DIC as a pretreatment prior to ultrasonic extraction for the improvement of rebaudioside A yield and preservation of vitamin B1 and B6

Abstract

Steviarebaudiana bertoni is a sweet herb known for its nutritional and therapeutic values and is recommended as a treatment against several diseases like diabetes. The purpose of this work was to intensify the ultra-sound assisted extraction of rebaudioside A and hydro-soluble vitamins from this plant by instant controlled pressure drop (DIC) swell drying with comparison to the classical drying method. Others extraction factors were also studied and the response surface methodology was used to test the model and to optimize extraction conditions. The different extracts were characterized by means of reversed phase HPLC and the yields of rebaudioside A, vitamin B1 and vitamin B6 were quantified. Results show a significant positive effect of DIC on the extraction of the three bio-molecules which allows minimizing solvent concentration, temperature and the ratio solvent/solute. The effect of DIC was nearly the same for rebaudioside A and vitamin B6 and more intense for vitamin B1. Optimum conditions for simultaneous extraction led to respectively 3.0 (g/100 g), 3.5 (mg/100 g) and 1.5 (mg/100 g) of rebaudioside A, thiamine and vitamin B6.