Furthermore, onion extracts were shown to efficiently inhibit polyphonoloxidase and thereby inhibit enzymatic browning of potato (Lee et al., 2002). In another study, onion extracts suppressed enzymatic browning of pear (Kim et al., 2005). Although onion addition suppresses enzymatic browning, the strong flavor and odor of uncooked onion may prevent its use as a food additive, especially for drinks. An efficient way to reduce the flavor and odor of onion is heat treatment. Furthermore, it has been reported that heating highly increases the functionality of onion, including antioxidant activity, metal chelating capacity, and polyphenol concentration (Kim et al., 2005; Woo et al., 2007).