Cucumber flavour

The fruit of the cucumber plant Cucumis sativus) is mainly eaten raw or as pickle. Approximately 30 volatile compounds have been detected in the volatile fraction of cucumber, with aliphatic alcohols and carbonyl compounds being most abundant [35]. Fresh cucumber flavour develops as a result of enzymatic degradation of linoleic and linolenic acid rapidly after the tissue is disrupted (Scheme 7.2), by which ( ,Z)-2,6-nonadienal and ( )-2-nonenal mainly are formed [184]. ( ,Z)-2,6-Nonadienal is the main flavour volatile of cucumber fruit, with ( )-2-nonenal as the second most important compound (Table 7.7) [185, 186]. 

The modern distinction between vegetable and fruit has been applied and therefore those plants or plant parts that are usually consumed with the main course of a meal will be regarded as vegetables thus, cucumber, tomato and pumpkin that botanically are classified as fruits are included in this section. The flavour compounds found in vegetables are diverse and include fatty acid derivatives, terpenes, sulfur compounds as well as alkaloids. This diversity is partially responsible for the unique flavours found in different species of vegetables. 

Key flavour compounds Cucumber Cucumis sativus) Pumpkin Cucurbita pepo)... 

In contrast, odour intensity of other components related to off flavours ( herbal , sawdust , greasy , and cucumber ) can be seen to decrease with toasting. The same happened with the intensity of fruity and floral aromas of linalool oxide, p-damascenone, or 2-phenylethanol, and the oak lactones odour descriptors. 

Peroxidase Horse radish, apple, bean, grape, barley, potato, cucumber, pea, peanut, tomato Ripening of foods, several functions in plants, colour formation (off-) flavour formation. 

CIC In both melon types the lipid degradation products (Z)-6-nonenol, (Z,Z)-3,6-nonadienol and the corresponding aldehydes are responsible for the typical green, fatty, cucumber melon aspect. Ethyl propionate imparts an overripe character to muskmelon flavour, supported by the sweet, caramelic aspect of 2-methyl-5-ethyl-4-hydroxy-furan-3(2H)-one and the fmity-sulphurous aroma of S-methyl thioacetate and methyl thiobutyrate. 

Other plant systems effect degradation of the hydroperoxides to short-chain aldehydes which have important flavour properties. For example, when cucumber cells are broken and the enzymes liberated, lipolysis, enz5rmic oxidation and subsequent chain hssion give hexanal (from 18 2),... 

Found in Cucumis sativus (cucumbers), watermelons and prickly pears. Used in perfumes and as a flavouring agent in tobacco substitutes. Liq. Bpn 98-100°. 

One promising approach might be the application of defined starter cultures that are capable of growing rapidly and that are highly competitive in the environmental conditions under which the product is kept Therefore, numerous attempts have made especially to ferment cabbage to sauerkraut, but also to ferment cucumbers and olives by defined starter cultures. Especially in the case of sauerkraut, most of the experiments performed with pure cultures or mixtures of pure cultures led indeed to the desired uniform, sufficient and rapid acidification of the products. But they lacked the typical rounded sauerkraut flavour, which essentially is due to the lack of certain fermentation by-products or the insufficient decomposition of compounds characteristic for the respective raw material (Kandler, 1981). Sauerkraut with perfect sensorial characteristics was obtained with selected strains of L. mesenteroides, which simultaneously improved the uniformity of sauerkraut from different batches. However, even in this case, so far no such benefits could be achieved compared to spontaneous fermentation that would economically justify the cost of the production of starter cultures (Buckenhueskes Hammes, 1990). 

Termination reactions may lead to the formation of both high and low molecular weight products of the peroxidation reactions. Depending on the lipid, some of the low molecular mass compounds may be important flavours (or aromas) of foods (section 5.2.3). For example, short to medium chain aldehydes formed from unsaturated fatty acids may give rise to rancidity and bitter flavours on the one hand or more pleasant attributes such as those associated with fresh green leaves, oranges or cucumbers on... 

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