桑叶植酸的提取条件优化及桑叶和蚕粪中的植酸含量检测

Optimization of Extraction Condition for Phytic Acid from Mulberry Leaf and Determination of Phytic Acid Contents in Mulberry Leaf and Silkworm Excrement

建立高效提取桑叶植酸的方法,并应用于检测分析不同品种、不同成熟度桑叶中的植酸含量和蚕粪中的植酸含量,有助于进一步开展降低桑叶中的植酸含量及提高桑叶营养利用率的研究。运用Design-Expert 8.0.4 Trial软件的Box-Behnken模型,分析不同提取条件因子对桑叶植酸提取效果的影响作用为原料质量浓度>提取液中盐酸的浓度>浸提时间,确定最佳提取条件:提取液为1.25%盐酸+0.1 g/mL硫酸钠,浸提时间为2.18 h,原料质量浓度为0.05 g/mL。在此优化条件下提取桑叶和蚕粪中的植酸,并应用比色法测定5个桑品种春季成熟叶、嫩叶以及秋季成熟叶、嫩叶中的植酸平均质量比分别为3.98、3.55、3.75、3.52 mg/g,5龄幼虫蚕粪中的植酸含量为3.78 mg/g,与桑叶中的植酸含量接近。检测结果说明桑叶中的植酸随着桑叶的成熟其含量不断增加,家蚕不能吸收利用植酸态的磷。

The establishment of extraction protocol for phytic acid from mulberry leaf and its application of the method for determining phytic acid contents in mulberry leaves of different varieties and different maturities and in silkworm excrement would promote further studies on reducing phytic acid content in mulberry leaves and improving their nutrient utilization rate.In this study,we analyzed effect of different extraction conditions and factors on the yield of phytic acid from mulberry leaves by means of Box-Behnken model of the Design-Expert 8.0.4 Trial software.The results showed that the effective factors for phytic acid extraction were in the order of raw material mass concentration,hydrochloric acid concentration in the extraction solution,and extraction time.The optimum extraction condition was as follows： 1.25% hydrochloric acid and 0.1 g/mL sodium sulfate in extraction solution,extraction time 2.18 h,and raw material mass concentration 0.05 g/mL.Based on this optimum condition,we extracted phytic acid from mulberry leaves and silkworm excrement and used colorimetric method to determine phytic acid contents in mulberry leaves of different maturities of 5 mulberry varieties.It was found that the average phytic acid content was 3.98 mg/g in spring mature leaves,3.55 mg/g in spring tender leaves,3.75 mg/g in autumnal mature leaves,and 3.52 mg/g in autumnal tender leaves,respectively.Meanwhile,the phytic acid content in silkworm excrement of the 5th instar silkworm larvae was 3.78 mg/g,being close to that in mulberry leaves.These results showed that phytic acid content in mulberry leaves increased steadily with the maturity of mulberry leaves,and silkworm larvae could not absorb and utilize phosphorus in the form of phytic acid.