Study On Changes Of Aroma Components And Fruit Quality Of Red Fragrant Pear During Storage

Red fragrant pear has good traits such as sweet and juicy,strong storability,and easy to bear fruit.It has been favored by growers and consumers and has a good development prospect in China.However,different storage periods have an important impact on the fruit quality of red fragrant pears.Maintaining fruit quality is the most critical issue in storage and freshness at present.Therefore,it is of great significance to study the quality changes of red fragrant pear during storage.In this paper,the aroma composition and fruit quality of red fragrant pear were studied in order to provide theoretical basis for the preservation of red fragrant pear.The specific research contents and results are as follows:(1)The aroma compounds in red fragrant pear were analyzed by headspace solid phase micro-extraction(HS-SPME)and gas chromatography-olfactometry-mass spectrometry(GC-O-MS).The extraction conditions of red fragrant pear were systematically optimized.An HP-5MS chromatographic column was chosen and 50/30 μm DVB/CAR/PDMS SPME fiber,2.9 g of sample,extraction time 46 min,temperature 64 ℃,equilibrium time 20 min and desorption time 4 min.The results showed that a total of 127 compounds were detected,76 compounds of which were structurally identified,accounting for 97.36 %of the total volatile substance.At the same time,the relative odor activity value(ROAV)was used to evaluate the contribution of characteristic aroma components in red fragrant pear.The results showed that esters and aldehydes were main aroma components of red fragrant pear.(2)A method of determination simultaneous six organic acids in red fragrant pear was built by high performance liquid chromatography.The chromatographic column used was CAPECELL PAK MG S5 C18(4.6mm×250 mm,5 μm);The mobile phase is 0.1 % H3PO4 and methanol(V:V=96 : 4)solution at a flow rate of 1 m L/min;The column temperature and detection wavelength were set as 40 ℃ and 210 nm,respectively.Under these conditions,D(+)-malic acid,L(+)-malic acid,tartaric acid,citric acid,succinic acid and lactic acid could be successfully separated in 20 minutes.All the calibration curves for these organic acids displayed a good linear relationship with correlation coefficients above 0.9999 and precision RSD of 0.32 %-2.64 %,stability RSD of 0.92 %-4.33 % and repeatability RSD of 0.66 %-3.07 %.The recovery rates of six organic acids were in the range of 96 %-105.42 %.A fluorescence analysis method was established to analyze the content of vitamin C in red fragrant pear.Under the conditions of laser wavelength of 340 nm and emission wavelength of 440 nm,the fluorescence intensity reached the maximum,and the correlation coefficient(R2)of the standard curve was 0.9986.The titration of 2,6dichloroindophenol was compared with fluorescence analysis.(3)The fruit quality and aroma compounds of red fragrant pear were evaluated during 0、45、90、120、150、180、210 days of storage.The results showed that the total organic content,firmness and Vc contents decreased,weight loss increased,SSC and ethylene production increased firstly and then decreased with the increasing storage time.Respiration rate was the highest at the 180 days.The proportion of aldehydes was higher in all aroma components,alcohol compounds gradually decreased and esters compounds increased firstly then decreased with increasing storage time,and the most obvious change is hexyl acetate,ɑ-farnesene was the predominant terpene volatile.