Biosynthesis, characterization and antimicrobial activities of zinc oxide nanoparticles from leaf extract of Mentha pulegium (L.).

The synthesis of metal and semiconductor nanoparticles is an expanding research area due to the potential applications in the development of novel technologies. In the present study, a simple and eco-friendly synthesis of zinc oxide nanoparticles (ZnO NPs) using leaf extract of Mentha pulegium L. has been used. The biosynthesized ZnO NPs were characterized various techniques such as UV-Vis absorption spectroscopy, X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), Transmission electron microscopy (TEM), energy dispersive X-ray analysis (EDX) and Fourier transform infrared spectroscopy (FT-IR). The XRD data showed the crystalline nature of the nanoparticles and EDX measurements indicated the high zinc content of 56.26% and also oxygen with 43.74%. FT-IR confirmed the presence of functional groups of both leaf extract and ZnO NPs. The particles size and morphology determined from FE-SEM and TEM and UV visible absorbance spectrum of ZnO NPs exhibited the absorbance band at 370 nm. The synthesized ZnO nanoparticles as potential antibacterial agent has been studied on Escherichia coli and Staphylococcus aureus. These results indicate that aqueous extract of Mentha pulegium (L.) are effective reducing agents for green synthesis of ZnO NPs with significant antimicrobial potential.

Effect of goat lipase on sensory properties of curd / Efeito da lipase de cabra nas propriedades sensoriais da coalhada

Curd is one the main dairy products in Iran with high nutritional value. People tend to consume traditional products with special taste and odour and this has led industrial manufacturers to use some additives to adopt the sensory properties similar to traditional ones. Animal lipase is a good choice with three sources including calve, lamb and kid ones which create perfect taste and aroma. The aim of this study was to evaluate the effect of kid goat lipase at 5 levels (0, 50, 100, 150, 200 ppm) on some physic-chemical and sensory properties of curd in batch system. Results showed that addition of enzyme improved sensory properties and the highest score was gained in treatment containing 150 ppm of lipase.

A coalhada é um dos principais produtos lácteos no Irã com alto valor nutricional. As pessoas tendem a consumir produtos tradicionais com gosto e odor especiais e isso levou os fabricantes industriais a usar alguns aditivos para adotar as propriedades sensoriais semelhantes às tradicionais. A lipase animal é uma boa escolha com três fontes, incluindo bezerro, cordeiro e cabrito que criam sabor e aroma perfeitos. O objetivo deste estudo foi avaliar o efeito da lipase de cabrito em 5 níveis (0, 50, 100, 150, 200 ppm) em algumas propriedades físico-químicas e sensoriais da coalhada no sistema de lote. Os resultados mostraram que a adição de propriedades sensoriais melhoradas enzimáticas e a maior pontuação foi obtida no tratamento contendo 150 ppm de lipase.

Antifungal activity of essential oil of Ziziphora clinopodioides and the inhibition of aflatoxin B1 production in maize grain.

The aim of this study was to determine the antifungal effect of the essential oil obtained from Ziziphora clinopodioides L on two fungi species including Aspergillus flavus and Aspergillus parasiticus using microdilution method. The minimum inhibitory concentration (MIC) and minimum fungicidal concentration (MFC) were determined for the essential oil at 10 different concentrations (i.e. 25,000, 12,500, 6250, 3125, 1562.5, 781.25, 390.625, 195.31, 97.65, and 48.82 µg/ml). Finally, the effect of the essential oil at six levels (6250, 3125, 1600, 800, 400, and 196 µg/ml) was investigated on the growth and activity of A. flavus and A. parasiticus, and also toxin production of these species in maize at 0.97 aw and 25°C after 29 days. Aflatoxin B1 (AFB1) content was assayed by enzyme linked immuno-sorbent assay technique. Results showed that essential oil of Z. clinopodioides was found more effective on A. parasiticus than A. flavus in both in vitro and in vivo conditions. Z. clinopodioides oil exhibited the same MIC value in the liquid medium against all fungal strains (48.82 µg/ml), while it showed different activity against A. flavus and A. parasiticus with MFC values of 781.25 and 390.625 µg/ml respectively. Under storage condition in maize, AFB1 production was significantly (p < 0.05) repressed at the concentration of 6250 µg/ml for A. flavus and 6250 and 3125 µg/ml for A. parasiticus. At the lower concentrations, the AFB1 production increased gradually. The results of the present study indicated that the essential oil of Z. clinopodioides had significant antifungal activity (p < 0.05); therefore, it can be used as an antifungal agent in the food and medicinal industries.

Reduction of aflatoxin in rice by different cooking methods.

Rice (Oryza sativa Linn) is one of the basic diets in the north of Iran. The aim of present study was to detect total aflatoxin (AFT) in domestic and imported rice in Amol (in the north of Iran) and to evaluate the effect of different cooking methods on the levels of the toxin. For this purpose, 42 rice samples were collected from retail stores. The raw samples were analysed by enzyme-linked immunosorbent assay (ELISA) technique for toxin assessment and then submitted to two different cooking methods including traditional local method and in rice cooker. After treatment, AFT was determined. Results show that the average concentration of AFT in domestic and imported samples was 1.08 ± 0.02 and 1.89 ± 0.87 ppb, respectively, which is lower than national and European Union standards. The highest AFT reduction (24.8%) was observed when rice samples were cooked by rice cooker but the difference with local method was not statistically significant (p > 0.05).