a. haseli

Due to the richness of nutrients, especially at ambient temperature, doogh is prone to contamination with some microorganisms, which causes changes in the product flavor and its bloating during storage. Therefore, the use of natural antimicrobials such as Nepeta crispa exract to increase doogh shelf life while increasing its marketability can be important. The aim of this research was to investigate the effect of Nepeta crispa alcoholic extract on the qualitative properties of doogh. The compounds of Nepeta crispa extract were identified using GC-MS. Antioxidant activity, physicochemical (pH, acidity and viscosity), microbial (Escherichia coli and Staphylococcus aureus count) and sensory (taste, odour, texture and overall acceptance) characteristics of doogh containing different concentrations of Nepeta crispa extract (1.25, 2.5 and 5 mg/ml) were investigated during storage. ANOVA and Duncan test were used for statistical analysis. Thymol (53%) was the most identified compound in the extract of Nepeta crispa. The MIC of Nepeta crispa extract against E.coli and S.aureus was 2.5 and 1.5 mg/ml, respectively. The MBC of the extract against E.coli and S.aureus was 5 and 3 mg/ml, respectively. During storage, by adding plant extract, the acidity and viscosity of the samples increased and the pH decreased. Increasing the concentration of the extract increased the antioxidant and antimicrobial activity of doogh. The sample containing 2.5 mg/ml extract had the highest overall acceptance score, therefore, this sample was selected as the best treatment. Nepeta crispa extract has antimicrobial and antioxidant activities and might be used as a natural preservative in doogh.

Application of gums-based edible coatings to food products before frying is a technique that can improve the nutritional quality and sensory parameters of fried products. In this study, the effect of wild sage seed mucilage (WSSM) concentration at three concentrations of 0.5, 1.0 and 1.5% as edible coatings and frying temperature at three degrees of 155°C, 170°C and 185°C on the oil uptake and color change kinetics of zucchini slices during frying process have been studied. The color indexes include a* (redness), b* (yellowness), L* (lightness), and color change intensity (ΔE) were used to calculate appearance changes of fried zucchini slices. WSSM Coating treatments decreased the oil uptake of fried zucchini slices about 21.80%. By increasing WSSM concentration from 0.0% to 1.5% significantly decreased the oil uptake of zucchini slices from 8.96% to 7% (P<0.05), while the moisture content of samples were increased from 83.97% to 86.18% with increasing gum concentration (P<0.05). The average ΔE index of fried zucchini slices increased from 30.45 to 65.63 with increasing frying temperature from 155°C to 185°C. The average surface change values of fried zucchini slices was 33.13% for the uncoated samples, in comparison 30.40%, 29.36%, and 27.97% were found for fried slices coated with 0.5, 1.0 and 1.5% WSSM, respectively. The best coating suspension and temperature frying for reducing the oil uptake of fried zucchini slices was 1.5% WSSM and 155°C, respectively.