Studies On Volatile Compounds Of Different Apple Fruit Cultivars

Apple is a major fruit crop with the highest market demand because of good taste,high nutritional properties and storability.The consumer preference is depend on texture and flavour of fruits and is a fundamental factor to build up the market demand.The taste of fruit was controlled by organic acids,aromatic volatile compounds and soluble sugars,which strongly facilitate overall organoleptic quality and fruit stability.Aromatic volatile production increases during fruit ripening,through crop domestication and classical breeding.Aroma compounds synthesis is very intricate and are influenced by many pre-and post-harvest factors.Mostly post-harvest technologies are focused only on the appearance,decay resistance of fruits and have often neglected flavour and sensory quality.In order to reduce loss of flavour in fruits,a deeper knowledge of the initial VOCs composition with the relative cultivars is required.The ripe apple(Malus x domestica Borkh)produced aroma from a complex mixture of over 350 volatile compounds including esters,alcohols,aldehydes,ketone and sesquiterpenes.In the present study,E-nose and HS-SPME-GC-MS were used to study the fruit’s aroma composition in different cultivars of apple.The entire apple aromatics of 194 apple accessions,including the most popular cultivars of 59 ’Fuji’,20 ’Golden delicious’,5 ’Wild haitang’ and 110 other cultivars.The total of 32 volatile compounds,such as 12 ester,8 alcohols,7 aldehydes,1 terpenoid,2 ketones,and 2 acids,etc.,were identified.From which,three specific apple series(Fuji,Golden Delicious,wild haitang)were used for further analysis and selected the most abundant 10 distinctive compounds for HCA(Hierarchical cluster analysis)to better represent their aroma profiles.The clustering result was also in agreement with these specific 10 compounds were more closely link with’Fuji’ series like the results of E-nose and GC-MS data and all ’Fuji’ series was positively correlated and contained higher concentration of major aroma compounds compared with ’Golden delicious’ and’Wild haitang’ series.The aroma composition for ’Golden delicious’ and ’Wild haitang’ series were nearly the same.Results showed that hexanal,1-hexanol,(E)-2-hexanal,butyl acetate,hexyl acetate,2-methylbutyl acetate,butyl 2-methylbutyrate,and hexyl-2-methylbutyrate were represented the major components of aroma compounds in apple fruits.In addition,we also studied about the compositions of different volatile compounds for different fruit size of apples.Four groups(small,medium,big,too big)were separated for this research.Ester compounds were highly detected from medium size of fruits than the other three groups;especially small and too big size of fruits were low correlated with ester compounds due to their cell packing.According to this result,the aroma composition was also depends on fruit size and highly composition in fruit with a size between 200-300 g.Taken together,this study suggests that although the compositions of aroma compounds varied among different cultivars,the differences within their relative accessions were not too much varied.Although the compositions of aroma compounds varied with different cultivars,the specific aroma profile was the same especially in ’Fuji’ series.In addition,the aroma compounds composition for apple is likely to be associated with the fruit size especially for ester compounds.However,optimization of treatment method,storage conditions and finding the gene expression impact on apple aroma are necessary for successful implementation in commercial industry.