挂面中丙二醛含量测定方法的研究

丙二醛含量是评价挂面酸败的重要指标之一,研究了三氯乙酸抽提法(TCAEM)和直接反应法(DRM)测定挂面中丙二醛含量的试验条件,并比较了两种方法的加标回收率、精密度、检测限和重复性。结果显示,TCAEM的较佳试验条件为三氯乙酸质量分数10%、料液比1∶12、搅拌时间2 h;DRM的较佳试验条件为醋酸缓冲液pH 2.5、SDS质量分数4%、正丁醇和吡啶的混合溶剂溶剂比6∶1。向样品中分别添加10、20、30μg/mL 3个浓度水平的丙二醛标准物(TEP)时,三氯乙酸抽提法平均回收率分别为82.61%、83.33%、82.15%,变异系数(RSD)为1.016 0%,最低检测限为12.50μg/kg(K=2.13),重复性试验RSD为1.25%(n=6);直接反应法平均回收率分别为79.78%、79.60%、80.97%,RSD为1.776 3%,最低检测限为39.08μg/kg(K=2.171),重复性试验RSD为1.75%(n=6)。试验结果表明TCAEM更适于挂面中丙二醛含量的测定。

Study of Malondialdehyde determination methods in dry noodles

The content of malondialdehyde(MDA) is one of important indexes to evaluate rancidity of dry noodle.The experimental conditions of trichloroacetic acid extraction method(TCAEM) and direct response method(DRM) were optimized to determine the content of MDA in dry noodle in the paper,and recoveries,precision,detection limit and repeatability of these two methods were compared.The results showed that optimal extraction conditions of TCAEM were that,TCA mass fraction 10%,ratio of solid to liquid 1∶12,stirring time 2 h;optimal extraction conditions of DRM were that acetic acid buffer solution pH2.5,SDS mass fraction 4%,the mixture of N-butyl alcohol and pyridine 6:1(v/v).When the samples were spiked with 10,20 and 30 μg/mL of MDA standard materials(TEP),the average recoveries were 82.61%、83.33% and 82.15% respectively by TCAEM,while the relative standard deviation(RSD) was 1.016 0% with the lowest detection limit of 12.50 μg/kg(K=2.13) and repeatability experiment RSD1.25%(n=6).The average recoveries were 79.78%,79.60%and 80.97% respectively by DRM and RSD was 1.776 3% with the lowest detection limit of 39.08 μg/kg(K=2.171) and repeatability experiment RSD 1.75%(n=6).Test results showed that TCAEM was more suitable for the determination of MDA content in dry noodle.