Extraction of anthocyanins from grape pomace by using supercritical carbon dioxide

Abstract

Red grape pomace contains many secondary metabolites including anthocyanins and phenolic acids which significantly contribute to its antioxidant capacity. Herein, anthocyanins were extracted from grape pomace by using supercritical carbon dioxide. Ethyl alcohol was used as cosolvent. The temperature and pressure were kept constant during the extraction (95°C and 100 bar). The total extraction time was 180 min. The total monomeric anthocyanin content (TMAC) and total antioxidant capacity (TAC) were analyzed by taking samples from the extract at the 30th, 60th, 90th, 120th, 150th, and 180th min. The TMAC of grape pomace is 1,932.1 mg/kg dry matter. The TMAC and TAC values at each time intervals were calculated to be 579.2, 406.1, 123.7, 52.8, 38.5, and 16.4 mg/kg dry matter and 177.3, 171.1, 90.6, 44.7, 19.6, and 10.0 mg Trolox/100 g dry matter, respectively. The extractable TMAC and TAC values gradually decreased with time. The cumulative total anthocyanin content and antioxidant capacity increased with time. Practical applications The extraction of bioactive compounds from food matrices by using novel technologies has recently become a major challenge for the food industry since cost effective measures should be adopted in order to maximize the efficiency and to achieve the highest possible quality with the minimum input. Supercritical carbon dioxide (SCCO2) extraction has been recognized as one of such methods and it aims to shorten the process time while inducing the possibly least environmental damage. This research may serve as a guide for the potential industrial applications owing to following reasons; the determination of the steady state during extraction is critical to terminating the extraction at this steady state point to save energy and labor costs. The optimization of the extraction time will surely assist the cost reduction of food colorants including anthocyanins, which are yielded by the SCCO2 extraction and used for the production of jams and muffins.