Category Archives: Mesophilic Aerobes

Research – Microbial food spoilage: impact, causative agents and control strategies

Posted on August 14, 2024 by | Leave a comment

Nature

Abstract

Microbial food spoilage is a major contributor to food waste and, hence, to the negative environmental sustainability impacts of food production and processing. Globally, it is estimated that 15–20% of food is wasted, with waste, by definition, occurring after primary production and harvesting (for example, in households and food service establishments). Although the causative agents of food spoilage are diverse, many microorganisms are major contributors across different types of foods. For example, the genus Pseudomonas causes spoilage in various raw and ready-to-eat foods. Aerobic sporeformers (for example, members of the genera Bacillus, Paenibacillus and Alicyclobacillus) cause spoilage across various foods and beverages, whereas anaerobic sporeformers (for example, Clostridiales) cause spoilage in a range of products that present low-oxygen environments. Fungi are also important spoilage microorganisms, including in products that are not susceptible to bacterial spoilage due to their low water activity or low pH. Strategies that can reduce spoilage include improved control of spoilage microorganisms in raw material and environmental sources as well as application of microbicidal or microbiostatic strategies (for example, to products and packaging). Emerging tools (for example, systems models and improved genomic tools) represent an opportunity for rational design of systems, processes and products that minimize microbial food spoilage.

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Posted in Bacillus, Bacterial Spores, Food Spoilage, Mesophilic Aerobes, Microbial Spoilage, Spores

Research – Levels and types of microbial contaminants in different plant-based ingredients used in dairy alternatives

Posted on August 3, 2024 by | 1 comment

Science Direct

Abstract

In this study levels and types of microbial contaminants were investigated in 88 different plant-based ingredients including many that are used to manufacture dairy alternatives. Studied ingredients encompassed samples of pulses (pea, faba bean, chickpea, and mung bean), cereals/pseudocereals (oat, rice, amaranth and quinoa) and drupes (coconut, almond and cashew). The microbial analysis included: i) total viable count (TVC), ii) total aerobic mesophilic spore count (TMS), iii) heat resistant aerobic thermophilic spore count (HRTS), iv) anaerobic sulfite reducing Clostridium spore count (SRCS), and v) Bacillus cereus spore count (BCES). Microorganisms isolated from the counting plates with the highest sample dilutions were identified using 16S rRNA and MALDI-TOF MS analyses.

Many of the investigated ingredients showed a high proportion of spores as part of their total aerobic mesophilic counts. In 63 % of the samples, the difference between TVC and TMS counts was 1 Log10 unit or less. This was particularly the case for the majority of pea isolates and concentrates, faba bean isolates, oat kernels and flakes, and for single samples of chickpea isolate, almond, amaranth, rice, quinoa, and coconut flours. Concentrations of TVC ranged between <1.0 and 5.3 Log10 CFU/g in different samples, and TMS varied between <1.0 and 4.1 Log10 CFU/g. Levels of HTRS, BCES and SRCS were generally low, typically around or below the LOD of 1.0 Log10 CFU/g.

In total, 845 individual bacterial colonies were isolated belonging to 33 different genera. Bacillus licheniformis and B. cereus group strains were most frequently detected among Bacillus isolates, and these species originated primarily from pea and oat samples. Geobacillus stearothermophilus was the main species encountered as part of the HRTS. Among the Clostridium isolates, Clostridum sporogenes/tepidum were predominant species, which were mostly found in pea and almond samples. Strains with potential to cause foodborne infection or intoxication were typed using the PCR-based method for toxin genes detection. In the B. cereus group, 9 % of isolates contained the ces gene, 28 % contained hbl, 42 % cytK, and 69 % were positive for the nhe gene. Absence of the boNT-A and -B genes was confirmed for all isolated C. sporogenes/tepidum strains. Nearly all (98 %) B. licheniformis isolates were positive for the lchAA gene.

Insight into the occurrence of microbial contaminants in plant-based ingredients, combined with knowledge of their key inactivation and growth characteristics, can be used for the microbial risk assessment and effective design of plant-based food processing conditions and formulations to ensure food safety and prevent spoilage.

