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Stevia is a seasonal herb that contains high levels of phenolic and sugar compounds called stevioside rhabadiosid. Due to the seasonality of this plant, the most suitable method for making it available is using drying methods. Choosing the proper method of plant drying is one of the most important issues in post-harvest operation. Using inappropriate methods can result in the loss of plant organs or the loss of all the effective substances in it. The main objective of this study was to evaluate the effect of temperature and velocity of dryer on drying process, total phenolic compounds and kinetic modeling of stevia leaf drying. For this purpose, air temperature was measured at three levels (45 °C, 55 °C, 70 °C) and air velocity at three levels (0.5 m/s, 1 m/s and 1.5 m/s) for drying Stevia leaves were used. In this research, five models of Pelge math, Weibull, Logarithmic, Page and Khazaei models were used to model the results of stevia leaf drying process. The results showed that the proposed experimental models had a desirable performance in the modeling of the stevia moisture reduction process (R2 ≥ 0.945). By comparing the output values of R2 and Root Mean Square Error (RMSE) for the models presented, the Page model had better modeling performance than the other four models. In addition, the results showed that in the drying process, the most important factor in controlling the stevia leaf drying rate was the air temperature. Also, the drying time of stevia leaves decreased with increasing temperature and speed of air drying. Dryer temperature has a significant effect on the content of total phenolic compounds. As the air temperature raised from 45 °C to 70 °C, the amount of phenolic compounds of the stevia leaf decreased. The best air temperature and temperature was maintained to maintain the static fiber phenolic compounds at 45 °C and 1 m/s. [ABSTRACT FROM AUTHOR]

The aim of this study was to investigate the effect of probiotic bacteria and trypsin enzyme on the physicochemical, microbial and sensory properties of dough. For this purpose, bioactive peptides of 1.5 and 3 mg /100 ml were added to the probiotic dough formulation, which were inoculated separately with 108 cfu / ml of Lactobacillus acidophilus and Lactobacillus helveticus. PH tests, mold and yeast counts, coliform counting, probiotic bacterial survival, antioxidant activity evaluation, gamma amino butyric acid measurement and sensory evaluation were performed on dough. The results showed that the use of probiotic bacteria with trypsin enzyme and increasing its concentration was maintained viability increase, probiotic bacteria, antioxidant properties, GABA production rate, and sensory evaluation score after 60 days. It also reduced pH, mold and coliforms in dough. Using Lactobacillus acidophilus and the enzyme trypsin 3 mg / 100 ml can produce high-yielding dough containing GABA with lower microbial load and higher antioxidant and sensory properties. [ABSTRACT FROM AUTHOR]