Optimized Extraction Method of Acetic Acid in Vinegar and Its Effect on SNIF-NMR Analysis to Control the Authenticity of Vinegar

作者：Ko Wen Ching; Cheng Ju Yun; Chen Po Yen; Hsieh Chang Wei^*

来源：Food and Bioprocess Technology, 2013, 6(8): 2202-2206.

DOI：10.1007/s11947-011-0766-5

• Extractive distillation
• H-2-NMR
• SNIF-NMR

Site-specific natural isotope fractionation by nuclear magnetic resonance (SNIF-NMR) is an accurate method for examining food adulteration. SNIF-NMR can be used to determine the ratio of deuterium to hydrogen (D/H) of a specific molecule position. Because the quantity of D differs between synthetic and fermented acetic acids, the method can be used to accurately monitor food adulteration. However, the effect of pretreated food on the results of SNIF-NMR has rarely been discussed. We present an extractive distillation method to increase the purity of acetic acid for fractionation; we used an orthogonal array experimental design to determine the optimal extraction conditions. We discuss the influence of extract solvents and sample concentration on the (D/H)(CH3) values calculated from the NMR results. The optimal conditions for extracting acetic acid were found to be a sample-to-solvent ratio of 1:1, seven extractions, and an extraction time of 15 min. The extraction rates for acetic acid were 93.65% and 80.57% when ethyl acetate and diethyl ether, respectively, were used. The acetic acid concentration of the ethyl acetate- and diethyl ether-extracted samples was further improved by distillation from 5 g/100 mL to 33.84 and 51.65 g/100 mL, respectively.

• 出版日期2013-8