苯酚—硫酸法测定仁东大蒜中的总糖

Determination of Total Sugar in Ren-dong Garlic by Phenol-Sulfuric Acid Method

对大蒜总糖的提取条件进行优化,研究表明,6 mol/L提取剂盐酸的量为10.0 mL、加入蒸馏水15 mL、提取时间为30min沸水浴加热时为最佳提取条件。以葡萄糖为对照,采用苯酚-硫酸做为显色剂,对该法从检测波长、显色剂用量、显色时间、显色温度等方面进行最佳显色条件的研究。结果显示,最佳显色条件为精密吸取对照品溶液和供试品溶液0.2 mL,加蒸馏水至2.0 mL,加入浓度为5%苯酚1.0 mL,迅速滴加浓硫酸5.0 mL,室温25℃放置5 min后摇匀,沸水浴加热15 min,冷却至室温25℃,在最大吸收波长490 nm处测定吸光度。该方法的线性范围为5.05μg/mL^40.4μg/mL,标准溶液和试样的精密度RSD分别为1.58%和1.08%,加标回收率为95.74%~98.28%。该方法用于玉林仁东等9种不同产地的大蒜总糖含量的测定,得大蒜中总糖的含量为170.0 mg/g^220.0 mg/g。

The conditions of extraction of total sugar in garlic were optimized.The results show that the best extraction conditions were as follows,10.0 mL of 6 mol/L hydrochloric acid,15mL of distilled water and 30 min extracting time in boiling water bath.Taking glucose as reference substance,phenol-sulfuric acid reagent as chromogenic reagent,the optimum conditions for color reaction were studied by detecting wavelength,reagent dosage,time of color reaction and temperature of color reaction,etc.The results showed that the optimum conditions for color reaction were as follows,0.2 mL reference substance solution or sample solution was accurately drawn,then 2.0 mL of distilled water,1.0 mL of 5 % phenol solution was added in turn,and then 5.0 mL of concentrated sulfuric acid was dropped rapidly.The solution was shaked to homogeneity after being placed at room temperature 5 min.And then it was heated in water-bath for 15 min.Finally,it was cooled to room temperature.The absorbance was determine in the maximum absorption wavelength 490 nm.The linear range of the method is 5.05 μg/mL-40.4 μg/mL.RSD of standard solution and the the sample are 1.58 % and 1.08 %.The recovery of standard addition is 95.74 %-98.28 %.This method had been applied to the determination of total sugar content in nine different garlic originating from Yulin-rendong.It has been proved that the total sugar content of these garlisc is 170.0 mg/g-220.0 mg/g.