On the Determination of Benzoic Acid in Imported Korean Ginseng Tea and Dried Chinese Bamboo Shoot in Relation to the Pursuit of its Origin

Abstract

Four extraction-cleanup procedures, i. e., liquid-liquid extraction using ether (Method A), steam distillation (Method B), modified steam distillation (Method C) and alkaline hydrolysis (Method D), were tested for the gas-liquid chromatographic determination of benzoic acid in Korean ginseng tea and dried Chinese bamboo shoots. The lowest values were obtained by Method A. Those obtained by Method B were a little higher while the results with Method C increased with increase in the volume of the distillate. The highest values were obtained by Method D, the results being 5.1-32.6 times larger than those obtained by Method A. It is presumed that only free benzoic acid is extracted by Method A, while both free benzoic acid and combined benzoate could be extracted by Method D. The results of Methods B and C indicate that a part of the combined benzoate was decomposed into free benzoic acid during steam distillation. Since artificially added benzoic acid as well as its sodium salt would be present in the free form in these foods while most of the naturally occurring benzoates would be in combined form, it is recommended to apply both Methods A and D for the differentiation of artificially added benzoic acid and benzoate from naturally occurring food ingredients. Combined benzoate was provisionally calculated by subtracting the value obtained by Method A from that obtained by Method D. The absence of free benzoic acid or benzoate in food shows that these substances have not been artificially added. Steam distillation methods seem to be inappropriate, as mentioned above.