Optimization of process parameters for microwave assisted extraction of stevioside from <em>Stevia rebaudiana (Bertoni)</em> leaves

Abstract

Microwave assisted extraction process was employed for the extraction of stevioside from dry stevia leaf powder. The independent factors were leaf to water ratio (1:5 to 1:25), extraction time (0.5 to 2 min), and microwave power level (180 to 900 watt). The pooled effect of these independent factors on the stevioside content, color and TSS of the extract was studied. For optimizing the extraction process, box-behnken design in amalgamation with response surface methodology was employed. Significant regression models with coefficient of determination greater than 0.80 were established to evaluate the effect of independent factors on the responses. The optimum extraction conditions are: microwave power level: 454-watt, extraction time: 1.13 min and leaf to water ratio: 1:25 (g: mL). The maximum predicted values for stevioside content at optimum conditions was 9.37%.