Effect Of Forchlorfenuron Application On The Bitter Taste And Aroma Of Oriental Melon

Oriental melon(Cucumis melo var.),an important crop of the Cucurbitaceae family,is widely cultivated worldwide.Forchlorfenuron,a plant growth regulator with synthetic cytokinin activity,is widely used to improve fruit set and yield of oriental melon.Our previous study has found that the poor palatability of oriental melon after forchlorfenuron application,especially the bitterness and weaken the aroma of melon fruit.In this study,fragrances oriental melon(459)as the study object,field experiment was conducted to study the relationship between forchlorfenuron treatment and bitterness and aroma of oriental melon.The possible mechanism was analyzed combined with the content of endogenous hormones in oriental melon.The project can provide the quality of oriental melon and providing a basic reference for the ration use of forchlorfenuron,and it can broaden the research area of the effect of pesticide residue on quality,safety,and nutrition.The main research content and results are as follows:(1)Explore the effect of forchlorfenuron application on the bitter taste of oriental melon fruits.The result of human sensory evaluation showed that the high-dose forchlorfenuron can cause the perceived bitter taste in the oriental melon.Cucurbitacin substances were identified as the main bitter compounds in oriental melon,and forchlorfenuron application affected the content and proportion of cucurbitacin substances in the mature oriental melon.Compared with the control group,the application of forchlorfenuron increases the concentration of cucurbitacin B and decreases the arvenin I in total cucurbitacins.The taste activity values(TAVs)factors were calculated by the ratio of the concentrations determined in oriental melon fruit and the corresponding taste thresholds.These TVA data unequivocally demonstrate cucurbitacin B and arvenin I as the key contributor to the bitter taste in oriental melon fruit after high-dose forchlorfenuron application.(2)A SPME-GC×GC-TOF-MS method was developed for the determination of aroma compounds in oriental melon fruit.The extraction method and different column systems were compared and optimized.It was found that the extraction of melon by solid-phase microextraction(SPME)and the addition of sodium chloride to the melon homogenate sample could significantly improve the types and contents of the extracted aroma substances.Meanwhile,the nonpolar column(DB-5MS)a onedimensional chromatography column was more suitable for the analysis of the aroma substances of oriental melon than the polar column(DB-WAX).A total of 175 aroma substances were detected in ripe oriental melons,among which esters accounted for the highest type and relative content and were the main aroma substances in ripe melons.This was followed by other aroma substances such as aldehydes,alcohols,acids,and ketones,and the types and amounts of detected substances were significantly higher compared with previous studies.(3)The effects of different concentrations of forchlorfenuron on melon aroma were explored,and key aroma active substances were screened.In the sensory analysis results,the medium concentration treatment group(15 mg/L)scored higher in overall aroma and fruitiness,which was significantly different from the other groups.By GC× GC-TOF-MS analysis,the result showed that the application of forchlorfenuron affected the type and content of aroma substances in oriental melon fruits,and there were significant differences between the various application concentrations.Meanwhile,the result showed that forchlorfenuron application at low concentrations decreased the total content of aroma substances in oriental melon compared to the control,whereas forchlorfenuron application at medium and high concentrations increased the total content of aroma substances in oriental melons.A total of 57 key difference substances were screened by combining multivariate statistical analysis,and ethyl acetate,amyl acetate,ethyl hexanoate,trans-2-nonenal,trans,cis-2,6-nonenal,and cis-6-nonenal were identified as key difference aroma active substances in combination with aroma threshold analysis.(4)Examine the effect of forchlorfenuron use on endogenous hormones in oriental melon to explore possible mechanisms of action.The application of forchlorfenuron,a cytokinin analog,resulted in significant changes in the content of endogenous hormones(cytokinin,growth hormone,gibberellin,abscisic acid,and jasmonic acid)in oriental melon fruits.It is hypothesized that the application of forchlorfenuron significantly affected the synthesis and metabolism of endogenous hormones in oriental melon,affecting the related metabolic pathways,which in turn led to changes in the content and types of related bitter and aromatic substances.