Pullulan gum production from low-quality fig syrup using Aureobasidium pullulans

Pullulan is an important polysaccharide with several potential applications in food science, pharmaceutical and cosmetic industries, but high costs of pullulan production are the main limitation for commercial utilization. Therefore, a cost-effective process for pullulan production was developed using fig syrup as an exclusive nutrient source. In particular, the feasibility of using low quality fig syrup as a supplemental substrate for pullulan gum production by Aureobasidium pullulans was investigated. Fermentation was carried out over a range of fig syrup and sucrose degrees Brix (5-15%). Maximum pullulan gum production was observed after 96h using 12.5% fig syrup, yielding approximately14.06 g/L. This value of pullulan production (14.06 g/L) was higher than the amount of pullulan produced using sucrose as substrate (5.01 g/L). In conclusion, fig syrup was an effective substrate for pullulan production by Aureobasidium pullulans, and, therefore, this byproduct deserves attention for the cost-effective and environmentally friendly pullulan production

Antibacterial activity of some Lamiaceae species against Staphylococcus aureus in yoghurt-based drink (Doogh)

Doogh is a dairy drinkable fermented product, whose shelf-life and quality is mostly affected by bacteria such as Staphylococcus spp. This study investigated the antibacterial activity of essential oils (EOs) from Thymus vulgaris L., Mentha piperita L. and Ziziphora tenuior L., alone or in combination, against Staphylococcus aureus in industrial doogh. A three-level and three-variable face centered central composite design experiment was used. Results showed that EOs significantly inhibited S. aureus growth after 1 and 7 days of storage. According to the model, the maximum inhibition was obtained in the presence of 0.2% of EO, independently of the type, and no synergistic or additive effects were observed. Slightly lower S. aureus survivals were observed at the maximum concentration of Z. tenuior EO. In spite of the antimicrobial activity of these EOs, further research is needed to assess their performance in food matrix and, in particular, in dairy product

Differences in the drought stress response of DREB2 and CAT1 genes and evaluation of related physiological parameters in some bread wheat cultivars

Abiotic stresses such as drought are among the most significant environmental stress causes in economically important crop plants including wheat (Triticum aestivum L.) and improving their yield is a major goal of plant breeding. In this study, we analysed expression of dehydration responsive element binding factor (DREB2), and an important antioxidant enzyme gene CAT1 in flag leaf of three bread wheat cultivars named Kavir, Kalheydari and Shahpasand under drought stress by RT-qPCR. In another section, physiological parameters including catalase enzyme (EC 1.11.1.6), relative water content (RWC) and chlorophyll content (a,b and total) were analysed. The cultivars were planted in a randomized complete block design with three replicates in normal and drought stress conditions on experimental field in 2013. Differential expression patterns of the genes DREB2 and CAT1 were observed in cultivars. The observed trend was the high induction in the expression of genes under drought stress. The expression of DREB2 was more than CAT1 in drought stress. The relative genes expression showed significant correlation with the catalase, RWC and chlorophyll b. Under drought stress, Kavir had higher expression of DREB2 and CAT1, activity of catalase, RWC, chlorophyll content (a, b and total) than the other cultivars. According to increasing of drought tolerance through the expression of these genes, it can be concluded that transferring of these genes may enhance drought tolerance in high-yield wheat cultivars

Novel strategies to control ethylene in fruit and vegetables for extending their shelf life : a review

Environmental factors in particular temperature, humidity, and atmosphere of packaging can control the postharvest physiology and variations in the chemical composition of horticultural crops during storage. Most fruits and vegetables release ethylene, as one of the simplest phyto-hormones, after harvest. Ethylene initiates ripening, produces softening and degradation of chlorophylls, and ultimately causing deterioration of fresh commodities. There are different methods to reduce ethylene production or inhibit its action to retain fruit and vegetable quality and extend their shelf life. Therefore, ethylene action can be limited at the receptor level (for example 1-MCP and Selenium), or through an effective elimination of released ethylene in the atmosphere. Among the emerging technologies, incorporation of nanoparticles into polymer matrix plays a major role in reducing the permeability of gases as well as absorption of ethylene. Accordingly, the present article reviews the characteristics, application types and effectiveness of ethylene control strategies for perishable commodities and their future aspects

Antifungal activities of coating incorporated with Saccharomyces cerevisiae cell wall mannoprotein on Aspergillus flavus growth and aflatoxin production in pistachio (Pistacia vera L.)

In this study, the effects of the mannoprotein isolated from Saccharomyces cerevisiae (ScMnn) were evaluated against Aspergillus flavus growth and aflatoxin (AF) production in pistachios. The mannoprotein extracted from the cell wall of S. cerevisiae was incorporated in gelatin-based solution at different concentration (0, 0.5, 1 and 1.5% w/w) then used as coating of kernels. A. flavus spore suspension (10 4 spores/mL) was inoculated on both coated (cp) and non-coated (ncp) pistachios. In cp samples, the mycelium development was delayed and AF content decreased, compared with the ncp ones. Noteworthy, the coating containing 1.5% ScMnn decreased AFB1 up to 42.81%. The ScMnn could be considered as an operative agent to reduce A. flavus growth and AF contamination in pistachios. The edible and food grade properties are important in its application as novel additive and as bioactive agent in coatings for the control of AF in pistachios. Practical applications: Active edible coating containing Saccharomyces cerevisiae mannoprotein could be applied in pistachio industry to control Aspergillus flavus growth and reduce aflatoxin contamination. This antifungal coating could improve the safety of pistachio nuts