| Water-soluble sugar-acid ratio in strawberry is an important factor affecting fruit quality.Antioxidant substances are important indicators to evaluate the nutritional and health value of fruit.Aromatic compounds also play an important role in the flavor of strawberry fruit.Through the analysis of nutritional quality and aroma components of sugar and ellagic acid in 50 strawberry varieties at different growth and development stages,the dominant varieties in soluble solids,antioxidant activity and aroma were preliminarily screened,and the accumulation patterns of ellagic acid and aroma substances were analyzed,which laid a foundation for further exploring the formation mechanism of ellagic acid and aroma substances,as well as for hybrid breeding fathers.Maternal selection provides guidance.The soluble solids content of 50 strawberry varieties in germplasm resource nursery was studied and analyzed in this experiment.The content of ellagic acid in strawberry fruit was determined by high performance liquid chromatography(LC);the content of free ellagic acid in 50 cultivars at maturity stage was compared and analyzed;three main Japanese cultivars ’Benihoppe’,’Taoxun’,’Suizhu’ and three self-selected prepopularized cultivars’Xiaobai’,’Yanli’,’Snow white’ were selected for different growth and development.The change trend of free ellagic acid content in fruits during the period.The volatile components of the six strawberry cultivars were analyzed by GC-MS using organic solvent extraction and headspace solid-phase microextraction.The differences of characteristic aroma components between the two extraction schemes were summarized and analyzed,and the change rule of strawberry aroma components during strawberry ripening was analyzed.The results are as follows:1.The range of soluble solids in 50 strawberry varieties at maturity stage was 5.02%-11.32%.There are four varieties with SSC content over 10%in mature period:’Wanxiang’,’Snow white’,’Buji’ and‘Christmas red’.The content of soluble solids in’Wanxiang’ was the highest at maturity stage,followed by ’Snow white’.The SSC content of ’Benihoppe’,a Japanese strawberry cultivar grown in China,was 8.78%,slightly lower than that of the former.2.The determination method of ellagic acid was optimized,and the content of free ellagic acid in 50 strawberry varieties at maturity was determined and compared.The results showed that the content of free ellagic acid in strawberry fruits ranged from 135.20μg/100g to 909.55 μg/100g at ripening stage.The five strawberry varieties with the highest content ’Xiaobai’,’Chunyou’,’Buji’,’Shenyang’,’Tianxiang’ were all Self-bred in China,which indicated that the self-bred varieties in China had certain advantages in ellagic acid content.In addition,the change patterns of fruit development of six strawberry varieties were determined.The content of ellagic acid in two Japanese varieties ’Benihoppe’ and ’Suizhu’ decreased rapidly from big green fruit stage to white fruit stage,and the change trend was not obvious from white fruit stage to mature stage;the content of ’Taoxun’,’Xiaobai’ and ’Yanli’ ellagic acid decreased first and then increased with fruit ripening.Trend:The content of ellagic acid fluctuated greatly during the fruit development of ’Snow white’,which was higher in the big green fruit stage and the color changing stage,but lower in the white fruit stage and the mature stage.The highest content of ellagic acid was ’Xiaobai’(909.55 μg/100g),the lowest was ’Suizhu’(189.04μg/100g),and the main strawberry cultivar ’Benihoppe’(270.77μg/100g)at maturity.3.The aroma compounds of six strawberry varieties at four growth stages were extracted by organic solvent extraction and SH-SPME methods for GC-MS analysis.The volatile alkanes detected by organic solvent extraction method were the most abundant and the highest content;SH-SPME extraction method found that the aldehydes content was the highest from the big green fruit stage to the turning color stage,and the esters accumulated continuously during the fruit ripening process,and reached the maximum value at the ripening stage to become the highest content of aroma components.4.There are 13 aromatic substances whose relative content is more than 1%in the mature stage of ’Benihoppe’.The content of ethyl caproate is the highest in esters,and ethyl butyrate is the unique component of ’Benihoppe’.The contents of alool and nerolic tertiary alcohol were 13.76%and 8.10%respectively.It was speculated that the aroma of’Benihoppe’ was the result of the interaction of aroma esters and aroma alcohols.There were 14 kinds of aroma substances whose volatile content was more than 1%in ’Yanli’.The highest content of esters was methyl caproate,alool was one of the main characteristic aroma substances,and the unique content of a-terpineol in ’Yanli’ was 1.41%.Three kinds of furanones were detected,the relative content of DMMF was 5.64%,and the content of y-decanolide was prominent,which was the main substance of’Yanli’ fragrance;(Z)-3-hexene-1-alcohol-acetate(30.76%),(4E)-4-hexene-1-ol acetate(1.39%)and 9-methyl-1-decanol(2.91%)in ’Snow white’ fragrance components were unique to the other five varieties;(Z)-3-hexene-1-alcohol-acetate(3.76%)was volatile in ’Taoxun’.There are 13 kinds of aromatic substances whose content is more than 1%.Esters are different from other strawberry varieties in aromatic substances:decanoic acid,octyl acetate,octyl 3-methyl-butyrate,octyl formate,octyl hexanoate and ethyl octanate.Ethyl caproate with 28.13%content was the highest in esters,and the content of esters was higher than 70%,(E)-2-hexenal(3.67%)was the lowest in six strawberry cultivars;the content of linalool was the highest in the substances with more than 1%content of volatile substances in ’Suizhu’,followed by(Z)-2-hexene-1-alcohol-acetate;the relative content of ’Xiaobai’ was higher than 1%in mature stage.There are 13 characteristic aromatic substances,the highest content of esters is methyl caproate,the highest content of aromatic alcohol is alool,the highest content of 26.70%green folial aldehyde is in the mature fruit of six strawberry varieties,decanal is the unique aldehyde substance of’Xiaobai’,monoterpene compound D-citrone may be an important component of the characteristic aroma of ’Xiaobai’. |
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