Research Of Exterior Quality Index And Aroma Components Detection In Persimmon (Diospyros Kaki Lindl.)Fruit

Persimmon (Diospyros kaki Lindl.) is originated from China with about 3000 years of cultivation history in our country. People love persimmon because of its fruit with bright color, unique flavor and various nutritions. The researches on persimmon fruit are mainly focused on tannis and postharvest storage, with few concerned to fruit aroma. In this study, we used persimmon fruits as materials, and analyzed the fruit aroma of different cultivars and different developmental stages of the persimmon with SPME-GC-MS based on the basic quality index and color index determination. The main results were as follows:1. We determined the basic quality index and color index of persimmon fruits of 34 varieties at mature stage. The results showed that the average level of fruit shape index, TSS of astringent persimmons are higher than those of sweet persimmons, but the average value of fruit weight, transverse diameter, hardness and seed number of sweet persimmons are higher than astringent persimmons, the average value of the vertical diameter and TA content is similar in astringent and sweet persimmons. Color difference analysis showed that the peel color of astringent persimmons were more closed to red compared to the sweet persimmons, the pulp color of astringent persimmons were more closed to yellow compared to the sweet persimmons on the whole.We determined the main fruit quality indices of persimmon fruit cv.’Xiaofangshi’ and ’Naiyoushi’ during different development stages. The results showed that the single weight, transverse diameter, vertical diameter and TSS of persimmon fruit cv. ’Xiaofangshi’ and ’Naiyoushi’ showed a trend of increase from 26 August to 23 September but the hardness and TA value showed a trend of decrease. The single fruit weight, transverse diameter, vertical diameter of ’Naiyushi’ were higher than ’Xiaofangshi’ during development period. TSS of ’Xiaofangshi’ and ’Naiyoushi’ both showed a trend of increase during the time from 10 September to 17 September, but the value of TSS of ’Naiyoushi’ was higher than ’Xiaofangshi’ at 10 September. There was little difference in peel and flesh color of persimmon fruit cv.’Xiaofangshi’ and ’Naiyoushi’ during different development period, but the color of ’Xiaofangshi’ were more closed to red than ’Naiyoushi’ from 17 September.2. We detected persimmon fruit aroma by gas chromatography-mass spectrometry (GC-MS). Fruits of’Xiaofangshi’at mature stage were used as test materials, orthogonal experiment analysis was done based on the single factor experiment including extraction temperature, extraction time and sample amount. The results show that the optimum extraction conditions for persimmon aroma is extraction temperature of 50 "C, extraction time for 40 min, sample amount of 8 ml.The aroma composition of whole persimmon fruit is rich to flesh by detecting persimmon fruits of 34 different varieties at mature stage. But the highest relative content both are alcohols no matter in whole fruit or flesh, aldehydes and esters followed in sweet persimmon varieties, while esters and aldehydes followed in astringent persimmon varieties. The aroma composition and relative content in whole fruit and flesh is not the same, but the relative contents of 2-hexene aldehyde,2-ethyl-l-hexanol and hexanal are much higher both in whole fruit and flesh of 8 sweet persimmon varieties. However, in whole fruit and flesh of 26 astringent persimmon varieties, the relative contents of 2-hexene aldehyde, ethyl acetate and butyl acetate are much higher.3. We determined the aroma composition of persimmon fruit cv.’Xiaofangshi’and ’Naiyoushi’during development period. The results showed that aroma composition species showed a tendency of decrease after increase. The aroma compositions appeared peak in 10 September except 2 September for ’Naiyoushi’. The aroma type in whole fruit is far more abundant than in flesh, but the specific component content is not the same.We also analysis apocarotenoids in persimmon fruit cv.’Xiaofangshi’ and ’Naiyoushi’ during development period. The results showed that two kinds of apocarotenoids ’6-methyl-5-heptene-2-keto’and’beta ionone’were identified by database analysis. The change tendency of them is not obvious. However, We found the highest content of beta ionone in S2 stage in whole fruit and flesh of’Xiaofangshi’, with the value of 5.80 μg/g and 5.69 μg/g, respecticely. The highest content of beta ionone in S3 stage in whole fruit and pulp of ’Naiyoushi’, with the value of 5.09 μg/g and 6.37 μg/g, respectively.