Ultrasound-Assisted Coupled with Resin-Based Purification for Sustainable Extraction of Steviosides from Stevia rebaudiana Leaves

Stevioside, a natural high-intensity sweetener, is widely employed across the food, pharmaceutical, and daily chemical industries due to its intense sweetness and health benefits. However, traditional extraction and purification processes for steviol glycosides from <i>Stevia rebaudiana</i> are plagued by low efficiency, high energy consumption, substantial environmental impact, and inconsistent product quality. This study systematically optimized the extraction, decolorization, decontamination, and desalting processes to overcome these challenges. The extraction method was refined using 20% ethanol as the solvent, an optimal temperature of 50 °C, and a 1:10 material-to-liquid ratio, increasing the steviol glycoside yield from 32.0% to 49.1%. Decolorization employing a combination of resins D940 and T5 achieved decolorization rates of 89-92% with minimized steviol glycoside loss, surpassing the non-selective adsorption limitations of activated carbon. For decontamination, calcium hydroxide (Ca(OH)₂) outperformed diatomaceous earth, attaining a 98% protein removal rate while maintaining steviol glycoside loss below 20%. The desalting resin LXP-016 demonstrated superior performance at 40 °C, enhancing the ability of ionic impurity removal. These optimizations collectively improve the efficiency, sustainability, and quality of steviol glycoside production, offering a promising framework for industrial-scale applications.