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Posted in Bacillus cereus, bacterial contamination, Clostridium, Clostridium sporogenes, Contaminated water, cross contamination, food contamination, Food Microbiology Research, Malditof, Mesophilic Aerobes, microbial contamination, Research

Research – Increasing the Safety and Storage of Pre-Packed Fresh-Cut Fruits and Vegetables by Supercritical CO2 Process

Posted on December 27, 2022 by | Leave a comment

MDPI

Abstract

This work presents a feasibility lab-scale study for a new preservation method to inactivate microorganisms and increase the shelf life of pre-packed fresh-cut products. Experiments were conducted on coriander leaves and fresh-cut carrots and coconut.
The technology used the combination of hydrostatic pressure (<15 MPa), low temperature (≤45 °C), and CO2 modified atmosphere packaging (MAP). The inactivation was achieved for the naturally present microorganisms (total mesophilic bacteria, yeasts and molds, total coliforms) and inoculated E. coli. Yeasts and molds and coliform were under the detection limit in all the treated samples, while mesophiles were strongly reduced, but below the detection limit only in carrots.
Inoculated E. coli strains were completely inactivated (>6.0 log CFU/g) on coconut, while a reduction >4.0 log CFU/g was achieved for carrots and coriander. For all the treated products, the texture was similar to the fresh ones, while a small alteration of colour was detected. Microbiological stability was achieved for up to 14 days for both fresh-cut carrots and coconut.
Overall, the results are promising for the development of a new mild and innovative food preservation technique for fresh food.

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Posted in Coliforms, Decontamination Microbial, E.coli, Food Micro Blog, Food Microbiology, Food Microbiology Blog, Food Microbiology Research, Food Microbiology Testing, MAP, Mesophilic Aerobes, microbial contamination, Microbial growth, Microbiological Risk Assessment, Microbiology, Microbiology Investigations, Microbiology Risk, Mould/Mold, Yeasts

Research – Report on the equivalence between the disinfection of tools in slaughterhouses and cutting rooms with hot water, at a temperature not lower than 82 °C, and various alternative disinfection systems.

Posted on March 19, 2022 by | Leave a comment

AESAN

The different tools and utensils used in slaughterhouses and cutting rooms may lead to cross contamination if unsuitable cleaning and disinfecting procedures are used. In this regard, Regulation (EC) No. 853/2004 laying down specific hygiene rules for food of animal origin establishes that slaughterhouses and cutting rooms for ungulates as well as poultry and lagomorphs must have facilities for disinfecting

The Scientific Committee of the Spanish Agency for Food Safety and Nutrition (AESAN) has assessed several studies carried out in order to establish whether disinfection with four alternative systems may be considered equivalent to that conducted with water supplied at a temperature not less than 82 ºC.
After reviewing the studies, the AESAN Scientific Committee concludes that a notable effort has been made to demonstrate the equivalence of these systems. It is observed in these studies that the use of these compounds leads to reductions in the microorganisms studied which, under the testing conditions, appear to be similar to those obtained with the official method.
However, these studies have methodological limitations (number of repetitions, sampling plan, the microorganisms studied and method of analysis) which prevent establishing this equivalence.
Accordingly, the Committee makes a series of recommendations for conducting these studies: using swabs instead of contact slides; including the analysis of foodborne pathogenic microorganisms of interest in slaughterhouses; including detailed information on the disinfecting products used as well as the method of analysis; harmonising sampling and analysis procedures; guaranteeing the representativeness of the samples taken (it is suggested to take 5 samples per slaughterhouse per day-taken from at least 4 different locations-, using 4 different slaughterhouses in the study, during 5 non-consecutive days, uniformly distributed over a period of 3 months; that is to say, a total of 100 samples); ensuring that all samples analysed are acceptable based on the established criteria for mesophilic aerobes (0-10 cfu/cm2), enterobacteria (0-1 cfu/cm2), as well as the absence/cm2 for the pathogens Listeria monocytogenes and Salmonella.
Likewise, it is also recommended to draw up a sector-based Guide that, based on the recommendations made in this report, provides a detailed description of the protocol to be followed in order to demonstrate equivalence between the disinfection of tools in slaughterhouses and cutting rooms with hot water supplied at a temperature not less than 82 ºC and disinfection with alternative methods.

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Posted in cross contamination, Decontamination Microbial, Enterobacteriaceae, Food Micro Blog, Food Microbiology, Food Microbiology Blog, Food Microbiology Research, Food Microbiology Testing, Listeria monocytogenes, Mesophilic Aerobes, microbial contamination, Microbiological Risk Assessment, Microbiology, Microbiology Investigations, Research, Salmonella