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citrullus_lanatus_thunb._matsum._nakai

Citrullus lanatus (Thunb.) Matsum. & Nakai - syn. Citrullus vulgaris Schrad.; Cucurbita citrullus L.; Colocynthis citrullus (L.) Kuntze; Momordica lanata Thunb. - Cucurbitaceae
(dessert) watermelon, Wassermelone

Annual plant, derived from varieties growing in West Africa, commonly cultivated; stem and branches robust, sulcate-angular, villous; tendrils puberulent, 2-fidleaves white-green, triangulate-ovate, both surfaces hispid, 3-partite; flowers solitary; male flowers: calyx tube densely villous, corolla pale yellow, stamens nearly free; female flowers: calyx and corolla as in male flowers, ovary 5-8 mm, densely villous, stigmas 3; fruit globose or oblong, outside green-yellowish, fruit flesh usuallay red; seeds numerous, ovate.
„The fruit are important [refreshing and thirst quenching] 'water fruit' in summer; the seeds contain edible oil; the fruit coat is used medicinally.“ http://www.efloras.org/florataxon.aspx?flora_id=2&taxon_id=200022609

„The fruit has a smooth hard rind, usually green with dark green stripes or yellow spots, and a juicy, sweet interior flesh, usually deep red to pink, but sometimes orange, yellow, or white, with many seeds… The seeds have a nutty flavor and can be dried and roasted, or ground into flour… Another objective of plant breeders has been the elimination of the seeds which occur scattered throughout the flesh. This has been achieved through the use of triploid varieties, but these are sterile, and the cost of producing the seed, through crossing a tetraploid parent with a normal diploid parent, is high.“ http://en.wikipedia.org/wiki/Watermelon

„…both (Z)-3-nonenal and (Z,Z)-3,6-nonadienal had green and somewhat watermelon-like odors. (Z)-3-Nonen-1-ol found in Fractions 5 and 6 in large quantities had a pleasant and somewhat fresh melon-like odor. (Z,Z)-3,6-Nonadien-1-ol was also found in Fractions 5 and 6, and the odor of this compound was sweet and watermelon-like. This compound was thought to be the most powerful contributor to the characteristic aroma of watermelon judging from its odor characteristic… (Z,Z)-3,6-Nonadien-1-ol, known to possess an odor reminiscent of that of watermelon or watermelon rind, has been found in watermelon, muskmelon, and cucumber.“
[Volatile flavor components of watermelon (Citrullus vulgaris)., Yajima, I., Sakakibara, H., Ide, J., Yanai, T., Kazuo, H., Agricultural and Biological Chemistry, 49(11), 1985, 3145-3150] http://www.tandfonline.com/doi/pdf/10.1080/00021369.1985.10867246

(Z)-3-nonen-1-ol
(Z)-3-Nonen-1-ol
(fresh melon)
(Z,Z)-3,6-nonadien-1-ol
(Z,Z)-3,6-nonadien-1-ol
(sweet peely watermelon)
(Z,Z)-3,6-nonadienal
(Z,Z)-3,6-nonadienal
(fresh-cut watermelon)

„Fully ripe watermelon was squeezed through miracloth to produce rapid juice extracts for immediate headspace SPME GC-MS. Aldehydes, alcohols, ketones, and one furan (2-pentyl furan, a lipid oxidation product) were recovered. On the basis of total ion count peak area, the most abundant compounds in five varieties were 3-nonen-1-ol/(E,Z)-2,6-nonadienal (16.5-28.2%), (E)-2-nonenal (10.6-22.5%), and (Z)-6-nonenal (2.0-11.3%). Hexanal was most abundant (37.7%) in one variety (Petite Perfection)… The most abundant ketone was 6-methyl-5-hepten-2-one (2.7-7.7%).“
[Characterization and semiquantitative analysis of volatiles in seedless watermelon varieties using solid-phase microextraction. Beaulieu JC1, Lea JM., J Agric Food Chem. 2006 Oct 4;54(20):7789-93]

