Accumulation And Utilization Of Active Aroma Compounds In Apple Fruit During Whole Growth Period

China as the world's apple planting and production of the country,the apple accounted for about 30%of China's fruit output.At present,apple producing areas in northwest China have developed rapidly,forming Xinjiang characteristic apple producing areas,Loess Plateau and other advantageous producing areas.At present,the apple cultivars in China are mainly late ripening varieties,and the proportion of middle and early ripening varieties is very low,which leads to a series of problems such as concentrated ripening of apples in the middle and late October,overproduction,and apple hoarding.In May each year,the waste of young fruit resources and environmental pollution caused by thinning fruit also need to be solved.Therefore,it is particularly important to explore the advantages of regional resources,expand the utilization of apple resources,reduce the hoarding of apple,and adhere to the sustainable development of apple industry.It is expected to alleviate the industrial pressure to explore the quality changes and processing potential of apple fruits at different growth stages.In this paper,the different growth periods of fruits were carried out to explore quality,especially for apple polyphenols and aroma change periodically analyzed detection.Apple's use of not only concentrated in the mature period,but from the young fruit period,expansion period,color conversion period,commercial maturity period,late harvest period and ice harvest period,respectively.The main results are as follows:1.The pH value of apple young fruit was between 3.27-3.86,the soluble solid content was between 7.9-9.6,and the total phenol content was between 4.93-9.00 g/L.the content of chlorogenic acid,phloridzin and epicatechin in monomer phenol was the highest,and the aroma was in the accumulation stage.Heat treatment is beneficial to the stability and maintenance of its color,and the sugar content is increased,while the acid content is decreased.SPME-GC-MS results showed that the aroma difference was greatly affected by varieties,and the contents of esters and terpenes decreased after heat treatment.The results of this study provide a scientific basis for the production of young fruit juice,and prove that young fruit juice has important value for the development of seasoning juice products.2.In this study,the changes of physicochemical indexes and aroma of apple fruit from young fruit period,expansion period,color conversion period and commercial maturity period were compared.The pH of the apple gradually decreased from 3.66 to 3.06 during the ripening period,and increased to 3.82 during the ripening period.The content of soluble solids increased from 8.00 oBrix at young fruit period to 15.05 oBrix at mature' period.The content of total phenol showed a decreasing trend from 7.30 g/L at young fruit period to 1.99 g/L at mature period.Chlorogenic acid and phloridzin were the main phenols in young fruit period,protocatechuic acid and chlorogenic acid were the main phenols in mature period.The total aroma concentration was the lowest in the expansion period and the highest in the mature period.The concentration of bound form aroma was higher than that of free form aroma in four periods.The release degree of bound form aroma was the largest in the expansion period,and the release potential of terpenoids was the highest.3.This study was to investigate the aroma profiles of late/ice harvest apples as well as their important phytochemicals in year 2018 and 2019.Apples were sampled every fifteen days from the commercial harvest day until the ice harvest.The results showed that the single fruit weight decreased,pH value increased and sugar content increased after late harvest.The content of polyphenols increased first and then decreased.The quantitative analysis by HS-SPME-GC-MS and following OAV analysis showed that most aroma compounds were observed increasing trends until the ice harvest,which indicated that late/ice harvest were believed conducive to aggregation of apple aroma.The content of aroma components in cider made from ice harvested apple was significantly higher than that in apple juice,and the kinds of esters and alcohols increased significantly.All of these findings provide a scientific basis for the characterization of the potential to brew ice cider from late/ice harvest of apple from the Loess Plateau area of China.In conclusion,based on the existing research on the apple industry,this paper further explored and improved the theoretical research on the fruit mature period,and established a theoretical basis for the future processing scale,comprehensive utilization rate of processing and sustainable development of the apple industry in China.