and suggested research needs will hopefully facilitate and guide further studies needed to optimize the use of cinnamaldehyde alone and in combination with other natural antimicrobials and medicinal antibiotics to help prevent and treat food animal and human diseases.
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IJS, KILJ, NUK, PNG, UL, UM, UPUK
3.
Microbial spoilage of vegetables, fruits and cereals Alegbeleye, Oluwadara; Odeyemi, Olumide Adedokun; Strateva, Mariyana ...
Applied Food Research,
June 2022, 2022-06-00, 2022-06-01, Volume:
2, Issue:
1
Journal Article
Peer reviewed
Open access
•Plant based foods are in high demand because they improved wellbeing and longevity.•Spoilage of plant commodities routinely occurs all over the world.•Spoilage is due to various factors leading to ...significant wastage.•It is important to manage microbial spoilage and optimize produce chains.
Plant based foods are in high demand because nutritional epidemiology has linked them to improve wellbeing and longevity. Spoilage of plant commodities routinely occurs all over the world due to various factors leading to significant wastage. Factors that contribute to and influence spoilage of fruits, vegetables and cereals including environmental factors such as pH, temperature and oxygen, as well as other factors such as some consumer attitudes have been elucidated by several studies and are summarized herein. This review also discusses some of the sources and routes of spoilage microorganisms to plant produce such as cultivation input and post-harvest practices. Furthermore, the mechanisms of fruits, vegetables and cereals spoilage are explored. Management and control of spoilage including alternative uses for overly ripen or otherwise surplus produce such as for the development of nutritious food products, as animal feed and other biotechnological applications like bioremediation are also discussed. Overall, it is important to manage microbial spoilage and optimize produce cultivation-supply chains all around the world to mitigate the associated environmental, nutritional and food security/safety impacts.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
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•Research data on strain variability in biofilm formation are compiled.•More data are available for foodborne pathogens than for spoilage microorganisms.•Molecular/physiological ...aspects likely linked to strain differences are suggested.•Means of quantitative description of biofilm strain variability are presented.•Data gaps and future research objectives are described and discussed.
The inherent differences in microbial behavior among identically treated strains of the same microbial species, referred to as “strain variability”, are regarded as an important source of variability in microbiological studies. Biofilms are defined as the structured multicellular communities with complex architecture that enable microorganisms to grow adhered to abiotic or living surfaces and constitute a fundamental aspect of microbial ecology. The research studies assessing the strain variability in biofilm formation are relatively few compared to the ones evaluating other aspects of microbial behavior such as virulence, growth and stress resistance. Among the available research data on intra-species variability in biofilm formation, compiled and discussed in the present review, most of them refer to foodborne pathogens as compared to spoilage microorganisms. Molecular and physiological aspects of biofilm formation potentially related to strain-specific responses, as well as information on the characterization and quantitative description of this type of biological variability are presented and discussed. Despite the considerable amount of available information on the strain variability in biofilm formation, there are certain data gaps and still-existing challenges that future research should cover and address. Current and future advances in systems biology and omics technologies are expected to aid significantly in the explanation of phenotypic strain variability, including biofilm formation variability, allowing for its integration in microbiological risk assessment.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Italian traditional mozzarella is a high moisture table cheese that is sold packaged in water for preserving freshness. Despite of the high foreign demand, high perishability limits export. For ...extending shelf life, the dairy industries have long been engaged in controlling the growth of spoilage microflora, which is the main responsible of alteration. The present paper describes the results of a study that aimed to assess if using acidified brine instead of water, the growth of these microorganisms could be delayed. A suitable brine was first developed, based on calcium lactate and lactic acid, that did not impair the sensory characteristics of the cheese. Then, the shelf-life study was carried out, and the results revealed a significant delay of the growth of total mesophilic bacteria, Pseudomonas spp. and Enterobacteriaceae. The sensory characteristics of the cheese remained within the acceptability limits until 21 days and, compared with the sample stored in water, the shelf life was extended of more than 50% Very interestingly, the experimental brine also prevented the occurrence of the blue discoloration defect, known to be caused by Pseudomonas fluorescens. Even though further investigation is needed, the results obtained can open new marketing perspectives for producers of traditional mozzarella.
•A low pH calcium lactate brine was developed for preserving traditional mozzarella.•The brine delayed the growth of spoilage bacteria.•The brine did not impact on the sensory characteristics and proteolysis.•Shelf-life of mozzarella was improved by more than 50%.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Foul-smelling odors are main quality defects of dry-cured ham, which are connected with the excessive degradation of the structural proteins and excessive oxidation of lipids caused by the abnormal ...growth of spoilage microorganisms, threatening the development of dry-cured ham industry. Characterizing the key microorganisms and metabolites resulted in the spoilage of dry-cured ham, and discussing the relationship between spoilage microorganisms and metabolites are the key aspects to deeply understand the formation mechanism of off-odor in dry-cured ham. Until now, there is no detailed discussion or critical review on the role of spoilage microorganisms in developing the off-odor of dry-cured ham, and the regulation of off-odor and spoilage microorganisms by starter cultures has been not discussed. This review shows the recent achievement in the off-odor formation mechanism of dry-cured ham, and outlines the potential regulation of off-odor defects in dry-cured ham by starter cultures. Results from current research show that the abnormal growth of Lactic acid bacteria, Micrococcaceae, Enterobacteriaceae, Yeasts and Molds plays a key role in developing the off-odor defects of dry-cured ham, while the key spoilage microorganisms of different type hams are discrepant. High profile of aldehydes, acids, sulfur compounds and biogenic amines are responsible for off-odor development in spoiled dry-cured ham. Several starter cultures derived from these species of Staphylococcus, Penicillium, Debaryomyces, Pediococcus and Lactobacillus show a great potential to prevent microbiological hazards and improve flavor quality of dry-cured ham, whereas, the ecology, function and compatibility of these starter cultures with the processing parameters of dry-cured ham need to be further evaluated in the future.
