6.7.2. Flavonoids

At least 25 di fferent flavonoids have been identified in almonds. Anthocyanidins, flavan-3-ols, flavonols, flavanones and a biflavone have been identified in almond, almond skins, or almond blanch water [107].

Most flavonoids of almond kernel appear exclusively in the skin, while non-flavonoids phenols appear in the seed. Flavonoids of almond skin act as phytoalexins, protecting dry seeds against bacteria, fungi and other environmental stressors [132]. The flavonoids group can be divided in seven categories that include flavonols, flavones, isoflavones, flavanols, flavanones, anthocyanins and dihydrochalcones.

Flavonols were the most abundant flavonoid class in almond and include isorhamnetin-3-O-glucoside, isorhamnetin-3-O-rutinoside, kaempferol-3-O-glucoside, quercetin-3-O-glucoside, quercetin-3-O-rutinoside, galactosides and rutinosides [107]. They have been identified, but rarely quantified (Table 6).

Flavonoid composition in plants is influenced by genetic factors and environmental conditions, excluding exposure to fungi and bacteria, parasites, climate and UV light [81,112,118].
