مجله میکروبیولوژی کاربردی در صنایع غذایی
سال چهارم شماره 2 (تابستان 1397)

Mastinehis one of the traditional nomadic dairy products of Iran. This product is made from heated dough. Then the dry shevid, persian shallot, cucumalongaand other vegetables were added and mixed well. Althoughthis product is rich in fiber, no probiotic product has been made so far, one of the reasons is that probiotic bacteria are susceptible to hot filling packaging. Therefore, in this study, Bacillus coagulans spore in the concentration of 10 log cfu/g was added to mastineh. The results of the tests showed that this bacterium reduced the acidity at the end of the storage period but did not affect the pH. Bacillus coagulans count decreased during the storage period, but Bc survival was higher than the recommended minimum limit of 6 log cfu/g during 28-day storage. Investigation of L* parameter in probiotic mastineh showed that this parameter decreased during storage time, but it wasconstant in control one. The a* parameter did not have a significant change in both types of mastinah during the storage period. Also, there was no significant difference between the control probiotic mastineh in the b* parameter. There were no significant differences were showed between the two samples in sensory evaluation and rheological parameters. The evaluation of free fatty acid profile also showed that the highest amount of fatty acids was related to palmitic acid, myristic acid, stearic acid and valeric acid. According to the results, the Bacillus coagulans can be used as a suitable probiotic in the mastineh.

Due to an increasing risk of chemical contamination upon the application of synthetic fungicides to postharvest fruits, essential oils and plant extracts are gaining increasing attentions. In this research, antimicrobial potential of four essential oil; Mentha piperita. LCuminum cyminum,Foeniculum vulgare Mill, Eucalyptus camaldulensis Lwith different concentrations of 2, 5, 10, 15, 20 μl / ml against Botrytis cinere were investigated in two methods; liquid and vapour phase. Essential oil was extracted by Celvenger apparatus and afterwards analyzed by GC/MS. The dominant components of cumin were cumin aldehyde (18.77%), o-cymene (11.64%) and ℽ-terpinene(33.23%). In liquid phase method, cumin essential oil showed the highest inhibitory, which at the concentration of 10 μl / ml caused 100% inhibitory of fungal growth. The main oil compounds of peppermint were L-menthone (47.06%), isomentone (12.88%), L-(-)-menthol, (6.28%), and pulegone (11.21%). In vapour phase method, peppermint had the highest inhibitory at 2 μl / ml with 100% inhibition. In all essential oils, with the increasing concentrations of essential oil in both direct and vapour phase applications, the inhibitory percent increased significantly compared to the control. Overall, the antifungal activity of the essential oils depends on the type of plant, concentration and the method of application.

In this study, acidification and proteolysis in reconstituted skim milk fermented using proteolytic lactic acid bacteria were investigated during fermentation and after 7 days of cold storage. Also, antibacterial activities of crude peptide extracts obtained from the fermented samples were evaluated. Lactobacillus delberueckii subsp. bulgaricusL. reuteri and Lactococcus lactis subsp. lactis were used as starter in single or co-culture. Lactococcus lactis subsp. lactis and lactobacillus reuteri showed the fastest and slowest acidification, respectively, and the co-cultures were intermediate. During fermentation, the highest proteolytic activity was found in single culture of Lactococcus lactis subsp. lactis and triple co-culture(peptide content of 1.30 and 1.35 mg/ml) which was followed by a reduction after 7d storage. Peptide content from Lactobacillus reuteri fermentation was not significantly different from that of acidified control milk (ACM). ACM showed no antibacterial activity at the tested concentrations (5-40 mg/ml), while all the fermented milk samples showed antibacterial activities against all five tested pathogens at 40 mg/ml. After fermentation (day 0), the minimum inhibitory concentration of the most of fermented samples was calculated as 20 mg/ml, except for that of triple co-culture-fermented milk which was 40 mg/ml. The antibacterial activity of peptide extracts after 7d storage were varying and starter culture dependent. In overall, in spite that proteolysis resulted in antibacterial activity in the product, no positive correlation was found between proteolytic activity and antibacterial activity.

Increasing awareness of the adverse effects of chemical preservatives on health has led to an increased tendency to use natural preservatives, especially herbal essential oils in pharmaceutical and food products. Carum copticum (Ajwain) and Foeniculum vulgare (Fennel) are among the aromatic medicinal plants that can be used in this regard. In this study, the agar diffusion method was used to evaluate and compare the antimicrobial effects of the herbal essential oils in question and the dilution method in the liquid medium was also used to determine the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC). The checkerboard assay was used to evaluate the interaction between the herbal essential oils of Ajwain and Fennel and to determine the fractional inhibitory concentration. The results showed that the MIC of Ajwain and Fennel herbal essential oils against Escherichia coli was 1562.5 μg/ml and 12500 μg/ml, respectively, and in the case of Clostridium sporogenes this value was 1562.5 μg/ml and 50000 μg /ml, respectively. Calculation of fractional inhibitory concentration (FIC index) indicated that there was no interaction between the herbal essential oils of two plants against both bacteria in question. In general, the absence of synergistic and antagonistic interactions between the Ajwain and Fennel herbal essential oils can be related to the identically-affected sites of these essential oils in Escherichia coli and Clostridium sporogenes. Also, the results obtained through the identification of herbal essential oils composition by GC/MS showed that the main components of Ajwain were Thymol (49.96%), p-cymane (22.73%) and γ-Terpinene (15.32%) and in case of Fennel these components were Trans-anethole (63.88%), Estragole (9.97%), limonene (7.65%) and fenchone (5.72%).

Nowadays, hydrocolloids are used in food technology widely, because of some functional properties like thickening, gelling properties and emulsion stability. β-glucan is a homo-polysaccharide with base of glucose that is attended late, because of its bioactive properties in food and pharmacy technologies as a thickener and emulsion stabilizer agent and a good fat replacer for producing low fat products, furthermore, through decreasing of cholesterol and blood sugar, anticancer and antiviral properties. β-glucan is find in cell wall of microorganisms and plants widely. One microorganism that named as a source of β–glucan, is cell wall of Kluyveromyces marxianus yeast. Whereas efficiency of β–glucan can be affected of extraction conditions, in this paper so optimum extraction conditions and purification of β–glucan from cell wall of Kluyveromyces marxianus yeast (PTCC: 5194) is done with use of response surface methodology under a central composite design with study the time of extraction (1-2 h, in autoclave conditions), enzyme concentration (0.5-1.5 % Protamex enzyme) and enzyming time (1-3 h). The results were showed that increasing time caused increase in β–glucan extraction efficiency. Enzyme at more than 1% and emzyming time more than 2 h had not significant effect (p

With increasing consumer awareness, demand for sugar-free products and also products containing probiotic bacteria has been increased in recent years. As a result, the formulation of a non-fermented product which can be a suitable carrier for probiotic bacteria, as well as reduced sugar intake, is of particular importance. The purpose of this study was to formulate and commercialize a kind of sugarless probiotic chocolate dessert containing date sugar. For this purpose, 17 treatments were prepared according to the experimental design (RSM: Response Surface Methodology) and were kept in the refrigerator until the tests were performed on days 1, 11 and 21. The results showed that probiotic viability decreased with increasing date sugar content and storage time, but did not reach to 107 cfu/g (p