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The flavor of fruits and vegetables are extremely important to their acceptance in the diet.
Sweetness may result from the presence of glucose, galactose, fructose, ribose, arabinose and xylose.
All fruits and vegetables naturally contain a small amount of salt, which is detected in the overall taste impressions contributing to flavor.
The natural flavor of vegetables are due to mixtures of aldehydes, alcohol, ketones, organic acids and sulphur compounds. Some fruits and vegetables have an astringent taste attributed to phenolic compounds or tannins.
Two types of vegetable have strong flavours resulting from the presence of various sulphur containing compounds. Allyl sulphide found in onions, garlic and leeks. Brussle sprouts, broccoli, cabbage, turnips, cauliflower, kale and mustard are members of the family cruciferae, which also contain prominent volatile sulphur compounds.
Table: Flavour components of sulphur containing vegetables
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Vegetables
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Precursor
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Reaction with treatment
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Final volatile compound
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Garlic
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Alliin s-2-Propenyl (allyl) cysteine sulphoxide
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Cutting/ Crushing results in allicin formation
This undergoes nonenzymatic decomposition to disulphide and thiosulphinate
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Disulphide further decomposes to a complex mixture of mono-sulphide and tri-sulphide – characteristic flavor
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Onion
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S-1-Propenyle cysteine sulphoxide
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Cutting/ Crushing results in formation of sulphenic acids which is unstable and undergoes rearrangement
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Thiopropanal-S-oxide- lachrymatory factor
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Brassica family- Cabbage, cauliflower
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S-methyl-cysteine sulphoxide and thioglucosides
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Cooking
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Dimethyl sulphides and isothiocyanates- give off-flavour
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An amino acid s-methyl 1- cysteine sulphoxide is also present in raw cabbage and appear to be a precursor of cooked cabbage flavor.
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Participants