Optimization of extraction parameters of diterpene glycosides from stevia leaves by mathematical modeling

Abstract

The parameters and modes of extraction of stevioside – hydromodule, temperature and duration of the process were selected in the work. The object of the study was dried stevia leaves of the Ramon Sweetmeat variety. The determination of diterpene glycosides in the extract was carried out by the modified Komissarenko method. To optimize the technological parameters of extraction, regression models of the second order were built using orthogonal central composition planning. The degree of crushing of stevia leaves was 1-3 mm. The extraction at a temperature below 76 ° C reduces the amount of diterpene glycosides in the aqueous extract, and an increase in the extraction temperature above 92 ° C does not increase the yield of glycoside. The maximum extraction of diterpene glycosides is achieved at an extraction temperature of 92 ° C. When selecting a hydromodule, extraction was carried out at the ratio of stevia leaves and water 1:5, 1:10, 1:15. The highest yield of extractive substances was observed with a hydromodule of 1:10. With an increase in the duration of extraction from 60 to 180 minutes, an increase in the extract is observed. The optimal duration of the extraction process is 120 min. Based on the experimental data obtained, a second-order mathematical model was constructed, suitable for optimizing the process of obtaining stevia extract. The main factors influencing the process of stevioside transition from leaves to solution were considered: extraction temperature, °C; extraction duration, min; hydromodule. The criteria for evaluating the efficiency of the extraction process were: the yield of diterpene glycosides % by weight of stevia and energy consumption kW/dm3 extract. The first criterion is desirable to maximize, the second – to minimize. Optimal extraction modes are obtained:hydromodule - 1:10.8, temperature - 79.8 ° C, duration - 94.1 min.