Spearmint (Mentha spicata L.) and Horsemint (Mentha longifolia L.) have abundant use in food expenses and Iranian Traditional Medicine. Tha aerial parts of both plants were collected and essential oil was isolated by hydrodistillation method (Clevenger). The extraction was conducted by maceration method (aqueous, hydroalcoholic and ethanolic solvents) and soxhlet method (ethanolic solvent). Total phenolic compounds content, Total flavonoid content, antioxidant capacity and free radical inhibition were measured. The results showed that total phenolic compounds and flavonoid content, total antioxidant capacity and percentage of free radical inhibition in applied extraction methods was different (P<0.05). The highest total phenolic compounds and flavonoid was obtained by soxhlet method in spearmint. The highest total antioxidant capacity were belong to hydroalcoholic extract in spearmint. Soxhlet extraction method is recommended because of its low processing cost, simplicity of operation, consume lesser time and solvent compared to other traditional methods such as soaking or percolation to extract phenolic compounds using other solvents. The use of a two-solvent system in the soaking process with other solvents requires further research to achieve high antioxidant properties.

In this study, the effect of hot oven drying condition (drying temperature and time) on weight loss, total phenolic compounds and antioxidant properties of mint leaf was investigated and optimized by response surface methodology. The results showed that with increasing drying time and temperature, weight loss and total phenolic compounds of mint leaves increased and drying time had more effect on changes of these two parameters compared to drying temperature. Total phenolic compounds of samples increased with increasing drying time, but with increasing drying temperature at the beginning of the process, the amount of total phenolic compounds of samples increased. The DPPH radical scavenging activity of the samples decreased by increasing the drying time (up to 176 min) and then increased with increasing the drying time. The results showed that applying drying temperatures up to 50 °C increased DPPH scavenging activity and higher drying temperatures resulted in a decrease in DPPH scavenging activity of the samples. Increasing the drying time and temperature reduced the antioxidant capacity and ferric reducing power (FRAP) of the samples, which the slope of the changes in the FRAP and antioxidant capacity of the samples with the changes in drying time is more severe than the drying temperature changes. The best conditions for hot oven drying of mint leaves are using drying temprature of 59.91 °C for 52 minutes and by applying the optimal conditions, the amount of weight loss, total phenolic compounds, and DPPH scavenging percentage of produced dry mint were 69.98%, 6.90 mg/gram of dry weight, 89.68% respectively and the desirability of this optimal condition was 0.746. The results of optimal conditions validation in real conditions are very similar to the results related to the predicted optimal conditions by response surface methodology.

Food industry produces a large amount of onion skin wastes. Due to the high amount of bioactive compounds found in such by-product, developing a method for the recovery of these biological lesions is important to benefit from them as a source of biologically active compounds.  The aims of this research were to compare the two methods, ultrasound and microwave, for extraction the phenolic compounds of red onion skin wastes and also to investigate the drying pre-treatment with conventional or infrared oven. The investigation the total phenolic compounds and anthocyanin content of extracts showed that use of ultrasonic method caused significantly (p < 0.05) enhanced extraction efficacy of phenolic compounds and anthocyanins. Additionally, drying by infrared oven caused significantly (p < 0.05) increase in total phenolic compounds and anthocyanins extraction. The antioxidant activity analysis of extracts showed that antioxidant capacity of samples extracted by ultrasonic method were significantly (p < 0.05) higher than that extracted by microwave method. As a result, the ultrasonic extraction by pretreatment applying infrared oven may be recomended as a suitable technique to extract phenolic compounds found in red onion skins to benefit from the nutritional potential of these biological wastes.

In this study, the effect of infrared drying process condition (drying temperature and time) on weight loss, total phenolic compounds and antioxidant properties of mint leaf was investigated and optimized by response surface methodology. The results showed that with increasing drying temperature, the weight loss of mint samples decreased, but with increasing drying time up to 176 minutes, the weight loss of the samples increased and then decreased. Drying time had a greater effect on weight loss changes in samples compared to drying temperature. The trend of changes in total phenolic compounds of samples with drying time was similar to the weight loss of samples, but with increasing drying temperature, the amount of total phenolic compounds of samples increased. The DPPH radical scavenging ability of the samples decreased with increasing drying time (up to 238 minutes) and then increased with increasing drying time. The results showed that applying drying temperatures up to 55°C increased DPPH radical scavenging ability of samples but applying higher drying temperatures led to a decrease in DPPH radical inhibition ability of the samples. Increasing the drying temperature increased the total antioxidant capacity and reduced the ferric reducing activity of the samples. Also, increasing the infrared drying time led to a decrease in the total antioxidant capacity of the samples. The best conditions for infrared drying of mint leaves are using drying temprature of 56.58 °C for 52 minutes and by applying the optimal conditions, the amount of weight loss (moisture loss), total phenolic compounds, and DPPH inhibition percentage of produced dry mint were 76.62%, 8.722 mg/gram of dry weight, 91.97% respectively and the desirability of this optimal condition was 0.727.

The aim of this research was to optimize the formulation of a functional drink based on sugarcane juice using the response surface method (RSM) and in the form of Box Benken design. The ingredients used in the formulation were lemon juice (0.3, 6), turmeric (0.6, 0.3) and mint extract (0, 250, 500) in percentage and their physicochemical properties (pH, acidity, soluble solids, turbidity, color, total phenolic compounds, antioxidant activity) and sensory characteristics were investigated. The results showed that increasing the amount of lemon juice increased acidity, turbidity, L index, b index, phenolic compounds, antioxidant capacity and overall acceptance, but decreased pH, soluble solids and a index. The increase of turmeric caused a slight increase in the amount of soluble solids, b index and total phenolic compounds, while it decreased the antioxidant property and overall acceptance of the samples. With the increase in the amount of mint extract, turbidity, a and b indices, phenolic compounds and overall acceptance increased, but the amount of soluble solids and L index decreased. Finally, the optimization results showed that the sugarcane juice drink containing lemon juice (6%), turmeric (0.2%) and mint extract (418%) had the best physicochemical properties and the highest overall acceptance and can be recommended as a healthy drink in the industry.

In the present study, the extract containing bioactive compounds from marigold (Calendula officinalis L.) medicinal plant was extracted using water, ethanol, acetone, ethanol/water and acetone/water as solvent. Among the solvents studied, the ethanolic extract contained the highest total phenolic compounds. The effect of the solvent to raw material ratio (40:1-10:1 mL/g) and particle size (0.5-2.36 mm) on the quantitative and qualitative properties of ethanolic extract at ambient temperature (25°C) were investigated. Based on the results, the highest crude extraction yield and total phenolic compounds equal to 3.5 ± 0.17% and 36.94 ± 0.81 mg GAE/gram of sample was obtained using a ratio of 30:1 mL/g and a particle size of 1 mm at ambient temperature. At the concentration of 1 mg/ml, the antioxidant activity of the extract was 62.95 ± 2.68 % and 153.18 ± 1.20 μΜ Fe2+/L, respectively. The high correlation coefficient (R2>09594) between total phenolic compounds and antioxidant activity indicates the key role of phenolic compounds in antioxidant activity. Finally, the ethanolic extract obtained from C. officinalis under mentioned conditions can be introduced as a natural source of phenolic antioxidants for application in the food and nutraceutical industry as a natural preservative.