|Author: ||W.M. Randle|
|Keywords: ||S-alk(en)yl cysteine sulfoxides, breeding, sulphur, selection|
Onion flavours are dominated by primary and secondary products from the enzymatic decomposition of unique sulphur compounds collectively known as S-alk(en)yl cysteine sulfoxides (ACSO). The synthesis of the ACSOs occurs when sulphur is absorbed by the plant and metabolized through the ACSO biosynthetic pathway.
The metabolism of sulphur through the biosynthetic pathway leading to the synthesis of the ACSOs, and the decomposition of the ACSOs are highly variable among and within onion cultivars.
Understanding this variation may be used to develop strategies for flavour manipulation with the intent to provide specific flavour intensities or flavour profiles.
Breeding opportunities which may affect final flavour include: differential sulfate absorption influenced by root morphology or S-permease concentration; total bulb sulphur accumulation; the sulfate to organic sulphur ratio influenced by cysteine synthase or other enzymes specific to the ACSO biosynthetic pathway; differential accumulation of individual ACSOs; or alliinase manipulation.
Onion flavour is strongly influenced by the growing environment, and by the time of product consumption.
Therefore, the evaluation of flavour should be done under uniform growing conditions or at the time when the product is normally consumed.
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