Influence of Grape Seed Phenolic Compounds on Thermal Stability of Frying Oils

摘要

The effects of grape seed phenolic compounds on quality characteristics of a blend of sunflower cottonseed oil during deep-fat frying (at 180℃) of potato chips for 4h/day for 5 days in five systems were determined in this study. The systems used were a blend of sunflower: cotton seed oils (1:1 v/v) without antioxidant (control), with 200 ppm butylated hydroxytoluene (BHT), and 200, 400 and 800 ppm grape seed polyphenols. Analysis was carried out daily after frying to follow up the deterioration the occurred in the oil. Oil samples were analyzed for peroxide value, thiobarbituric acid (TBA) acidity, iodine value, polar content, polymer content, viscosity, ultravilot absorption (E_(1cm)~(1%) at 232 and 268 nm.), color and oxidized fatty acid content. Generally, the blends with 800 ppm grape seed polyphenols gave the least increase in these attributes compared to other three concentrations. Phenolic compounds were found at concentrations 950 ppm (as caffic acid) in grape seed. Polyphenols of grape seed were fractionated by high performance liquid chromatography (HPLC). Five compounds were separated and were identified as gallic acid, catechin, epicatechin, tannic acid and procyanidin.