Identification Of Characteristic Flavour Compounds In Snap Bean(Phaseolus Vulgaris L. Var. Chinensis Hort.) And Analysis On Influence Factors

Snap bean(Phaseolus vulgaris L. var. chinensis Hort.)are a kinds of importan fruit vegetables in our country for its special flavor quality and excellent nutritional quality. Green pods are edible organs of snap bean,which have planted all over the country. With the expanding of snap bean market both and improving of vegetables quality requirements, comprehensively investigated of snap bean flavor quality was urgently needed. But the study on snap bean quality concentrated in nutritional qualityat present, flavor quality has harly any been reported before. The chemical components that contributed toflavor quality of snap bean and the influence factors of flavor compounds content remains unclear.In order to provide theoretical information for snap bean cultivation, breeding and processing, snap bean cultivars were chosen as the experiment material. Headspace solid phase microextraction(HS-SPME) with gas chromatography-mass spectrometry(GC-MS) techniques and High-performance liquid chromatography(HPLC) were applied to study the volatile compounds and taste-active compounds of snap bean pods. The characteristic aroma compounds and taste amino acid were identified by instrumental analysis. Effect of different influencing factors on the flavour constituents of snap bean was studied.The main results as follows:1.Optimization the analysis method of headspace solid phase microextraction extraction in snap bean pods volatile components: 65 um PDMS/DVB extraction fiber was suitable for snap bean pod flavour extraction, the flavour volatiles of crude pods was extracted at 60℃ for 60 min and cooked pods at 80℃ for 50 min, desorption time was 3min.2.The characteristic aroma compounds was 1-Octen-3-ol, which contributed to aroma of snap bean cooked pods with 2,6,6-trimethyl-1-Cyclohexene-1-carboxaldehyde, 4-(2,6,6-trimethyl-1-cyclohexen-1-yl)-3- Buten-2-one, Hexadecanoic acid methyl ester, 3-Octanone,Decanal,(E)-2-Hexen-1-ol,Octanal. The main volatile compounds of snap bean were aldehydes, alcohols, ketones, acids, esters ethers. 30~46 volatile compounds were identified in cooked pods, content of 1-Octen-3-ol was 197.04 ug/kg~400.41ug/kg,and relative content was 23.25%~39.06%. Contents and numbers of volatile components Baiyunfeng were higher than other cultivars(Dwarf Bayuelu, Thailand Jiadou and Provider).Aroma quality of sprawl cultivars is superior to dwarf cultivars, and flat strip pod varieties is better than the stick-like pod varieties.3.Free aspartic acid and glutamic acid was the characteristictaste amino acid of snap bean. The content of free aspartic acid and free glutamic acid was 0.319 mg/g~0.478mg/g and 0.052 mg/g~0.123 mg/g, respectively. Snap bean had all amino acids types with the total amino acids contentof 5.90 mg/g ~16.72mg/g.The ratio of essential amino acids to total amino acids was 37.76%~42.26%. Aspartic acid and glutamic acid were the most abundant two types, accounting for 15.24%~19.95% and 13.52%~16.90%,respectively. Isoleucine and methionine were the limiting amino acids.Contents of characteristictaste amino acid and total amino acids of Youdoujiao(Baiyunfeng) were higher than other cultivars(Drawf Bayuelu,Thailand Jiadou and Provider).4.Flavor quality of snap bean was influenced by varieties,the growth period of pods, storage methods, cultivation practices.(1)The contents of characteristic flavor compounds varied greatly among different snap bean cultivars, Flat strip type cultivars flavour quality was superior to baton type cultivars, Sprawl cultivars was superior to dwarf cultivars,Northeast Youdoujiao was an excellent cultivar group of snap bean.(2)The characteristic flavor compounds content of snap bean pods was the highest value at commercial maturity, optimum harvest time was 18±3 age of pods.(3) Blanching and fast frozen process could cause water and characteristic flavor compounds loss. Flavor quality was relatively stable before 90 days storage, content of flavor compounds decreased continuously with the increasing of frozen storage time after 90 days.(4) The snap bean flavour quality in open field was better than greenhouse.The content of flavor compounds decreased with the decrease of light intensity,impact on dwarf cultivars greater than sprawl cultivar. Flavour quality of black soil cultivation was superior to chernozem cultivation. Therefore, to improve the flavor quality of snap bean, fine varieties should be cultivated in black soil and chernozem region, northeast Youdoujiao could be chosen under the optimum cultivation conditions, and the cultivation environment should have adequate lighting. Fast frozen process could be used for storing snap bean pods during full harvesting,but storage time should be shortened as much as possible.