Supercritical CO2 extraction and online fractionation of dry ginger for production of high-quality volatile oil and gingerols enriched oleoresin

Abstract

Ginger oleoresin and volatile oil find a wide range of applications in food, beverage, pharmaceutical, fragrance and biotech industry. The extraction and processing methodologies chosen are critical for the overall quality of the extract as well as for quantitative measure of temperature sensitive major actives present in the extract. In this context, a single step process for supercritical CO2 (SCCO2) extraction coupled with fractionation of dry ginger for simultaneous production of gingerols rich oleoresin and volatile oil has been proposed for the first time. The optimization and scale-up validation of this process have been achieved in three stages. Firstly, SCCO2 extraction conditions were optimized for the highest yield of mixture extract containing a maximum amount of volatile oil components and major actives [sum of (6 + 8+10) gingerols and 6-shogaol]. The optimum process variables under laboratory scale conditions were: average ginger particle size 253 μm, extraction temperature 40 °C, pressure 276 bar, flow rate 30 g min−1 and 153 min of extraction time. This resulted in 8.6% yield of a mixture extract having 37.97 wt % of major actives and 28.3 wt % of volatile oil. In the second stage of experiments, these conditions were scaled up 50 folds on a commercial scale unit. The recovered mixture extract recorded an improvement in 0.1% yield with an increase of 0.34 and 1.2 wt % in its major actives and volatile oil, respectively. Finally, the optimum conditions of online SCCO2 fractionation (coupled with same optimum extraction conditions) resulted in a 5.95% oleoresin yield, which was 96.15% pure and had 51.2 wt % of major actives, in separator 1 operating at 175 bar/40 °C. Simultaneously, 2.71% yield of volatile oil (95.94% pure) was recovered in separator 2 (40 bar/40 °C). The yield and quality of oleoresin and volatile oil extracted from conventional methods were also compared.