Abstract:

【Objective】 The characteristics of components and contents of soluble sugars in 98 cultivars of pear fruit were determined to reveal the differences and characteristics among different cultivars and species. 【Method】 The high performance liquid chromatography (HPLC) was used to detect the components and content of soluble sugar in mature pear fruits, and the data were analyzed by principal component analysis(PCs) and cluster analysis. 【Result】(1) The major components of soluble sugars in mature pear fruits were fructose, glucose, sucrose and sorbitol, and the fructose content was the highest value, with a mean of 51.17 mg?g-1FW. The contents of fructose and glucose were relatively stable among different cultivars, while the contents of sucrose and sorbitol varied greatly, the value ranged from 1.14-47.75 mg?g-1FW and 4.46-47.29 mg?g-1FW, respectively. (2) Among different species, the content of fructose was also the highest one, which accounted for 42.22%-57.02% of the value of total sugars, while the other three compoents of soluble sugars were highly different. The content of glucose was close to sorbitol in both P. bretschnrideri Rehd. and P. sinkiangensis Yü., and sucrose content was the lowest; the contents of fructose and sucrose were equal in both P. communis Linn. and P. ussuriensis Msxim. , however, the sorbitol content was high in P. communis Linn., and P. ussuriensis Msxim. in reverse; the content of sucrose was equal to sorbitol in P. pyrifolia Burm Nakai., and the glucose content was the lowest. (3) The distributive characteristics of soluble sugars in different species: P. bretschnrideri Rehd. mainly distributed in the high glucose and sorbitol area; P. pyrifolia Burm Nakai. mainly distributed in the high sucrose and sorbitol area; P.communis Linn. mainly distributed in high fructose and sorbitol area; P. ussuriensis Msxim. were mainly distributed in the high glucose and sucrose area; P. sinkiangensis Yü. mainly distributed in the high fructose and glucose area. 【Conclusion】 The major components of soluble sugars in pear fruits were fructose, glucose, sucrose and sorbitol, and the content of fructose was the highest one. The content of fructose and glucose kept stable among difference cultivars, while the content of sucrose and sorbitol showed high variability. Comparing different species, the content of fructose kept the highest value, while the other three components differ each other greatly. Based on the distribution of soluble sugars, P. bretschnrideri Rehd. classified as high glucose and sorbitol type, P. pyrifolia Burm Nakai. classified as high sucrose and sorbitol type, P. communis Linn. classified as high fructose and sorbitol type, P. ussuriensis Msxim. classified as high glucose and sucrose type, P. sinkiangensis Yü classified as high fructose and glucose type.

Key words: pear, fruits, soluble sugar, principal component analysis(PCs), cluster analysis