2009_Book_FoodChemistry

834 18 Fruits and Fruit Products
Table 18.25. Taste of dihydrochalcones
Dihydrochalcone
from
Tastes
quality intensity a Relative
(µmole/l) intensity b
Naringin sweet 200 1
Neohesperidin sweet 10 20
Neoeriocitrin slightly
sweet – –
Poncirin slightly
bitter – –
Saccharin
(Sodium salt) sweet 200 1
a Concentration of iso-sweet solutions.
b Related to saccharin.
The dihydrochalcone glycoside phloridzin (Formula
18.31) occurs in apples.
(18.31)
Table 18.26. Occurrence of flavonols in fruit
Fruit
Apple
Pear
Peach
Apricot
Plum/prune
Sour cherry
Sweet cherry
Blackberry
Strawberry
Currant, black
Raspberry
Grapes
Flavonols
Que-3-gal, Que-3-
glc, Que-3-rha,
Que-3-rha-glc,
Que-3-ara,
Que-3-xyl
Que-3-glc
Que-3-glc
Que-3-glc,
Kaem-gly
Que-3-glc, Que-3-
rha, Que-3-ara
Que-3-glc
Que-3-glc
Que-3-glc, Kaem-
3-glc, Myr-3-glc,
further Que-glc,
Kaem-glc
Que-3-rha, Que-3-
glc, Que-3-rha-glc
Kaem: kaempferol, Myr: myricetin, Que: quercetin.
ara: arabinoside, gal: galactoside, glc: glucoside,
gly: glycoside, rha: rhamnoside, and xyl: xyloside.
18.1.2.5.5 Flavones, Flavonols
Flavones (Formula 18.32: I, R = H; R 1 ,R 2 =H,
R 3 = OH: apigenin; R 1 ,R 2 = OH, R 3 =H:luteolin;
R 1 = OH, R 2 =H,R 3 =OCH 3 : diosmetin;
R 1 =OCH 3 ,R 2 =H,R 3 = OH: chrysoeriol; II:
nobiletin) and flavonols (Formula 18.32: I, R,
R 3 = OH; R 1 ,R 2 = H: kaempferol; R 1 = OH,
R 2 = H: quercetin; R 1 ,R 2 = OH: myricetin; R 1
= OCH 3 , R 2 = H: isorhamnetin) occur in all
common fruits and citrus and tropical fruits as the
3-glycosides and, less frequently, as the 7-glycosides
(Tables 18.23 und 18.26). Quercetin is
a very effective antioxidant (cf. 3.7.3.2.1). Higher
concentrations (mg/kg) have been found in
quince (180), elderberry (170), cranberry (130),
raspberry (70), apple (49), cherry (14) and
red/blackcurrant (13).
They are faintly yellow compounds.
(18.32)