338 Handbook of herbs and spices
as well as many other vitamins and minerals. The unique spicy flavour comes mostly
from volatile sulphur and glucosides, etc. Studies into the chemistry of Allium flavour
began in the 18th century. So far, much has been learned about Allium chemistry,
although many questions still remain (Block, 1992). We have learned that the flavour
is the result of a multifaceted interaction among many different compounds, and we
have also begun to understand the factors that affect the quality and intensity of the
flavour of Allium. The flavour substances of various Allium species depend on the
quantitative differences in the S-alk(en)yl cysteine sulphoxides (ACSOs). The S-
alk(en)yl cysteine sulphoxides (ACSOs), when hydrolyzed by the enzyme allinase,
give rise to the flavour and pungency characteristic of the Allium plants (Randle and
Lancaster, 2002). When the tissues of Allium are disrupted, the enzyme allinase
hydrolyzes the flavour precursors. Sulphur compounds are found in the cytoplasm of
Allium cells, physically separated from allinase (Lancaster and Collin, 1981).
In Allium species, four different ACSOs have been identified (Bernhard, 1970;
Freeman and Whenham, 1975; Yoo and Pike, 1998; Randle and Lancaster, 2002). 2-
methyl-2-butenal, 2-methyl-2-pentenal, methyl-propyldisulphide, and dipropyldisuphide
have been found in the green leaves of chives. There is also evidence for the presence
of propencyl-propyldisulphide in chives, while allyl disulphide is definitely absent
(Wahlroos and Virtanen, 1965). The major thiosulfinate from chive are n-propyl
groups, methyl and 1-propenl groups. The data of Table 19.2 are both qualitative and
semi-quantitative (Block et al., 1992).
Of the thiosulfates found in chives, 77 (75)% contain the n-propyl group, 10 (12)%
contain the methyl and 12% contain the 1-Propyl group. Total thiosufates is 0.19 umol/
g wet (fresh), about the middle level of the edible species of Allium. The n-propyl group
in chives is more abundant than methyl, with the methyl/propyl 1:5.8. Chives have an
onion-like flavour. The pungent and stimulating flavour of chives and onions is mainly
due to the propyl group, but it is the quantitative and qualitative differences in the
thiosulfates that give each species its own characteristic flavour. The flavour and
lachrymatory properties of chives are due to the high n-propyl content, while the
flavour of onions is due to the high proportion the 1-propyl it contains.
It has been recognized that factors affecting flavour intensity and quality include
genetic, ecological and cultivation techniques. Chives grown in different years, areas
and different cultivars, with different cultivation techniques, may have distinct flavour
intensities.
Chives also contain flavonoid glycosides, as shown in Table 19.3. The biological
activities of flavonoids are mainly due to their antioxidant function. They are also
known to inhibit several enzymes, including lipoxgenases and cyclo-oxygenase, etc.
The green leaves of chive mainly contain kaempferol glucosides (di- and tri-glycosides),
dominant as glucose and galactose. The 3-beta-D-glucosides of kaempferol, quercetin
and isorthamnetin were isolated (Starke and Herrmann, 1976).
Table 19.1 Approximate chemical composition of chives (6) (7)*
% CND Pro Fat Fib Ash A C B1 B2 Ca P K Na Mg Fe S Volatile
Water o: 1
92.0 26 3.9 2.8 0.6 0.9 0.8 6400 70 0.10 0.12 0.60 82 46 250 6 55 1.2 93 25–26
Source: Adapted from Rubatzky and Yamaguchi, 1997.
*Epmakov, 1961.
Calories Niacin