Alteration of Antioxidant Activity and Total Phenolic Content during the Eight-Week Fermentation of Apple Cider Vinegar

Abstract

Apple is one of the delicious fruit consumed by people. Apple cider vinegar was made through the traditional method and the changes occurred during the 8 week fermentation period were determined in this research. Total titratable acidity, pH, total soluble solids (°brix), total phenolic contents, Oxygen Radical Absorbance Capacity (ORAC) and Trolox Equivalent Antioxidant Capacity (TEAC) assays, phenolic contents were determined. Total phenolic substance, ORAC and TEAC values increased significantly weekly and reached the highest level in the 3rd week. Total phenolic substance, ORAC and TEAC values of 3rd week apple vinegar were determined as 1110.63 mg GAE L-1, 10.92 mM and 21.11 µmol TE mL-1, respectively. Apple vinegar samples had gallic acid, catechin, epicatechin, chlorogenic acid, and p-coumaric acid. The major phenolic substances in apple vinegar were gallic acid and chlorogenic acid. While gallic acid value of 3rd and 4th week apple vinegar were detected 11.91 and 23.69 mg L-1, respectively; chlorogenic acid value of 4th and 5th week apple vinegar were found 46.36 and 49.71 mg L-1. Antioxidant activity and phenolic substances values were not significant reduction during the acetic acid fermentation. In this study, the formation process of the functional and sensory properties of apple cider vinegar due to the change in the weekly antioxidant and bioactive component content of apple cider vinegar was emphasized.