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18.1 Fruits 833

Table 18.23. Flavanones and flavones in citrus fruits a

Polyphenol glucoside b Orange, sweet c Bitter orange Grapefruit Lemon

Fruit Peel Fruit Peel Fruit Peel Fruit Peel

Flavanones

Eriocitrin (Eri-7-rut) 159 59 49 38 183 92 1020 1320

Neoeriocitrin (Eri-7-neo) 27 n.d. 2100 2200 n.d. n.d. n.d. n.d.

Narirutin (Nar-7-rut) 1660 665 170 220 1700 1900 114 225

Naringin (Nar-7-neo) n.d. d n.d. 9790 14,700 13,600 21,000 n.d. n.d.

Hesperidin (Hes-7-rut) 9620 14,100 n.d. n.d. n.d. n.d. 3560 711

Neohesperidin (Hes-7-neo) n.d. n.d. 6840 10,900 210 203 n.d. n.d.

Neoponcirin (Isa-7-rut) 571 421 16 27 53 84 n.d. n.d.

Poncirin (Isa-7-neo) n.d. n.d. 2820 5670 3040 462 n.d. n.d.

Flavones

Rutin (Que-3-rut) 108 n.d. 290 473 51 51 n.d. n.d.

Isorhoifolin (Api-7-rut) 3 11 20 37 n.d. n.d. 158 355

Rhoifolin (Api-7-neo) 15 58 566 1080 95 184 13 29

Diosmin (Dio-7-rut) 14 55 16 38 n.d. n.d. 208 432

Neodiosmin (Dio-7-neo) 77 30 173 438 185 110 n.d. n.d.

a Values in mg/kg fresh weight; n.d., not detected.

b Api: apigenin, Dio: diosmetin, Eri: eriodictyol, Hes: hesperitin, Isa: isosakuranetin, Nar: naringenin, Que: quercetin,

rut: rutinose (O-α-L-Rha p -(1 → 6)-D-Glc p ), neo: neophesperidose (O-α-L-Rha p (1 → 2)-D-Glc p )

c C. sinensis cv. Valencia

d C. sinensis var Brasiliensis cv. Morita contained 14 mg/kg naringin

Table 18.24. Taste of flavanone glycosides a

Compound R R 1 R 2 Taste

quality intensity b

Naringeninrutinoside

rut c H OH neutral –

Naringin neo d H OH bitter 20

Isosacuranetin-rutinoside

rut H OCH 3 neutral –

Poncirin neo H OCH 3 bitter 20

Hesperidin rut OH OCH 3 neutral –

Neohesperidin neo OH OCH 3 bitter 2

Eriocitrin rut OH OH neutral –

Neoeriocitrin neo OH OH bitter 2

a Data for R, R 1 and R 2 refer to Formula 18.28.

b Relative bitterness refers to quinine hydrochloride =

100.

c Rutinosyl.

d Neohesperidosyl.

kali fragmentation to a methylketone (IV), condensation

with isovanillin (V) to the corresponding

chalcone (VI), then hydrogenation:

(18.30)

A sweet compound can be obtained from the

neutral-tasting hesperidin of oranges by first

converting hesperidin to another neutraltasting

compound, hesperidin dihydrochalcone. The

latter can then be hydrolyzed, by acidic or enzymatic

catalysis, to remove the rhamnose residue,

yielding hesperidin dihydrochalcone glucoside,

which is sweet. The use of dihydrochalcones as

sweeteners is discussed in Section 8.8.11.

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