Agriculture Reference
In-Depth Information
Table 8.1.
Flavour precursors (cysteine sulfoxides) detected in edible alliums and
their relative amounts (based on more detailed information from Lancaster and
Boland, 1990, Table 1).
Flavour precursor
S-methyl
S-propyl
S-(1-propenyl)
S-(2-propenyl)
Species
(MSO)
(PSO)
(1-PECSO)
(2-PECSO)
Onion,
A. cepa
+
+ +
+ + +
0
Shallot,
A. cepa
var.
ascalonicum
+ +
+ +
+
0
Rakkyo,
A. chinense
+ +
+
+ +
0
Japanese bunching onion,
A. fistulosum
+
+ +
+ +
0
Chives,
A. schoenoprasum
+
+
+ +
0
Leek,
A. ampeloprasum
+ +
+ +
+
0
Great-headed garlic,
A. ampeloprasum
+ +
+
0
+ + +
Garlic,
A. sativum
+ +
+
0
+ + +
Chinese chives,
A. tuberosum
+ +
+
+
+ + +
Fig. 8.1.
-glutamyl-trans-(+)-s-(1-propenyl)-cysteine sulfoxide (upper), which forms
approximately 50% of the potential flavour precursors in onion bulbs. As shown, it
is split from the
-glutamyl transpeptidase enzyme to
produce trans-(+)-s-(1-propenyl)-cysteine sulfoxide (abbreviated to
1-PECSO) (lower). This can be converted to flavour volatiles by the alliinase
enzyme reaction of Fig. 8.2 (part of Fig.14.4 of Randle and Lancaster, 2002).
-glutamyl group by the
