مجله میکروبیولوژی کاربردی در صنایع غذایی
سال نهم شماره 2 (تابستان 1402)

Jar cheese is a hard, slightly acidic and sweet pungent that has a granular state and has a dry appearance. In this study, the effect of relative substitution of NaCl salt with KCl (0.25, 50 and 75%) on the characteristics of free fatty acids, fat, peroxide and acidity of Jar cheese was investigated. The results showed that replacing NaCl with KCl and ripening time (5, 45 and 90) did not have a significant effect on fat and peroxide levels (p> 0.05). The acidity content in different treatments did not change significantly with the replacement of NaCl with KCl, Acidity content was increased significantly during ripening period (p <0.05). The results of measurement of fatty acid profiles showed that butyric acid was detected in all treatments and its quantification was   in lowest amount within specific days of ripening period (5, 45 and 90). partial replacement of NaCl with KCl did not affect the free fatty acid profile except for stearic acid (C18), and also no significant changes were observed in total amount of free fatty acids measured among all treatments (p> 0.05). In terms of the overall acceptance sensory score, a significant difference was observed between the control treatment and the treatment containing (9% KCl + 3% NaCl) and the closest treatment to the control treatment in terms of the sensory score of flavor, texture, appearance and overall acceptance is the T1 treatment containing (3% KCl + 9% NaCl). In general, the results of this study showed that 50% NaCl can be substituted with KCl.

The pigment properties of native yeasts have been proven in biotechnology. The ability of pigment production and antioxidant properties of native yeast species are investigated in this research. Among the 26 wastewater of food samples, five yeast isolates were identified in the stages of sampling and biochemical, microscopic, and macroscopic diagnostic tests. The ability to produce pigment and its antioxidant properties were investigated by DPPH, TEAC, and IC50 methods in the samples. Compared with the standard strain, the selected strains were identified using the PCR method and phylogeny tree drawing using MEGA7 software. Based on the results, the better 3 isolates were isolate No.1 (Rhodotorula sp. EY12114 (LC229721.1)), isolate No.2 (Rhodotorula mucilaginosa OMA Y14 (KR2649021)) and isolate No.5 (Rhodotorula mucilaginosa ITS1 (MG0206871)). The highest amount of pigment production was related to isolate No.5 (39.028 PPM), compared to the standard sample Rhodotorula glutinis PTCC5256 (47.731 PPM). Isolation and commercialization of indigenous species from factory effluents and optimizing the production of their biocompatible industrial metabolites such as pigments, which are used as antioxidants, permitted edible colors, and preservatives in the production of food products, not only have high-quality industrial efficiency but also It is very economical.

Macrolide antibiotics are important for the treatment of Campylobacter jejuni infections. Resistance to this class of antibiotics in Campylobacter is a complex process with dynamic molecular changes that are not well defined. In the present study, to fill the gap related to antibiotic resistance to Erythromycin treatment, the transcriptomic response of Campylobacter jejuni strain NCTC11168 to Erythromycin (ERY) treatment was determined by microarray method. The obtained data were identified, extracted and analyzed with GEO2R online tools and R software. Genes with the highest differential expression were identified by using parameters P<0.05 and LogFC |>1|. Then, the expression of the related genes was separated and for the genes that had an increase in expression, the protein network was predicted through the STRING database and visualized with the Cytoscape software. By identifying different genes that had a significant decrease or increase in expression, it was found that a set of flaA, flaB, flgB, CmeC, sdhA, sdhB genes can play a role in the antibiotic resistance of Campylobacter jejuni to the treatment with Erythromycin antibiotic. In this study by examining the goals, effectiveness and functional analysis of these genes, suitable solutions to curb the resistance were presented.

Today, the role of probiotics has been confirmed as beneficial microorganisms that play a role in improving health, preventing, and controlling host clinical disorders. According to the World Health Organization, if probiotics are prescribed to the host in sufficient and appropriate amounts, they can be very beneficial for health. In order to transfer the effects of probiotics to the consumer, it is necessary for probiotic microorganisms to be metabolically stable, active in food products, and able to survive in most parts of the digestive tract while also providing their beneficial effects in the host intestine. One major issue in this field is the ability of probiotic cells to survive physical and chemical attacks during their journey through the digestive system to the intestine. Recent advances have focused on improving micro-scale encapsulation techniques in order to achieve high cell viability, resistance to stomach acid, temperature resistance, and longer shelf life. However, these microencapsulation approaches still face limitations and challenges in terms of clinical translation. This present study offers a brief overview of the current progress of various probiotic encapsulation methods, with a particular emphasis on modern and emerging single cell encapsulation strategies that use nanocoatings for individual probiotic cells. Furthermore, the advantages of different nanoencapsulation methods are discussed, and future developments in coated probiotics with advanced properties and health benefits are anticipated.

The rate of spoilage and oxidation in fish and the change in color of fish tissue, its shelf life is limited; therefore, it is necessary to use natural antioxidants to delay, control or inhibit these adverse reactions and prevent the reduction of food quality. The current study was conducted to determine the effect of chitosan-based edible coating containing Dunaliella alga extract on preservation the quality of fresh Huso huso fillet during storage in refrigerator. Microbial and chemical tests including total bacterial load and saline bacteria, pH, TBA as well as sensory evaluation were performed periodically for all samples and for algae extract, antioxidant activity was measured by DPPH method. The total bacterial count on the 10th day of storage for samples coated with algae extract was 6.17±0.22 log CFU/g, which was in the acceptable range for human consumption, but in control samples was 9.41±0.20 log CFU/g on the 10th day, which is beyond the permissible limit. The amount of psychotropic bacteria for the control treatment significantly (p<0.05) increased compared to the chitosan-coated treatment containing the extract. The values of pH and TBA in the control sample were significantly higher compared to the treated sample on the 5th and 10th days of storage (p<0.05). This study showed that the growth of bacteria in fresh fish fillets can be prevented by using chitosan coating containing algae extract, and its sensory characteristics, including texture, smell, color, and general acceptability, have been preserved to a great extent and increased the period of keeping fish in the refrigerator.

Escherichia coli bacteria are often found in the human digestive system. The purpose of this research is to investigate the effect of probiotic mixture (Lactobacillus rhamnosus, Lactobacillus casei and Lactobacillus heloticus) on the damage of the small intestine tissue of male rats infected with Escherichia coli bacteria. In this experimental study, 21 adult male Wistar rats were divided into three groups of seven: control, infected with Escherichia coli bacteria (108 CFU/ml), and treated with probiotic mixture. Escherichia coli and probiotics (109 CFU/ml) were given to rats by gavage method. At the end of the experiment, the rats were euthanized, then tissue sections were prepared from the small intestine, the samples were stained by hematoxylin-eosin method and studied by light microscope. Small intestinal tissue damage showed a significant decrease in the probiotic treatment group compared to the bacteria-infected group (P<0.05). According to the findings of this research, probiotics can probably be used as a new application in a wide range of pharmaceutical products for the purposes of prevention or improvement of treatment methods.