A Hybrid RSM-ANN-GA Approach on Optimization of Ultrasound-Assisted Extraction Conditions for Bioactive Component-Rich Stevia rebaudiana (Bertoni) Leaves Extract

Stevia rebaudiana (Bertoni) leaves consist of dietetically important diterpene steviol glycosides (SGs): stevioside (ST) and rebaudioside-A (Reb-A). ST and Reb-A are key sweetening compounds exhibiting a sweetening potential of 100 to 300 times more intense than that of table sucrose. Ultrasound-assisted extraction (UAE) of SGs was optimized by effective process optimization techniques, such as response surface methodology (RSM) and artificial neural network (ANN) modeling coupled with genetic algorithm (GA) as a function of ethanol concentration (X-1: 0-100%), sonication time (X-2: 10-54 min), and leaf-solvent ratio (X-3: 0.148-0.313 g.mL(-1)). The maximum target responses were obtained at optimum UAE conditions of 75% (X-1), 43 min (X-2), and 0.28 g.mL(-1) (X-3). ANN-GA as a potential alternative indicated superiority to RSM. UAE as a green technology proved superior to conventional maceration extraction (CME) with reduced resource consumption. Moreover, UAE resulted in a higher total extract yield (TEY) and SGs including Reb-A and ST yields as compared to those that were obtained by CME with a marked reduction in resource consumption and CO2 emission. The findings of the present study evidenced the significance of UAE as an ecofriendly extraction method for extracting SGs, and UAE scale-up could be employed for effectiveness on an industrial scale. These findings evidenced that the UAE is a high-efficiency extraction method with an improved statistical approach.

Automated summary

This study optimized the ultrasound-assisted extraction (UAE) of dietetically important diterpene steviol glycosides (SGs) from Stevia rebaudiana leaves. The results showed that UAE, under the optimized conditions of ethanol concentration, sonication time, and leaf-solvent ratio, achieved the highest extract yield. UAE was found to be superior to conventional maceration extraction (CME) in terms of resource consumption, total extract yield (TEY), and SG yields. The findings support the use of UAE as an ecofriendly and efficient extraction method for industrial scale-up.