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BFBNIB, GIS, IJS, KISLJ, NUK, PNG, UL, UM, UPUK
This study estimates the shelf life of vacuum packed beef meat (three muscles: striploin (longissimus thoracis et lumborum, LTL), tenderloin (psoas major, PM) and outside chuck (trapezius thoracis, ...TT)) at refrigeration temperatures (0 °C–10 °C) based on modelling the growth of two relevant groups of spoilage microorganisms: lactic acid bacteria (LAB) and Enterobacteriaceae. The growth models were developed combining a two-step and a one-step approach. The primary modelling was used to identify the parameters affecting the growth kinetics, guiding the definition of secondary growth models. For LAB, the secondary model included the effect of temperature and initial pH on the specific growth rate. On the other hand, the model for Enterobacteriaceae incorporated the effect of temperature on the specific growth rate and the lag phase; as well as the effect of the initial pH on the specific growth rate, the lag phase and the initial microbial count. We did not observe any significant effect of the type of muscle on the growth kinetics. Once the equations were defined, the models were fitted to the complete dataset using a one-step approach. Model validation was carried out by cross-validation, mitigating the impact of an arbitrary division between training and validation sets. The models were used to estimate the shelf life of the product, based on the maximum admissible microbial concentration (7 log CFU/g for LAB, 5 log CFU/g for Enterobacteriaceae). Although LAB was the dominant microbiota, in several cases, both LAB and Enterobacteriaceae reached the critical concentration practically at the same time. Furthermore, in some scenarios, the end of shelf life would be determined by Enterobacteriaceae, pointing at the potential importance of non-dominant microorganisms for product spoilage. These results can aid in the implementation of effective control measures in the meat processing industry.
•The shelf life of vacuum packed beef (VPB) was estimated using predictive models.•Predictive models were tested by cross-validation.•Uncertainty was quantified and illustrated in the estimations by Monte Carlo simulations.•Higher initial pH (> 5.8) of the meat reduced VPB shelf life while muscle type did not•Although LAB were dominant, in certain cases Enterobacteriaceae reached their critical limit earlier.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Volatile organic compounds (VOCs) origination during fish spoilage is attributed to either decomposition of fish constituents or metabolic activity of spoilage bacteria. To identify microbiological ...spoilage markers it is essential to know which VOCs are microbial metabolites. VOCs produced in sterile fish juice agar (FJA) model substrate made from gilt-head sea bream (Sparus aurata) flesh juice, inoculated or not with spoilage bacteria isolated from sea bream fillets were detected using SPME/GC-MS technique. Three groups of spoilage bacteria (Pseudomonas, Shewanella and Carnobacterium/Lactobacillus strains) were used to inoculate Petridishes with FJA and stored at 0 and 15 °C under air and commercial Modified Atmosphere Package (MAP CO2: 60%, O2: 10%, N2: 30%). Bacterial growth was also monitored. VOCs that were detected in sterile substrate and their amounts were not higher in inoculated FJA were presumably of non-microbial origin. VOCs that were detected only in inoculated FJA were metabolic products of spoilage bacteria. Some of VOCs were associated with metabolic activity of a particular microbial group, e.g. ethyl esters were associated with Pseudomonas, while 2-, 3-methylbutanal and 3-hydroxy-2-butanone with LAB. Few microbial metabolites increased during storage showing their potential as spoilage markers of gilt-head sea bream and the possible use for rapid freshness assessment.
•Volatilome of spoilage bacteria was examined.•Some VOCs were found as non-microbial origin.•Some VOCs were associated with metabolic activity of a particular microbial group.•Some VOCs were found as potential chemical spoilage markers.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
Year-round access to good quality forage is a physiological priority for ruminants and an economic priority for farmers. Ensiling is a method for preserving moist crops based on organic acid ...production by lactic acid bacteria under anaerobic conditions. However, silage can be a vector for undesirable microorganisms, impairing crop preservation, animal performance or the health of both animals and humans.
Major problems in silage processing are due to failure to apply good manufacturing practice (GMP). To improve silage preservation and guarantee the quality of this animal feed, silage additives such as chemicals, enzymes and bacterial agents can be employed.
The purpose of the present paper is to review existing information on the desirable and undesirable microorganisms involved in silage processing, and possible methods, using GMP or silage additives, of limiting silage degradation and its economic effects and health impact on animals and humans.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
