Comparation of fruit quality and aroma components among three redskinned sand pear varieties

Abstract: 【Objective】Meirensu, Mantianhong and Caiyunhong are the main red-skinned pear varieties in Yunnan province. The fruit appearance characteristics, nutritional values and aroma components of three red-skinned pear varieties were compared and analyzed in order to provide theoretical basis for the research on fruit quality, breeding and introduction of new red-skinned pear varieties.【Methods】 Using the fruits of Meirensu, Mantianhong and Caiyunhong as materials, the single fruit weight, firm-ness, soluble solids, titratable acid, vitamin C, sugar and acid components were detected. The content of phenols was determined by UPLC-PDA-MS/MS-ESI. HS-SPME and GC-MS were used to determine aroma components and relative content in red-skinned pears.【Results】The single fruit weight, firm-ness and vitamin C contents of Mantianhong were higher than those of Caiyunhong and Meirensu. The fruit shape index of Meirensu was higher than that of Caiyunhong and Mantianhong. The shape of Mei-rensu was oval, but that of Caiyunhong and Mantianhong was ellipse. After 10 days of storage, the firm-ness of all the fruits decreased, but the order of firmness in fruits remained unchanged as before. The content of vitamin C in Mantianhong pear decreased, while that of Caiyunhong and Meirensu increased.The soluble solid content of Caiyunhong was significantly higher than that of Mantianhong and Meiren-su.Meanwhile, the titratable acid content in Caiyunhong was at the lowest level among three redskinned pear varieties. The solid/acid ratio of Caiyunhong was 100.74, which was higher than that of  Meirensu and Mantianhong by 3.01 times and 2.38 times, respectively. The solid/acid ratio in pears indi-cated that the taste of Caiyunhong was sweet, while that of Mantianhong and Meirensu was sour. After 10 days shelf life, the soluble solid content of all pears increased, while the titratable acid content de-creased, the solid/acid ratio and the sweetness increased. Contents of soluble solids, total polyphenols,total flavonoids and total anthocyanins of Caiyunhong were higher than those of Meirensu and Mantian-hong. After 10 days of storage, the contents of total flavonoids, polyphenols and anthocyanins of Cai-yunhong and Mantianhong decreased, while the contents of Meirensu increased. The contents of total sugar, sorbitol and sucrose of Caiyunhong pear before and after storage were significantly higher than those of Meirensu and Mantianhong. The glucose content in Meirensu was higher than that in Caiyun-hong and Mantianhong. The fructose content of Mantianhong was higher than that of Meirensu and Cai-yunhong. After 10 days of storage, the contents of total sugar and sucrose increased, while the content of sorbitol decreased. The contents of total acid and quinic acid in Mantianhong were significantly high-er than those in Meirensu and Caiyunhong. Meirensu was rich in citric acid, while Caiyunhong was rich in quinic, malic and shikimic acids. After 10 days storage, the total acid content of all pear varieties decreased. 35 kinds of aroma compounds were detected in Meirensu, among which there were 7 alde-hydes (relative content 14.72% ), 13 alcohols (relative content 36.16% ), 3 esters (relative content 5.67%), 3 ketones (relative content 18.13%), 6 acids (relative content 20.41%), 1 terpene (relative con-tent 1.48%) and 2 other compounds (relative content 3.43%). Mantianhong contained 34 kinds of aroma compounds, including 8 aldehydes (18.10% ), 13 alcohols (38.04% ), 3 esters (10.02% ), 3 ketones (9.72% ), 5 acids (21.01% ) and 2 terpenes (3.12% ). Caiyunhong contained 47 kinds of aroma com-pounds, including 10 aldehydes (13.28% ), 14 alcohols (36.34% ), 9 esters (18.99% ), 5 ketones (17.00%), 4 acids (6.49%), 1 terpene (4.30%) and 4 other compounds (3.61%). Among them, 23 kinds of aroma compounds were detected in all three pear varieties.【Conclusion】The solid/acid ratio of Cai-yunhong pear was significantly higher than that of Meirensu and Mantianhong, and had the highest lev-el of sweetness. Fructose was the main sugar component, while malic and citric acids were the main ac-id components. The contents of total flavonoids, polyphenols and anthocyanins of Caiyunhong pear were higher than those of Meirensu and Mantianhong, but storage period had a great effect on the con-tent of phenols in Caiyunhong fruit. The alcohol substances were the most abundant aroma in the pear fruits. Based on the comprehensive evaluation results of sensory evaluation, nutrients and flavor sub- stances, Caiyunhong pear could be used as a reference variety for the breeding of red-skinned sand pear varieties, and was an excellent variety in red sand pear varieties for large-scale growing.