Organic Acid Composition in the Pulp of Loquat (Eriobotrya japonica Lindl.) and Distribution in Fruits
枇杷果肉有机酸组分及有机酸在果实内的分布

Organic acids from the ripe pulp of 18 loquat (Eriobotrya japonica Lindl.) cultivars ('Xiaomaopipa','Jiajiao', 'Zhuonan 1', 'Jiefangzhong', 'Fuyang', 'Moriowase', 'Huabao 2', 'Xiangzhong 10', 'Baihua','Toi', 'Duobao 2', 'Wugongbai', 'Luoyangchin', 'Mogi', 'Zaozhong 6', 'Ba ili', 'Tantou 4', 'Changhong3') and their distribution in the ripe fruit of 2 cultivars ('Jiefangzhong' and 'Zaozhong 6' ) were determined byhigh-performance ion-exchange chromatography (HPIC). Eight organic acids (malic, quinic, citric, iso-citric, α-ketoglutaric, fumaric, oxaloacetic and tartaric acids) were identified in ripe pulp, while trace quantities of ferulic,cis-aconitic and β-coumaric acids were identified in several cultivars. The predominant organic acid of ripe pulp ofmost cultivars was malic acid, with an average content of 4 399 mg kg-1 FW for all cultivars, accounting for62.7% of the total acids. Quinic acid was the second in abundance, with an average content of 2 042 mg kg-1 FW,accounting for 29.1% of the total acids. Other acids ranged from trace to 3.0% of the total acids. Considerablevariations in titratable acidity and organic acid content exist among cultivars. Based on titratable acidity, 18 culti-vars could be separated into 5 groups by clustering analysis: very high acidity ('Xiaomaopipa'), high acidity('Jiajiao', 'Zhuonan 1 ', 'Jiefangzhong' and 'Fuyang' ), medium acidity ('Moriowase', 'Huabao 2', 'Xiang-zhong 10', 'Baihua', 'Toi', 'Duobao 2 '), low acidity ('Wugongbai', 'Luoyangchin ', 'Mogi' and 'Zaozhong 6' ), and very low acidity ('Baili', 'Tantou 4' and 'Changhong 3' ). No significant difference wasfound in the absolute amounts of total acids and titratable acidity between pulp and skins, while the amounts of to-tal acids and titratable acidity in seeds was far lower than those in pulp and skins. The major organic acids identi-fied in skins and seeds were malic and quinic acids. In skins, the content of malic acid was far higher than quinicacid, but in seeds it was slightly lower than quinic acid. In addition, malic acid and quinic acid content in seedswas far lower than those in pulp and skins.