مجله میکروبیولوژی کاربردی در صنایع غذایی
سال ششم شماره 1 (بهار 1399)

In this study, two-layer extrusion method was performed on Lactobacillus reuteri. The first layer was sodium alginate and the second one basil seed mucilage in five concentrations (0.2, 0.4, 0.6, 0.8 and 1 percent). The image was provided from microencapsulated form to determine the diameter of the layers and microencapsulated color components L*, a*, b*, whiteness and yellowness. Thermal, salt, acid survivability, growth and acid production of free and microencapsulated bacteria in MRS medium were investigated. The results of this research showed that as increasing the percentage of mucilage gum used as the second layer can cause a significant change in the outer layer diameter. The b*, whiteness, and yellowness parameters increased but the L* parameter decreased significantly (p≤ 0.05). Microencapsulated containing 1 precent basil seed mucilage can survive for 5 min at 72 °C, above minimal probiotic concentration limited (6 log CFU/g) based on regression curve. But the free-living bacterium only survived for 0.6 min at this limited. As the basil seed mucilage concentration increased, the bacterial survivability was increased under salt and acidic conditions. The microcapsulated form survivability time (7.5 min) was greater than free form (2.5 min). The rate of acid production and bacterial growth in the microencapsulated form was slower than the free bacteria.

Pistachio is an important export product in Iran. This product is always damaged by various living and non-living agents. One of the diseases that cause damage to this pistachio tree in most areas of pistachio is gumosis disease caused by Phytophthora drescleri. Various methods have been proposed for the management of this disease such as the use of resistant cultivars, the use of biological control and changing soil environment conditions to make the conditions unfavorable for pathogen control. In this study, it was used the ammonium sulfate, potassium sulfate and triple superphosphate against gum disease. The results showed that the highest rate of growth reduction of pathogenic fungi was related to the concentration of 2500 ppm ammonium sulfate compound (67.16percent). In the greenhouse, the effects of different treatments including mycorrhizal fungi and ammonium sulfate alone and their combination in reducing disease caused by P. drescleri on growth traits such as plant height and leaf area were evaluated. In the other part of the study, the effects of these treatments on physiological traits such as total chlorophyll and antioxidant enzymes activities such as peroxidase, catalase and polyphenol oxidase were investigated. The results showed that treatment with mycorrhizal fungi and ammonium sulfate always had the highest height and leaf area among the treatments, with 25.53 cm2 and 81.19 cm2 respectively compared to healthy control with 82 cm cm, respectively 16.82 and 50.39 cm2). Regarding physiological characters as well as trace elements content, the most frequent treatment was the combination of mycorrhizal fungi and ammonium sulfate in both Bo cultivars for chlorophyll and catalase, peroxidase and polyphenyl oxidase enzymes. In the case of the two cultivars, Sarakhs and Almonds, because Sarakhs was more susceptible to Almonds, were always lower in all studied traits. The results showed that the use of mycorrhizal fungi as well as ammonium sulfate improved plant condition and plant resistance to pathogen. In the first part of the study, it was also shown that some nutrients in addition to the positive effect on the plant have a negative effect on the pathogen.

In the present study, the effect of incubation temperature (40 to 60 °C), fermentation time (48 to 72 hours), concentrations of permeate (5-10percent) and vinasse (0 to 15percent) as fermentation variable on the production and productivity of lactic acid were studied using a Box-Behnken design. The results showed that all four independent variables had a significant effect on lactic acid production (p 0.05). Optimization by the desirability function method showed that the maximum production of lactic acid by B. coagulance was at 41 °C, fermentation time of 63 hours, permeate and vinasse as fermentation medium was equal to 8.5 and 10percent (w/v). Thelactic acid production in these conditions was 10.23 g/L. Finally, an HPLC analysis was used to confirm the amount of lactic acid production.

The objective of this study was to evaluate the potential of three probiotic microorganisms Lactobacillus plantarumLactobacillus casei and Lactobacillus acidophilus to produce probiotic kiwifruit juices. For this purpose, kiwifruit juice was inoculated with 7 log cfu/ml of each microorganism and the changes in bacterial cell viability, physicochemical properties and sensory characteristics of the beverages were monitored during a 72-h fermentation period at 37 °C and a subsequent 4-week storage period at 5 °C. The results showed that the viability of all the strains was improved significantly over the fermentation period and reached a pick at the first week of the storage period; however, as the storage period prolonged, the viability of the microorganisms decreased steadily. Notwithstanding this, at the end of the storage period, the viable cell counts of L. delbrueckiiL. plantarum and L. acidophilus were 8.4, 8 and 7.1 log cfu/ml, respectively, which are higher than the minimum requirements of the probiotic status. The findings revealed that the pH, total sugar content and brix of all the beverages decreased steadily during both fermentation and storage periods whereas the acidity increased. The greatest changes in physicochemical properties were observed in the beverage containing L. plantarum, followed by the samples fermented with Lactobacillus casei and Lactobacillus acidophilus. Although the sensory acceptance of the probiotic beverages was significantly less than the control sample, they all received desirable sensory scores at the end of the storage period. In conclusion, it is possible to develop probiotics kiwifruit juice using each of the three microorganisms, although the results obtained for L. plantarum were more promising.

The Bacillus race is one of the most important producers of amylase in the last few decades due to its high ability to produce excess enzymes. Despite the fact that domestic research is ongoing, the production of this enzyme is not yet possible. Therefore, it is important to study and find an appropriate environment for producing this enzyme at the lowest cost and maximum efficiency.In this study, amylase production environments were provided with a source of carbonaceous molasses of sugar cane and whey with different concentrations and Bacillus lichen formis were cultured in each one. Following the drawing of the standard Bradford curve and Nitrosalicylic acid test, total protein and enzyme activity was evaluated every 24 hours.The results of total protein and amylase activity analysis from Bacillus licheniformis showed that the most productive and enzymatic activity was related to the sugar beet molasses medium at a concentration of 1/2 of the total environment at 50 ° C and after It is 72 hours after the cultivation. The amount of protein and enzyme activity in the whey was much less than that of the molasses. It can be concluded that the medium containing cane molasses can be a good environment for the production of amylase enzyme in the enzyme production industry.

Yeasts can be considered as the oldest industrial microorganisms used by humans. Yeast is an indispensable product for baking bread and is responsible for the desired fermentation of the dough and creating aroma and flavor in the bread.One of the effective factors in obtaining suitable yeast is providing the best drying conditions. Fluized bed drier is the most common methods for drying yeast. In this research, the effects of factors such as drying temperature, aeration and amount of surfactant that firstly were selected by Taguchi method as the most effective factors were investigated on the amount of CO2 released, moisture content and propagation of yeast alive by the RSM statistical design and eventually optimized. Based on the results, the best conditions for drying yeast by fluized bed at a temperature of about 39.8 °C, aeration of about 15600 m3 per hour, and surfactant 11.9 g/kg of yeast were determined by the Minitab software. In this condition was found to have the highest viability (78.8%), minimum moisture content (37.5%) and the highest CO2 production (1390 cc/2h) for yeast.