不同龙眼品种果实品质和糖酸组分分析

Analysis of fruit sugar and acid compositions in the aril of different longan cultivars

以12个龙眼品种的果实为试材,利用常规的品质分析和高效液相色谱技术,进行了果实品质和糖酸组分分析。结果表明,品种间果实质量和可溶性固形物含量差异较大,分别为6.1～15.1g和12.2%～23.0%。可食率最高为双孖木(71.4%),最低为沙梨木(56.2%)。果糖、葡萄糖和蔗糖是龙眼假种皮的主要糖类,但不同品种这3种糖的比例有较大差异,根据单糖与双糖的比例,可将不同的龙眼品种分为3个类型:蔗糖积累型,还原糖积累型和中间类型。龙眼假种皮中的有机酸含量较低,为1.46～3.46mg/g,主要有苹果酸、草酰乙酸、α-酮戊二酸、草酸、柠檬酸、酒石酸和奎尼酸,不同品种有机酸的含量和比例有一定的差异。龙眼假种皮中也有较丰富的还原型抗坏血酸(维生素C),约占总酸的12.4%,不同品种维生素C含量有较大差异,储良最低(0.13mg/g),罗伞木最高(0.65mg/g)。

Fruits of 12 longan （Dimocarpus longan Lour.） cultivars grown in Guangdong and Fujian provinces were used as materials for studying the fruit quality and sugar and acid compositions in aril. Results showed that the fruit weight, content of total soluble solids and edible pulp rate of tested cultivars ranged from 6.1 to 15.1 g, 12.2 to 23.0% and 56.2 to 71.4% respectively. Fructose, glucose and sucrose were the predominant sugars in the aril. Different cultivars showed remarkable difference in the sugar compositions. They could be classified into 3 types based on their sugar composition： 1） Sucrose prevalent type, including cvs. Shuangmamu, Zihuamu, Chuliang and Shalimu, contained more sucrose than monosaccharides （fructose and glucose） ; 2） Monosaccharide prevalent type, including cvs. Hualuguangyan and Luosanmu, accumulated more monosaccharides than sucrose; and 3） Intermediate type, including cvs. Shixia, Dongbi, Shuiyan, Honghe, Jimaoyan and Zaoshulhao. The organic acids in the aril ranged from 1.46 to 3.46 mg/g and the main acids were malic acid, oxaloacetic acid, α-ketoglutaric acid, oxalic acid, citric acid, tartaric acid and quinic acid. There was a relative high content of reduced ascorbic acid （vitamin C）（12.4% of total acids） in the aril. It was the lowest in cultivar Chuliang （0.13 mg/g） and highest in Luosanmu （0.65 mg/g）.