Effects Analysis Of Postharvest BTH Treatment On Terpenoids Aroma Compounds And Metabolism Of "Yujinxiang" Muskmelon

"Yujinxiang " muskmelon(Cucumis melo L.cv.Yujinxiang)is susceptible to decay and deteriorated in quality during postharvest storage.BTH treatment can induce its disease resistance,reduce the postharvest rot rate,and extend fruits’ shelf life.Composition of aroma is an important indicator for the quality evaluation of melon fruits,it will change due to the treatment of the inducer."Yujinxiang" muskmelons were treated by BTH after harvest,the terpenes aroma components were monitored during storage at room temperature,the changes were observed on the content of metabolic precursors soluble sugar,pyruvic acid,glyceraldehyde-3-phosphate and IPP and the enzyme activity of related metabolic enzymes HK,PK,HMGR and DXR,then the correlation between factors were analysied,and the influenced mechanism of postharvest BTH inducted treatment was discussed on the relase of terpenoids aroma from melon fruits.The results indicated:1.A total of 12 terpenoids aroma compounds were detected in the samples,including 9 monoterpenes: geraniol,α-terpineol,cis-α,α-5-trimethyl-5-vinyltetrahydrofuran 2-Methanol,L-carvone,p-menthol(7),8(10)-dien-9-ol,trans-(+)-isolimonene,L-menthol,anisic aldehyde,Euphyllol;1 sesquiterpenoid: farnesol;2 C13-isoprenyl compounds: geranyl acetone and β-ionone.Postharvest BTH treatment could delay the release peak time of terpenoids aroma compounds and reduce the release content of monoterpenes and sesquiterpenoids,but it had no obvious inhibitory effect on C13-isoprenyl compounds.2.Postharvest BTH treatment can inhibit the degradation of metabolic precursors soluble sugars,pyruvic acid,glyceraldehyde-3-phosphate and IPP.3.Postharvest BTH treatment inhibited the terpenoids aroma metabolic enzyme activities of HK,PK,HMGR and DXR,and delayed the peak activity of HK and DXR.The inhibition rate of enzyme activity in pulp was higher than in peel.4.Postharvest BTH treatment had no effect on the correlation of L-menthol,eucalipol and DXR enzyme activity,and PK enzyme activity with farnesol release;but it would enhance the correlation of α-terpineol,cis-α,α-5-tris-5-trimethyl-5-vinyltetrahydrofuran-2-methanol,L-carvone,p-menthol-(7),8(10)-diene-9-ol with DXR enzyme activity(P<0.05)and anisic aldehyde with DXR enzyme activity(P<0.01).The correlation between trans-(+)-isolimonene and DXR enzyme activity and the correlation between HK and HMGR enzyme activity and farnesol were weakened by BTH treatment.5.BTH treatment weaked the correlation between farnesol and soluble sugars and the correlation between total monoterpene and IPP,and increased the positive correlation between total C13-isoprenyl compounds and IPP.But there was no effects of the correlation of monoterpenes and total amout C13-isopren compounds with soluble sugars,glyceraldehyde-3-phosphate and pyruvic acid,and the correlation of farnesol with pyruvic acid and IPP.In summary,postharvest BTH treatment could effectively reduce the susceptibility of the samples,inhibit the content decrease of metabolic precursors and the metabolic enzyme activities of the samples,and then changed the correlation between the metabolic factors of terpenoids aroma compounds,and affected the release of aroma components.