Optimization Of Detection Methods For Polyphenols In Tomato Fruit And Comprehensive Evaluation Of Its Quality

In order to explore the quality difference of Tomato in different stages of development,9 tomato varieties were used as test materials,which were"han091"and"hanjiu",and"original flavor one","181","disease resistance 191","184","fanbeier 2","strawberry tomato"and"disease resistance 184"respectively,The results showed that the appearance of tomato fruit in different stages of development I（green stage）,Ⅱ（white ripening stage）,Ⅲ（color transition stage）,Ⅳ（mature stage）,Ⅴ（finishing stage）,and different parts（peel and pulp）were studied in the solar greenhouse of Qiyunshan National Garden complex,Chengguan Town,Yuzhong County,Lanzhou City,Gansu Province from October 2019 to April 2020 The difference of nutrition and flavor substances was made by using principal component analysis to evaluate the quality of 9 tomato varieties by selecting 40 indexes related to fruit quality in maturity.Meanwhile,the HPLC method for the content and components of polyphenols in tomato fruit was established.The feasibility of the method was investigated by linear relation,recovery,precision,stability and repeatability.The main results are as follows:1.A HPLC method for simultaneous determination of 16 polyphenols in tomato fruit was established.The method can rapidly separate 16 polyphenols in 60 minutes.The R2 of each polyphenol is in the range of 0.9989-0.9998.The linear relationship is good.The recovery rate is between 83%-103.41%.The coefficient of variation of each polyphenol peak area of precision,stability and repeatability is less than 10%.It shows that the method is fast,accurate,high precision Good stability.The chromatographic conditions were as follows:C18 column(250 mm 4×4.6 mm,5μm.Using methanol and 1%acetic acid as mobile phase,gradient elution was carried out,column temperature:30℃,flow rate:1.1 m L·min^-1,injection volume:10μL.Detection wavelength:240 nm to detect p-hydroxybenzoic acid,protocatechuic acid,quercetin,chlorogenic acid and rutin;Cinnamic acid,4-coumaric acid,gallic acid,naringenin,benzoic acid and ferulic acid were detected at 280 nm;Erucic acid,caffeic acid,artichodin,kaempferol and gentianic acid were detected at 322 nm.The optimal pretreatment method of tomato fruit was as follows:weigh 0.1 g dry powder,add 2 m L methanol,place at room temperature for 1 h,centrifuge at 4℃and 8000 rpm for 10 min,and then take the supernatant with 0.22 m L methanolμM membrane filtration after determination.2.The nutrients and flavor components（soluble sugar,organic acid and carotenoid）in the different development stages of tomato fruits of 9 varieties were the same.The soluble sugar was mainly composed of fructose,glucose and a small amount of sucrose.During the fruit development,the total change trend of soluble sugar components in different tomato fruit development stages was first increased and then decreased,citric acid content content of lycopene,β-carotene and total carotenoids increased first and then decreased.3.Among the 9 tomato varieties tested,the fruits are all oblate.There are significant differences in flavor substances of tomato fruit among different genotypes.Among them,the large-fruit type’Ham 091’and’Ham 9’have the lowest soluble sugar content,total flavonoids and lower total phenolic acid content,organic acid content,and carotenoids.The content of total soluble sugar in middle-fruit type’Fenbeier 2’is the highest,the content of total soluble sugar in“Strawberry Tomato”is the second,and the content of total carotenoids,total flavonoids and total phenolic acid of“Strawberry Tomato”is the highest.4.Among the 9 tomato varieties tested,the sugar acid ratio and lycopene content in different parts of the peel were higher than those in the pulp,and the contents of flavonoids and phenolic acids were different.Quercetin and rutin were the main components of tomato flavonoids,naringenin and kaempferol accounted for less than10%of total flavonoids,which could be ignored.The content of total flavonoids in peel was 0.86-2.2 times of that in pulp,and the content of total phenolic acids in peel was0.5-2.2 times of that in pulp.The main phenolic acids in pericarp were gallic acid,benzoic acid,gentian acid,chlorogenic acid and caffeic acid.Chlorogenic acid,gallic acid,gentian acid,caffeic acid and benzoic acid were the main phenolic acids in the pulp,while the other phenolic acids accounted for less than 10%of the total phenolic acids.5.For the 9 tomato varieties tested,40 quality traits related to appearance,nutrition,flavor,etc.were selected for principal component analysis.A total of 6 principal components were extracted,with a cumulative contribution rate of 90.57%,indicating that the first 6 principal components reflect 90.57%of the original information of 40quality indicators of tomato pulps.The contribution rate of the first principal component was 32.44%,which mainly included soluble solid,a*,aspect ratio,fructose,glucose,total soluble sugar,citric acid,total organic acid and p-hydroxybenzoic acid.The comprehensive rankings of the 9 tested tomato varieties are as following:’Strawberry Tomato’,’Fenbeier 2’,’184’,’181’,’DAnti-disease 184’,’Anti-disease 191’,’Original Flavor No.1’,’Hamm 9’,’Hamm 091’.Using cluster analysis based on the similarity of quality between varieties,9 tomato varieties can be divided into 3 categories:Category I has the best comprehensive quality,including’Strawberry Tomato’and’Fenbeier 2’;Category II has better comprehensive quality,including’181’and’184’;the third category includes’Yuanwei No.1’,’Anti-disease 191’,’Hamm 091’,’Anti-disease184’,’Hamm 9’,followed by comprehensive quality.