Color, phenolic composition, and antioxidant properties of hardaliye (fermented grape beverage) under different storage conditions

Authors: BUKET AŞKIN, AZİZE ATİK

Abstract: This study was conducted to determine the effects of storage temperature and time on color and antioxidant properties of hardaliye. Hardaliye was obtained from papazkarası blue-black grapes as a potential source of anthocyanin pigment and high antioxidant activity. Grape variety plays a significant role in color, flavor, and chemical properties. However, the effects of storage conditions on products and especially on phenolic composition and antioxidant properties are not known because there is not any research about storage effects at different temperatures. For this purpose, hardaliye was produced by the conventional method. After having been exposed to lactic acid fermentation, it was bottled and then stored at 4 °C and 20 °C for 60 days. The analyses were carried out on prepared beverage at 15, 30, 45, and 60 days of storage. The results of color parameters obtained showed the highest proportion of red color in the samples at the beginning (dA % = 94.87%). As expected, the brown color increased with storage time and the highest value was determined at 60 days depending on the storage temperature. Storage at 4 °C and 20 °C resulted in 60% and 78% losses in anthocyanin content, respectively. The losses of anthocyanin during storage at the higher temperature were accompanied by increased polymeric color values and other color parameters, which indicates that anthocyanins were also extensively polymerized. Phenol compositions were also analyzed using an LC-MS-MS system. It was revealed that malvidin-3-O-glucoside was the predominant anthocyanin and also that hardaliye has high amounts of resveratrol. A high content of total phenolic (1743 ± 8.67 mg of gallic acid equivalents L^-1) and antioxidant activity value (8.53 mM Trolox mL^-1) is present in the fresh beverage. There was a significant decrease in total phenols during storage, irrespective of temperature.

Keywords: Anthocyanin, color, grape juice, hardaliye

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