A wide range of phytochemicals have long been used for dietary or neutraceutical purposes (Rao, 2012; Wang and Weller, 2006). Several vitamin homologs or precur­sors, such as b-carotene (for vitamin A), tocopherol (for vitamin E), and ascorbic acid (vitamin C), are widely pro­duced from plants. Numerous nutraceutical phytochem­icals, such as anthocyanin and flavonoids, are known for antioxidant or other bioactivities. Commonly used food or feed additives include lutein, canthaxanthin and b-carotene as dietary or coloring agent, astaxanthin for aquaculture such as salmon farming, essential oils, menthol, camphor, caffeine, tannin, capsaicin, wood fla­vor or liquid smoke (water-diluted bio-oil; Venderbosch
and Prins, 2010; Di Blasi et al., 2010) for flavor or aroma, anthocyanins as antimicrobial agents (Chattopadhyay et al., 2008), papain and bromelain for meat processing, lecithin for emulsification, and dietary fibers. Figure 20.3 shows representative dietary phytochemicals.