以坎下白桑、辽桑和慈山3个桑树品种为供试材料，6-9月间4次采样，以异硫氰酸苯酯为柱前衍生化试剂，采用反相高效液相色谱法测定桑叶游离氨基酸种类和含量。结果表明，桑叶中游离氨基酸总量和人体必需氨基酸总量，6月时分坎下白桑明显高于另外2个桑品种，7月分3个桑品种接近，8月分均降到较低水平，9月分均又回升并接近7月的水平。春季含量较高的丝氨酸到初霜时降低，春季含量较低的苏氨酸到初霜时升高。不同生长时期不同品种桑叶游离氨基酸种类和含量均有一定差别。%The mulberry leaves of Kanxiabai ,Liaosang and Cishan were collected four times between June and Sep-tember .Reversed-phase high performance liquid chromatography with precolumn Phenylisothiocyanate derivat-ization was used to analyze free amino acids type and content in mulberry leaves .The results showed that the to-tal free amino acid and total essential amino acid in Kanxiabai was higher than other two species in June ,but simi-lar in July ,and all down to a lower level in August ,in September rebounded close to the level in July .The con-tent of Serine was high in spring ,but decreased at first frost period .The content of Threonine was low in spring , and then increased at first frost period .The types and content of free amino acid in varieties of mulberry leaves at different growth periods were different .
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