Table 6.

Nutraceuticals retained after food bioprocessing: metabolism by gut microflora

Protectant (additive)	Source in feedstock
Quercetin (flavonoid)	Onions and tea
Lycopene (carotenoid) removes singlet state molecular oxygen (·ΔgO2)	Red tomato derived (Crozier et al. 1997)
Phytoestrogen (isoflavones) (Bowey et al. 1998; Wiseman et al. 2002)	Soya protein

Phytoestrogen isoflavones include the soya protein‐derived glucones daidzin and genistin. These are degraded to the aglycone forms daidzein and genistein by gut microflora: and these initial products can be degraded further by other bacteria in the gut for example to equol derivatives and equol conjugates with glucuronic acid (excreted through the kidney). Fermented soya foods, such as miso or tempeh, contain mostly the unconjugated isoflavone aglycones (Wiseman et al. 2002).