枇杷果肉有机酸组分及有机酸在果实内的分布

Organic Acid Composition in the Pulp of Loquat (Eriobotrya japonica Lindl.) and Distribution in Fruits

摘要:

用高效离子交换色谱(HPIC)测定了枇杷(Eriobotrya japonica Lindl.)18个品种(小毛枇杷、夹脚、卓南1号、解放钟、富阳、森尾早生、华宝2号、香钟10号、白花、土肥、多宝2号、乌躬白、洛阳青、茂木、早钟6号、白梨、塘头4号和长红3号)的成熟果肉和2个品种(解放钟和早钟6号果)成熟果实不同组织有机酸含量。结果表明，成熟果肉中均含有苹果酸、奎尼酸、柠檬酸、异柠檬酸、α-酮戊二酸、富马酸、草酰乙酸、酒石酸8种有机酸，有的还含有微量的阿魏酸、顺乌头酸和β-香豆酸。大多数品种果肉中苹果酸含量最高，平均含量为4 399 mg kg-1 FW，占总酸的 62.7%；其次是奎尼酸，其平均含量为2 042 mg kg-1 FW，占总酸的29.1%。品种之间可滴定酸和有机酸含量差异很大。通过对果肉可滴定酸进行聚类分析，可把18个枇杷品种分为五个组群：极高酸(小毛枇杷)、高酸(夹脚、卓南1号、解放钟和富阳)、中酸(森尾早生、华宝2号、香钟10号、白花、土肥和多宝2号)、低酸(乌躬白、洛阳青、茂木和早钟6号)和极低酸(白梨、塘头4号和长红3号)。解放钟和早钟6号果肉和果皮的总酸含量及可滴定酸均无显著差异，但果皮和果肉的总酸含量和可滴定酸均大大高于种子。相似于果肉，果皮和种子的主要有机酸也是苹果酸和奎尼酸。果皮中苹果酸含量远高于奎尼酸，但种子中苹果酸含量比奎尼酸稍低。此外，种子中苹果酸和奎尼酸比果肉和果皮中的低得多。

Abstract:

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’, ‘Baili’, ‘Tantou 4’, ‘Changhong 3’) and their distribution in the ripe fruit of 2 cultivars (‘Jiefangzhong’ and ‘Zaozhong 6’) were determined by high-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 of most cultivars was malic acid, with an average content of 4 399 mg kg-1 FW for all cultivars, accounting for 62.7% to 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% to the total acids. Other acids ranged from trace to 3.0% of the total acids. Considerable variations in titratable acidity and organic acid content exist among cultivars. Based on titratable acidity, 18 cultivars 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’, ‘Xiangzhong 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 was found in the absolute amounts of total acids and titratable acidity between pulp and skins, while the amounts of total acids and titratable acidity in seeds was far lower than those in pulp and skins. The major organic acids identified in skins and seeds were malic and quinic acids. In skins, the content of malic acid was far higher than quinic acid, but in seeds it was slightly lower than quinic acid. In addition, malic acid and quinic acid content in seeds was far lower than those in pulp and skins.