Total Phenolic Content, Antioxidant Activity, and Cross-Cultural Consumer Rejection Threshold in White and Red Wines Functionally Enhanced with Catechin-Rich Extracts

White and red wines spiked with catechin-rich green tea extract and grape seed extract were assessed for phenoliccontent, antioxidant activity, and cross-cultural consumer rejection thresholds in relation to wine as a functional food. Healthfunctionality is an important factor in functional foods, and spiking pure compounds or plant extracts is an effective method toincrease or control functionality. The total phenolic content and antioxidant activity were measured in wines spiked to differentextract concentrations, namely, control and 50, 100, 200, 400, and 800 mg/L, to confirm the dose'response curves in both whiteand red wines. Consumer rejection thresholds (CRTs) were established for spiked wines in a Korean and in an Australian population. Our results showed that the green tea extract and grape seed extract increased the antioxidant activity dosedependently, and the CRTs varied considerably between the Korean and the Australian groups, with Koreans preferring winesspiked with green tea extract and Australians showing a preference for wines spiked with grape seed extract. These results have implications for producing wine products that are enhanced in phenolic compounds and targeted to different cultural groups.