Synthetic and natural antioxidant additives in food stabilization: current applications and future research - Oxidation in Foods and Beverages and Antioxidant Applications - page 290

Fig. 12.10 Less polar compounds isolated from oregano.
While the rosmarinic acid content of rosemary and oregano is similar, carnosic
acid and carnosol levels are present at a much lower levels in oregano than in
rosemary (HernÂndez-HernÂndez et al., 2009). Oregano seems to be rich in other,
less polar, antioxidants identified as apigenin (flavone), eriodictyol (flavanone),
dihydroquercetin (dihydroflavonol) and dihydrokaemferol (dihydroflavonol).
These showed high efficacy in protecting lard and vegetable oil against lipid
oxidation (Vekiari et al., 1993) (Fig. 12.10). Nakatani (1994) reported the
presence of a water soluble glycoside, rosmarinic acid and a rosmarinic acid
congener, in addition to several polyhydroxy benzoic and cinnamic acids in
oregano (Fig. 12.11).
The essential oil of the oregano is also very active due to the presence of
carvacrol and thymol (Botsoglou et al., 2002). As with any of the essential oils,
the high flavor levels of these ingredients greatly limits their utility.
Some of the foods that have been preserved with oregano include vegetable
oils (Pokorn  et al., 2001), lard (Banias et al., 1992), oil-in-water fish oil
emulsions (Jimenez-Alvarez et al., 2008). Oregano is effective in meat.
HernÂndez-HernÂndez et al. (2009) showed that oregano slowed color loss and
lipid oxidation in raw pork batters. Supplementing oregano oil in the diet was
shown to improve the quality of the meat in chicken (Botsoglou et al., 2002),
lamb (Simitzis et al., 2008) and turkey (Govaris et al., 2004).
Tea (Thea sinensis L.)
It is commonly recognized that the main active phenolics in fresh tea are
polyphenols known as catechins. Catechins are enzymatically oxidized during
fermentation to yield theaflavins and thearubigens (dark compounds in tea). The
structures of major catechins and theaflavins are elucidated as: epicatechin (EC),
epicatechin gallate (ECG), epigallocatechin (EGC), epigallocatechin gallate