Study On The Components During Gannan Navel Orange Growth Based On Chromatography-mass Spectrometry Technology

Gannan navel orange is called "king of Citrus" and is one of the most distinctive agricultural products in Jiangxi Province.Navel orange is one of the most consumed fruit crops in the world and is a good fruit product because of its delicious appearance,strong flavor and sweet taste.Navel orange is rich in nutrition,contains essential oil,flavonoids,carotenoids,phenolic acid,citrinin,vitamins,and other beneficial chemical components.It has physiological functions of anti-cancer,anti-oxidation,antiinflammatory,anti mutation,cholesterol lowering and immunity regulation.The accumulation of navel orange composition is a dynamic process,its properties and content will change with varieties,storage conditions,agricultural growth environment,maturity,etc.So far,a lot of researches have been done on the extraction,physiological activities and variety difference of navel orange at home and abroad,but the research on the dynamic change of navel orange is not very deep.Therefore,the study focus on the changes of volatile and non-volatile components during navel orange growth,and the distribution of dynamic components by means of chromatography-mass spectrometry and chemometrics analysis technology,and the variation trend of navel orange components during ripening process was found out.The main findings are as follows:(1)The research results on chemical constituents,physiological activities and analysis methods of Gannan navel orange in recent years at home and abroad were described in detail.Navel orange fruit is rich in nutritional value,which not only contains a large number of volatile components such as terpenes,aldehydes,esters and other flavor components,but also rich in active components beneficial to body health,such as flavonoids,phenolic acids,amino acids,etc.In addition,the application of stoichiometry and chromatography-mass spectrometry in the analysis of citrus components was discussed.(2)This study investigated the changes in volatile organic compounds(VOCs)of navel orange during fruit maturation.The volatiles in navel orange from July(young fruit period)to November(commercial maturation period)were separated by headspace solid-phase microextraction(HS-SPME)and analyzed using gas chromatography–mass spectrometry(GC–MS).Fifty-seven VOCs were identified and classified into five groups.Through principal component analysis,the samples of different months were discriminated,and one-way analysis of variance showed that 55 volatiles significantly differed during growth.Among the VOCs,the relative concentration of monoterpenes increased with maturity,and D-limonene was the component with the highest content.Similar behavior was exhibited for aldehydes,reaching the maximum content in November.On the contrary,esters decreased its concentration from July to November.The concentration of sesquiterpenes gradually increased,reaching the maximum level between August and November.Moreover,alcohols reached theirs largest content in September,β-Linalool had the highest content among the alcohols.These results provided important theoretical support for the development of navel orange components and comprehensively elucidate the flavor characteristics during the ripening of navel orange.(3)The non-volatile compounds of Gannan navel orange pulp were determined by UPLC-TOF-MS in different growth months.A total of 67 non-volatile active compounds were identified during navel orange ripening.Principal component analysis(PCA)was used to distinguish navel oranges with different maturity,and partial least square discriminant analysis and one-way analysis of variance were used to find out the differential components during navel oranges growth months.A total of 17 kinds of differential metabolites were inferred,and the content changes of the differential components were analyzed.Among them,the content of flavonoid compounds decreased first and then increased with the increase of maturity,and the content was the lowest in the semi-mature stage.The results of clustering correlation analysis were consistent with those of principal component analysis.These results laid a foundation for further study on the metabolic mechanism of differential components during navel orange growth.(4)Ripe navel orange has abundant amounts of phenolic compounds.Few studies monitored changes in these compounds during ripening.In this study,the effects of navel orange maturation on dynamic changes in antioxidant activity,total phenolic content(TPC),total flavonoid content(TFC)and phenolic acids were investigated.Five growth stages of navel orange were studied,and nine phenolic acids were detected via high performance liquid chromatography–triple quadrupole mass spectrometry(HPLC–QQQ–MS).Results showed that antioxidant activity,TFC and TPC decreased gradually with fruit ripening.The concentrations of most phenolic acids also declined during fruit maturation,except for free fractions of sinapic acid and bound fractions of ferulic and caffeic acids.Ferulic acid was the most dominant in all phenolic acids at all growth stages.Partial least-squares showed significant differences among fruits of different maturities.A significant correlation between antioxidant capacity,TPC,TFC and some phenolic acids was found.