Microbial Product Quality Research Articles

Microbial Fermentation and Shelf Life of Potential Biotechnological Products Capable of Pesticide Degradation

The pesticide active ingredient azoxystrobin is widely used in agriculture and has negative effects for the environment and contained organisms. Bacterial strains have been reported to degrade azoxystrobin, but precise methodologies for producing and storing these strains as potential biotechnological products are lacking. The study focused on creating and optimising a non-sterile, small-scale microbial fermentation protocol to produce azoxystrobin-degrading products and to test their shelf life. By testing 14 variants and sampling at three production and two storage time points, the trial demonstrated the successful production and storage of microbial products capable of pesticide degradation. Various measurement parameters such as pH value and organic acids were used to monitor the quality of the microbial products during the production and storage. Further, we developed and validated qPCR assays to rapidly and specifically assess the concentration of the two azoxystrobin degrading strains, namely Bacillus subtilis strain MK101 and Rhodococcus fascians strain MK144. To ensure good specificity, the combination of two qPCR assays targeting two different genome regions was implemented for each strain. The study highlights the significant impact of media selection and bacterial inoculum quantity on the microbial product quality.

Evaluation of Good Manufacturing Practices in Small Dairy Plants in Jordan

The aim of this study was to assess the good manufacturing practices (GMPs) in small dairy plants in Jordan. In addition, the microbial product quality was used to assess the quality control practices in the production of concentrated yogurt (Labanah). The study was applied to 40 small dairy plants in the governorates of Irbid and Jerash, north of Jordan. Data were collected using a questionnaire, which consisted of a general information section besides two sections that addressed GMPs and the barriers to implementation of GMPs in the small dairy plants in Jordan. Assessment of GMPs was performed by using a structured questionnaire (checklist) that consisted of four sub-sections that addressed contemplating building, personnel, equipment, and food production. The mean overall score of implementation of GMPs in Irbid was 2.75, meaning that implementation of GMPs was low to moderate, while in Jerash it was 2.14, suggesting a low level of implementation of GMPs. Results showed that poor infrastructure and lack of financial resources were the most prominent obstacles to implementation of GMPs in the sample dairy plants in both governorates. The mean total counts of bacteria in the Labanah samples collected from the 40 dairy plants were 4.36 and 6.8 log 10 cfu/mL, respectively. All the Labanah samples showed negative results of salmonella and staphyllocccus . Contamination of the Labanah samples with yeast and molds, and coliform bacteria was an indicator of insufficient hygienic practices. Implementation of the food safety practices by the dairy producers is necessary. Keywords: Food safety, Labanah, Microbiological quality. DOI : 10.7176/FSQM/84-05

Quality of fresh saithe (Pollachius virens) in modified atmosphere packages as affected by the gas composition

Abstract The experimental design was set up to study the effect of different modified atmospheres (CO2 (67 or 33%) balanced with either O2 or N2) on autolytic- and microbiological deterioration of chilled saithe (Pollachius virens). As controls, vacuum packaged saithe was used. The results showed a positive effect of gas mixtures containing O2 on physiochemical and microbial product quality. Discriminating factors were; lower psychrotrophic count, slower breakdown of ATP, lower contents of certain biogenic amines (e.g. cadaverine) and reduced drip loss during storage. A high CO2 concentration (67%) in the packaging atmosphere was moreover found to inhibit microbial proliferation. Vacuum-packaged saithe stand out negatively with highest DL and reduced sensory shelf life and physiochemical and microbial quality. It was moreover found that increased drip loss, and higher contents of hypoxanthine and cadaverine in the muscle tissue was related to the microbiological ecology (i.e. increased growth of Shewanella spp. and Photobacterium spp.).

Antimicrobial Activity of Whey Protein Isolate Edible Films with Essential Oils against Food Spoilers and Foodborne Pathogens

The use of antimicrobial edible film is proposed as a means of improving food safety and extending the shelf-life of food systems by controlling the release of antimicrobials on food surfaces. In this work we first selected and studied 8 different essential oils (EOs) from plants, namely, oregano, clove, tea tree, coriander, mastic thyme, laurel, rosemary, and sage as natural antimicrobials against 2 gram-positive bacteria (Listeria innocua and Staphylococcus aureus) and 2 gram-negative bacteria (Salmonella enteritidis and Pseudomona fragi) by using the agar disk diffusion method. EOs from oregano, clove, and tea tree produced the largest surfaces of inhibition against the growth of the 4 bacterial strains tested. Second and following the assessment of compatibility, stable antimicrobial edible films based on whey protein isolate (WPI) with increasing concentrations (0.5% to 9%) of the 8 EOs were developed and tested for antimicrobial activity against the same gram-positive and gram-negative bacteria. WPI-edible films incorporating oregano or clove EO were found to have the most intense inhibitory effect of microbial growth. The bacterial strain gram-negative P. fragi presented the less susceptibility to the effect of those films. Moreover, only the edible films based on these 2 EOs were active against all 4 studied microorganisms. On the other hand, the edible films incorporating tea tree, coriander, mastic thyme, laurel, rosemary, or sage EOs even at high concentrations (7% to 9%) did not cause any antimicrobial effect against the pathogens S. aureus or S. enteritidis. Potential applications of this technology can introduce direct benefits to the food industry by improving safety and microbial product quality. The results of this research have direct application in the food industry with potential applications in various foodstuffs, including meat and poultry products where the control of spoilage bacteria such as P. fragi throughout their chilled storage or the improvement of food safety by controlling pathogens such as S. enteritidis are topics of particular interest for the industry.