| In order to elucidate the influence of flavor compounds in cucumberfruit qulity and their genetic parameters ten varieties of cucumber were studed, which include North China kind Jiaozhoudi, zhangdiandi, M13, and Yidu, South China kind Jinhan, Hanchangbang, Changyesan and European kind SW, HL-18. The major results summarized below:1 SPME extraction methods were selected to detected cucumber flavor compounds by comparing SHS and distillation methods for preparing samples. Supelwax-10 capillary column, PDMS-Carboxen fiber, proper extract condition and GC parameters were selected according to GC/MS experiments. The analysis of major cucumber flavor compounds were done by GC with same condition of GC/MS, compounds were identified by outer standards and mass spectrometry, and quantification was performed by inner standard, octanal. No special or different compounds were found among three kind of cucumber on major flavor profiles. 10 kinds of new volatile compounds including trans-caryophyllene, alpha-humulene, and acetic acid 2-ethylhexyl ester were found in fresh cucumber fruits. 2. Eight compounds including 2E,6Z-nonadienal and 2Z-nonenal etc. were found to change differently by analyzing contents of major flavor compounds of storage fruits, deformation fruits, different fruits development stage and fruits set on different growing stage, different seasons' fruits. Contents of aldehydes and propionaldehyde reduced on storage and old cucumbers. Trans-caryophyllene disappeared after 3 day of storage. Characteristic flavor compounds 2E,6Z-nonadienal do not reduce. Compared with common fruit, deformation fruits have relative small amount of 2E,6Z-nonadienal and trans-2-nonenal, and relative large amount of hexanal. Contents of aldehydes and propionaldehyde decreasedd while 2E,6Z-nonadienal l increase with the increasing days of fruit development. The highest content of 2E,6Z-nonadienal appeared on the stage of 12 days after flower when fruits become old and unfit for eat. The ratio of 2E,6Z-nonadienal to 2E-nonenal was high when plant growed strongly in young and middle stage then old one. The ratio is also affected by density of fruit setting. Fruits growing in fall had the highest values of this ratio compared with those growing in other seasons.3 Correlation analysis among sensory analysis results ,volatile compounds contents,and tastecompounds showed that 2E,6Z-nonadienal had significant positive relation to some sensory items include aroma, sweetness, comprehensive taste and total scores; trans-caryophyllene have significant relation to sensory scores of aroma , sweetness and comprehensive taste ; while 2E-nonenal were no relation to sensory scores. Hexanal has significant negative relation to many sensory items, so this compound has negative relation on cucumber flavor. 2E-hexenal has significant relation to astringent. Soluble sugar contents have significant positive relation to sweetness and comprehensive taste scores, organic acids and dry weight have no significant relations to sensory items.4 Anatomy structures, contents of fiber, and pectin were detected on four cucumber varieties with high differences on texture demonstrate. The result showed that fruit with thick skin cells, and high density of under skin cells do not crisp; fruit with big diameter vessles, irregular shape cells do not benefit for crisp; high contents of fiber and low contents of pectin are not good for crisp, characters of pectin also have impact on crisp. 5 Genetic parameters analysis on 7 cucumber parents with Griffing 4 model were made on three characters: soluble sugar (SS) content, 2E,6Z-nonadienal content and ratio of 2E,6Z-nonadienal to trans-2-nonenal. These three characters have relative low narrow heredity. The former two characters have high broad heredity. Broad heredity on ratio of 2E,6Z-nonadienal to 2E- nonenal is 64%, its narrow heredity is 40%. Non-additive action of gene have minor impact on it, environment factors have high effect on it, so try to decrease impact of environment is essensial on... |
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