A survey of volatile components of some allium species in terms of s‐alk(en)yl‐l‐cysteine sulphoxides present as flavour precursors

Abstract

The volatile flavour components of 27 Allium species and cultivars, mostly edible but including some decorative species for comparison, have been investigated by a series of gas and thin-layer chromatographic and U.V. spectrophotometric methods. By means of simulation experiments with synthetic precursors and intermediates, the data have been interpreted in terms of the amino acid precursors present in the intact tissues and the species classified as containing (a) S-1-propenyl-, (b) S-2-propenyl-and (c) S-methyl-L-cysteine sulphoxides as their principal flavour precursors. Characteristic examples of the three types are A . cepa L. (onion), A . sativum L. (garlic) and A . aflatunense B. Fedtschenko,respectively. An object of the work has been to demonstrate broad chemical similarities between species as well as their differences, which are emphasised in keys for classification on the basis of morphological characters. In addition to onion, leek, shallot, garlic and chives, species such as A. chinense, A . Jistulosum and A . tuberosum have widespread use as food, particularly in the Far East. The literature on this aspect has been briefly summarised.

Increased Sulfur Precursors and Volatiles Production by the Leek Allium porrum in Response to Specialist Insect Attack

“…The level of PCSO, the main sulfur precursor in leek (Freeman and Whenham, 1975), was measured on a 10-cm segment of the stalk using the Waters Pico-Tag technique (Bidlingmeyer et al, 1984). The sample was weighed and ground in methanol for 40 sec at atmospheric pressure.…”

NUMERICAL TAXONOMIC STUDIES ON SPECIES IN ALLIUM SUBGENUS RHIZIRIDEUM

“…treated Chromosorb W. 80-100 mesh. This procedure is similar to that used by Freeman and Whenham (1975) and the procedure and results are described in detail by ElGadi (1976). Major compounds were provisionally identified by gas chromatography-mass spectrometry.…”

“…Volatile sulphides produced after tissue damage have been investigated, since it has been shown (Saghir, Mann and Yamaguchi, 1965;Saghir, Mann, Ownbey and Berg, 1966;Bernhard, 1970;Freeman and Whenham, 1975) that there is substantial variation between taxa of Allium in the composition of the sulphides produced and that these are readily separable by gas-liquid ehromatography.…”

Flavor Chemistry

“…S-Alk( en)yl-L-cysteine sulfoxides serve as precursors of flavor in the genus. An investigation of 27 Allium species found that they could be placed into three groups based on the predominance of certain amino acid precursors (Freeman and Whenham 1975). The predominant precursors were S-1-propyl (onion), S-2-propenyl (garlic), and S-methyl (A. aflaturense B. Fedtschenko) cysteine sulfoxides.…”