糠氨酸标准溶液的储存稳定性以及盐酸浓度对牛奶中糠氨酸检测结果的影响

本试验旨在研究糠氨酸标准溶液的储存稳定性以及牛奶前处理过程中盐酸浓度对糠氨酸检测结果的影响。试验1:分别用3.0、1.0和0.1 mol/L盐酸配制不同浓度糠氨酸标准溶液(1和5 mg/L),并分别放置于-20、4℃和室温(25℃)下,于第1、3、5、8、10、12、14、15、17和21天采用超高效液相色谱法测定糠氨酸含量(每个处理设3个平行),分析糠氨酸标准溶液在不同储存条件下的稳定性。试验2:设置11种不同浓度的盐酸,水解牛奶后测定糠氨酸含量,每个浓度设4个平行,试验独立重复3次,分析盐酸浓度对牛奶中糠氨酸检测结果的影响以及结果的重复性。结果表明:1)0.1和1.0 mol/L盐酸配制的糠氨酸标准溶液不稳定,3.0 mol/L盐酸配制的糠氨酸标准溶液稳定性较好,可于-20、4℃和室温条件下保存21 d。2)盐酸浓度显著影响牛奶水解效果(P<0.05),当水解液中盐酸浓度达到9.17 mol/L时糠氨酸可以完全游离出来,检测结果重复性比较好。因此,建议用3.0 mol/L盐酸配制糠氨酸标准溶液,于4℃保存,21 d内使用;水解牛奶所用盐酸浓度应使牛奶水解液中盐酸浓度至少达到9.17 mol/L。

Storage Stability of Furosine Standard Solution and Effects of Hydrochloric Acid Concentration Used for Milk Hydrolysis Procedure on Furosine Detection Result

This experiment was to investigate the storage stability of furosine and the effects of hydrochloric acid(HCl)concentration used for milk hydrolysis procedure on furosine detection result.In experiment 1,in order to investigate the stability of furosine standard solution under different storage conditions,different concentrations of furosine standard solutions(1 and 5 mg/L)were prepared with different HCl solutions(3.0,1.0 and 0.1 mol/L),and kept at different temperatures-20,4℃and indoor temperature(25℃)]for different time(1,3,5,8,10,12,12,15,17 and 21 days,n=3 for each treatment),and then determined the furosine content using ultra performance liquid chromatography(UPLC)method.In experiment 2,in order to investigate the effects of HCl concentration used for milk hydrolysis procedure on furosine detection result and the repeatability of detection result,eleven different concentrations of HCl were used to hydrolyze the milk for furosine content determination.Four samples were used in each concentration,and three independent experiments were conducted separately.The results showed as follows:1)furosine standard solutions prepared with 0.1 and 1.0 mol/L HCl degraded easily,but the furosine standard solutions prepared with 3.0 mol/L HCl exhibited good stability when they were stored at-20,4℃or room temperature(25℃)within 21 days.2)HCl concentration significantly affected the hydrolysis effect of milk(P<0.05),and the milk could be completed hydrolyzed to release the furosine in milk and presented good repeatability when the concentration of HCl in the hydrolysate was up to 9.17 mol/L.Therefore,it is suggests that furosine standard solution should be prepared with 3 mol/L HCl and stored at 4℃within 21 days.In addition,the concentration of HCl used in milk hydrolysis procedure should be such that can make the concentration of HCl in the hydrolysate reaches at least 9.17 mol/L.