مجله میکروبیولوژی کاربردی در صنایع غذایی
سال نهم شماره 1 (بهار 1402)

Due to the increasing awareness of human societies about the health-enhancing effects of synbiotic products, the production and consumption of these products has been growing. However, the majority of products, including beverages, in the global market are dairy-based, and less attention has been paid to the production and expansion of grain-based synbiotic foods. As a result, an attempt has been made in this study to present a synbiotic fermented beverage based on grains with practical and health-giving properties as well as consumer-friendly characteristics. To produce this beverage, alfalfa, millet, and rye sprout extracts were inoculated with Lactobacillus plantarum and Lactobacillus casei bacteria, and inulin and oligofructose (0, 1.5, and 3%) were used as prebiotics. The prepared formulations were stored at 4±1°C and on days 1, 7, 14, 21 and 28, their physicochemical properties (turbidity, sediment, etanol and phenolic compounds) were evaluated and the data were analyzed with SPSS software. The results show that the percentage of polyphenol decreased significantly with the presence of inulin, oligofructose, Lactobacillus casei, and Lactobacillus plantarum, but increased with storage time and the activity of Lactobacillus casei and Lactobacillus plantarum (p≥0.05). The addition of inulin and oligofructose in the drink, the passage of time, as well as the activity of Lactobacillus casei and Plantarum increased the percentage of turbidity (p≥0.05). It can be said that with the addition of inulin and oligofructose in beverages, the sedimentation percentage of beverages decreased (p≥0.05). Also, increasing the percentage of inulin and, in particular, oligofructose, storage time, as well as the activity of Lactobacillus casei and plantarum increase the percentage of ethanol (p≥0.05).

In this study, the antifungal effects of four species of plant essential oils, including Thymus vulgaris, Eucalyptus camaldulensis, Lavandula angustifolia and Cuminum cyminum, were studied on mycelial growth inhibition of F. oxysporum and F. culmorum isolates. The effect of essential oils was carried out in a factorial experiment in a completely randomized design with four concentrations for each essence and three replicates in 25 °C on PDA medium. The results showed that the essential oils of these plants has a significant effect on inhibition of the mentioned pathogenic isolates fungal mycelial growth. The required concentrations for the maximum mycelial growth inhibition of F. oxysporum isolate in 250 ppm for essential oils Cumin, Eucalyptus, Thyme and Lavender were 100, 96, 93 and 89 percent, and for F. culmorum isolates were 99, 96, 92 and 77, respectively. The minimum inhibitory concentrations of the cumin, Eucalyptus, thyme and lavender on F. oxysporum in 50 ppm were 48.8, 29.4, 44 and 38 respectively and for F. culmorum these concentrations were 38.8, 29.4, 44 and 18 percent respectively. The highest and lowest mycelial inhibitory growth was showed by cumin essence in 250 ppm and lavender and eucalyptus essences in 50 ppm, respectively. In all four essential oils, the growth of the fungi decreased by increasing the essential oil concentration. Regarding the antifungal and inhibitory effects of the essential oils of the plants and their low risk for humans and the environment, it seems that plant essence can be used to control plant pathogenic fungi or at least as substitution for the production of new fungicides.

Innovation in food production and processing is needed to respond to emerging challenges, ensure food security worldwide, and meet consumer demands for high-quality, safe, and nutritious food products. Plasma-activated water is an environmentally friendly technique with minimal changes in food products. Plasma-activated water has been receiving increasing attention for applications in food, agriculture and biomedical fields. In particular, this article specifies the physical and chemical properties of plasma-activated water in relation to acidity, conductivity, oxidation - reduction potential, and concentration of reactive oxygen species and reactive nitrogen in purified water. Therefore, the application methods of plasma-activated water for microbial disinfection are also have been summarized in this review. Overall, this review article describes the success achieved by plasma-activated water technology in various application methods; meanwhile, demonstrates its importance in the food processing industry. As the research output on plasma-activated water is expanding exponentially, this review focuses on literature published between the years 2017 to 2022 to summarize a current perception on the principles of plasma-activated water effects and reflect its potentials in various methods of application. Furthermore, prominent drawbacks of this technology was discussed, while important areas for future research were highlighted.

Pathogenic and non-pathogenic bacteria release membrane vesicles into the extracellular environment, but their activity is not known. The purpose of this research was to study the antibacterial activity of the extracellular vesicles of the probiotic Lactobacillus casei and its effect on increasing the shelf life of Otolites ruber fillet. Vesicles were isolated through ultracentrifugation protocol. Antibacterial activity of vesicles on Shewanella putrefaciens was studied. Then fish fillet 250-300 g was prepared. Each fillet was placed in 10 mL of solution prepared from different concentrations of vesicles (109, 1010, 1011 vesicles/ mL) until the solution was completely absorbed by the fillets, and then they were kept at 4 °C. The shelf life indices of the fillet included the amount of peroxide, total volatile nitrogen bases, malondialdehyde, and the Total Viable Count. The results showed that the size of vesicles increased significantly up to 48 h after incubation (P<0.05) and then the trend of changes was not significant (P>0.05). The amount of 1011 vesicles/ mL could inhibit the growth of S. putrefaciens. The results of the fillet quality showed that the dose of 1011 vesicles/ mL could improve the shelf life indices of the fillet and increase it by 4 days compared to the control group and lower doses. The results of this study showed that Lactobacillus casei-derived extracellular vesicles can be used to improve the quality of fish fillet.

In this research, Lactobacillus casei and Lactobacillus acidophilus bacteria were added to watercress drink and the physicochemical properties, antioxidant activity, viability of probiotic bacteria and sensory characteristics of the samples were investigated in the period of 1, 15 and 30 days after production. The results showed that the pH in all samples decreased significantly with time. Brix of the samples containing higher amounts of watercress was more, and with the passage of time, the turbidity of all samples decreased significantly. The samples containing higher amounts of watercress had higher total phenol and antioxidant activity, and with the passage of time, the IC50 of all samples increased significantly and their total phenol decreased significantly. On the 1st and 15th days, the highest viability rates of both microorganisms belonged to samples containing 75% watercress. Watercress extract helped the viability of Lactobacillus casei and Lactobacillus acidophilus with its antioxidant activity and significant phenolic compounds. The results of the sensory evaluation showed that there was no statistically significant difference in the score of flavor, aroma, texture, color and overall acceptability of the samples on all the days investigated.

Cold plasma is one of the ways to increase useful life in the food industry, which reduces pollution. The aim of this study was to investigate the increase in the shelf life of lemons prepared with cold plasma. The samples were subjected to cold plasma treatment using two gases (argon and air) for a period of 0, 5, 10 and 20 minutes on the surface of lime, which reduced yeast and copy italicum 1 to 99%. The results of microbial analyzes revealed that within five minutes under the plasma treatment of argon cold gases and  air, the microbial load reduced by 99% and had the least effect on the physical and appearance properties of the lime product. After applying the treatment, the samples were free of coliform and P. italicumon mold. Examining the physical properties of lime (texture and weight) showed that the effect of gas type had a significant effect on these indicators. The increase in plasma treatment time in six minutes and atmospheric pressure was significantly different (p<0.05). Examining the type of gas and its effect on the treatment showed that the type makes a significant difference and about ten percent of the effectiveness of argon gas is slightly higher than air. It will be a suitable and low-cost method for sterilizing and pasteurizing limes in order to preserve them.