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

Abstract

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. fistulosum and A. tuberosum have widespread use as food, particularly in the Far East. The literature on this aspect has been briefly summarised.