榨菜腌制过程中有机酸变化

Variations in Organic Acids in Mustard during Pickling

以青菜头、各腌制时期盐菜块以及榨菜腌制水为研究对象,采用反相高效液相色谱法对其有机酸的变化进行分析和研究。色谱柱:Agilent TC-C18(4.6mm×250mm,5μm),色谱条件:将体积分数3%甲醇-0.5%KH2PO4,并用H3PO4调制pH2.8的溶液作为流动相,流速0.8mL/min;检测波长215nm;柱温17℃。结果表明:8种有机酸能有效地分离,回收率均在95.73%～100.55%,相对标准偏差2.04%～3.12%,呈现出良好的线性相关性和较高的准确度。水浴、醇提法、超声波3种不同提取方法中,超声波提取法提取榨菜中有机酸的效果最好。在各腌制过程中榨菜以及榨菜腌制水中总有机酸的增长为一次腌制>二次腌制>三次腌制,其中乳酸含量最高,一次腌制及二次腌制过程中乳酸占总有机酸29.94%和38.55%,3次腌制后期乳酸占总有机酸73.50%;在所有的加工榨菜的工序中,淘洗过程对有机酸的影响最大,人工调配工序其次。

In this study, raw mustard and pickled mustards at different pickling stages as well as pickle juice were analyzed by RP-HPLC for their variations in organic acid contents. In the RP-HPLC analysis, the chromatographic column used was an Agilent TC type C18 column. The separation of organic acids was performed by using a mobile phase made up of 3% methanol and 0.5% KHEPO4 which adjusted to pH 2.8 with H3PO4 at a flow rate of 0.8 mL/min. The detection wavelength was set as 215 nm, and the column temperature was controlled at 17 ℃. Eight organic acids were separated effectively under these conditions. The organic acids exhibited a recovery rate varying between 95.73% and 100.55% and a relative standard deviation ranging from 2.04% to 3.12%. The RP-HPLC method had a good linear correlation and was accurate. Sonication was found to be better for extraction of organic acids than water bath heating and ethanol extraction. The contents of organic acids in pickled mustards and pickle juice increased as the pickling number increased from 1 to 3. The most predominant acid was lactic acid, which accounted for 29.94% and 38.55% of total organic acids in once pickled and twice pickled samples, respectively. The relative content of lactic acid was 73.50% during the late part of the third pickling cycle. Among all processing stages of mustard, rinsing had the largest impact on organic acids followed by manual acidity adjustment.