Optimization of extraction time and temperature for natural antioxidants of okuzgozu grape pomace using various solvent ratios

Abstract

Grape pomace, a press residue of winemaking process, has great usage potential in many fields because of its phenolic components such as anthocyanins, antioxidants and dietary fiber. In this study, it was aimed to determine most suitable parameters for production of food colorant from grape pomace (variety of okuzgozu) under different extraction conditions, thus utilising waste of wine production. The dried grape pomace was extracted at 3 various temperatures, 4 different periods and 5 different solvent ratios. 12 different anthocyanins, the free radical scavenging activity, total phenolic content and total monomeric anthocyanin of the extracts were determined and values of the samples ranged between 5.2-676.1 (mg/kg), 1.99-3.65 (IC50 mg/mL), 83.68-1598.57 (mg gallic acid/100 g) and 730.7-1850.3 (mg/100 gas mv-3-glc equivalents), respectively. The most suitable temperature, time and solvent ratio for the highest extraction of anthocyanins were obtained at 50 degrees C and 50:50, 180 min, respectively.