„The key to identifying the key components responsible for fresh-cut watermelon aroma was the application of a suitable volatile isolation strategy based on static headspace analysis (SHA). In this study, SHA was used to collect the headspace volatiles one minute after initial cutting of the fruit. This enabled a chemical “snap shot” of fresh-cut aroma to be taken. The most potent odorants in the headspace were determined by gas chromatography-olfactometry of decreasing headspace volumes (GCO-H) with confirmation achieved by application of a complimentary method based on GCO and aroma extract dilution analysis (AEDA) of fresh-cut watermelon aroma extracts prepared by solvent-assisted flavor evaporation (SAFE). Eight unsaturated nine-carbon aliphatic aldehydes and one six carbon unsaturated aldehyde were detected by GCO-H. These included cis-3-hexenal, cis,cis-3,6-nonadienal, cis-3-nonenal, cis-6-nonenal, trans-2-nonenal, cis-2-nonenal, trans,cis-2,6-nonadienal, trans,trans-2,4-nonadienal, and trans,trans,cis-2,4,6-nonatrienal. This finding is contrary to previous beliefs that alcohols are the main contributors to fresh-cut watermelon aroma. Most importantly, it was found that cis,cis-3,6-nonadienal was not only a potent odorant, but this compound alone possessed an aroma reminiscent of fresh-cut watermelon. Use of sensory evaluation, including ranking test, revealed that the aroma attributes of purified synthetic cis,cis-3,6-nonadienal closely matched those of fresh-cut watermelon. This “watermelon aldehyde” can be considered a potent odorants since its estimated odor detection threshold (in water) is very low (0.2 ppb). Unfortunately, cis,cis-3,6-nonadienal is a labile compound and is prone to both trans isomerization and oxidation of its aldehyde end group.“
[Genthner, Elizabeth R. Identification of key odorants in fresh-cut watermelon aroma and structure-odor relationships of cis,cis-3,6-nonadienal and ester analogs with cis, cis-3,6-nonadiene, cis-3-nonene and cis-6-nonene backbone structures. Diss. University of Illinois at Urbana-Champaign, 2010]
https://www.ideals.illinois.edu/bitstream/handle/2142/16898/2_Genthner_Elizabeth.pdf

„The dominant components detected by solid phase microextraction were six- (C6) and nine-carbon (C9) alcohols and aldehydes, similar to those found in watermelon extracts and in other cucurbits… Nine-carbon compounds have been attributed aromas typical of watermelon, melon, and other cucurbits. For instance, (Z)-3-nonenol imparts a fresh melon scent, (Z,Z)-3,6-nonadienol imparts a sweet peeled watermelon scent, (E,Z)-2,6-nonadienal and a cucumber scent and (E)-2-nonenal, a pervasive oily odor. (Z,Z)-3,6-nonadienol alcohol was found to contribute more to the watermelon scent (YAJIMA et al., 1995). These reports agree with the results of this study since with the help of chromatography/olfactometry it was concluded that characteristic watermelon scent is mainly imparted by nine-carbon aldehydes and alcohols…
Another compound observed was 6-methyl-5-hepten-2-one, imparting a herbal, green, oily and pungent aroma. This compound has been recovered from several types of vegetables including apple, tomato, and watermelon. According to the literature, it is considered an oxidative by-product or a product obtained from the degradation of lycopene, α-farnesene, citral, or conjugated trienols. Hence, the detection of 6-methyl-5-hepten-2-one ketone is not unexpected due to the high concentration of lycopene found in watermelon.“
[Volatile profile and physical, chemical, and biochemical changes in fresh cut watermelon during storage. Xisto, Andréa Luiza Ramos Pereira, Boas, Eduardo Valério de Barros Vilas, Nunes, Elisângela Elena, Federal, Brígida Monteiro Vilas Boas, & Guerreiro, Mário César. Food Science and Technology (Campinas), 32(1), 2012, 173-178]


Citrullus lanatum fruits at a market wikimedia commons , Author: Judgefloro, CC-BY 4.0

citrullus_lanatus_thunb._matsum._nakai.txt · Zuletzt geändert: 2016/07/20 10:44 von andreas