Food Chemistry

834 18 Fruits and Fruit Products

Table 18.25.Taste of dihydrochalcones

Dihydrochalcone Tastes
from

quality intensitya Relative

(μmole/l) intensityb

Naringin sweet 200 1

Neohesperidin sweet 10 20
Neoeriocitrin slightly

sweet – –
Poncirin slightly
bitter – –

Saccharin

(Sodium salt) sweet 200 1

aConcentration of iso-sweet solutions.
bRelated to saccharin.

The dihydrochalcone glycoside phloridzin (For-
mula 18.31) occurs in apples.

(18.31)

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:lute-
olin; 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-glyco-
sides (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).

Table 18.26.Occurrence of flavonols in fruit

Fruit Flavonols

Apple Que-3-gal, Que-3-

glc, Que-3-rha,

Que-3-rha-glc,

Que-3-ara,

Que-3-xyl

Pear Que-3-glc

Peach Que-3-glc

Apricot Que-3-glc,

Kaem-gly

Plum/prune Que-3-glc, Que-3-

rha, Que-3-ara

Sour cherry

Sweet cherry Que-3-glc

Blackberry Que-3-glc

Strawberry

Currant, black Que-3-glc, Kaem-

3-glc, Myr-3-glc,

further Que-glc,

Kaem-glc

Raspberry

Grapes 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.

(18.32)

They are faintly yellow compounds.