响应面法对3,5-二硝基水杨酸比色法测定水果中还原糖含量条件的优化

Optimization of 3,5-Dinitrosalicylic Acid Colorimetry Determination Conditions of Reducing Sugar in Fruits by Response Surface Method

采用3,5-二硝基水杨酸(DNS)比色法测定水果中还原糖的含量,在单因素试验的基础上,采用三因素三水平的响应面分析法(RSM)优化DNS法测定苹果还原糖的最佳条件,同时建立数学模型并验证其可靠性。回归方程失拟项不显著(P=0.133 7),预测值与实际值吻合(R^2=0.957 4);影响DNS法测定还原糖含量的因素主次顺序为:DNS用量﹥反应温度﹥显色时间;DNS法测定还原糖含量的最佳条件为:DNS用量4.0 m L,显色时间5.0 min,反应温度87.0℃,测得还原糖实际浓度为94.66 mg/L,与理论预测值基本相符。按照优化的最佳条件,以苹果、桃、葡萄、哈密瓜、脐橙、菠萝6种代表性水果为对象验证该方法的精密度、重复性和准确度,其标准偏差为0.1%~0.5%,相对标准偏差为2.0%~4.8%,加标回收率为90.6%~104.2%。该方法简便、快速,准确度高,重现性好,适合于苹果及其他水果中还原糖的测定。

The optimum reducing sugar determination conditions of 3, 5-dinitrosalicylic acid colori- metry（DNS colorimetry） were investigated using the Response Surface Method（RSM）. The reducing sugar content in apple was obtained under the optimum extraction conditions. Based on the results of the single factor experiments, an optimization procedure was carried out in order to investigate the effects of key parameters on reducing sugar determination. Optimization was conducted using a Cen- tral Composite Design（CCD） with three key factors of DNS amount, reaction temperature and colora- tion time. The quadratic term model of the determination conditions was established and the reliability was checked. The results of regression analysis presented a non-significant lack of fit（P = 0. 133 7） and a high coefficient of determination value （ R2 ） of 0. 957 4 for the response surface model, which showed a satisfactory agreement of the polynomial regression equation with experimental data. The in- fluence of three factors followed the sequence as ： DNS amount 〉 reaction temperature 〉 coloration time. The optimum determination conditions of reducing sugar using DNS colorimetry were DNS a- mount： 4. 0 mL, coloration time： 5.0 rain, reaction temperature： 87.0 ~C. The actual concentra- tion of reducing sugar was obtained to be 94. 66 mg/L, which was consistent with the theory predicts under the optimal conditions. According to the optimum determination conditions, the precision, re- peatability and accuracy of the method were verified using apple, peach, grape, hami melon, navel orange and pineapple as representative fruits. The standard deviations, relative standard deviations and recoveries of the reducing sugar contents in the 6 fruit species were in the range of 0. 1% - 0.5% , 2.0% - 4. 8% , 90. 6% - 104.2% , respectively. The study provided a reliable method for accurate, efficient and cost-effective detection of reducing sugar contents in fruits.