Determination of contents and components of water-soluble sugar in pear fruit by HPLC-ELSD

The contents of water-soluble sugars(fructose,sucrose,glucose and sorbitol)in different pear cultivars were investigated by HPLC.The working condition of HPLC was CAPCELL PAK NH2(4.6 mm×250 mm,5 μm)column,constant temperature of 50 ℃,and CH3CN and H2O with a volume ratio of 70∶30 as mobile phase.The sugar components could be precisely separated in 12 minutes at a flow rate of 1.0 mL·min-1 by an ELSD detector(the temperature of drift tube 80 ℃,nitrogen flow 2.0 mL·min-1).The recovery was 96.40%-103.20%.As shown in the results of 4 pear cultivars('Barlett','Huangguan','Houshui','Dangshansuli'),glucose,fructose,sucrose and sorbitol were the major water-soluble sugar in fruit.And among all sugar fractions determined in pear fruit,fructose predominated firstly(43%-66% of total sugar),then came sorbitol and glucose(about 13%-28% and 14%-18% of total sugar,respectively),and sucrose were at the least level,which was 4%-12% of total sugar.