Abstract
Dietary glycosylceramide has several benefits including reducing transepidermal water loss and improving intestinal microbial flora. We have elucidated that koji, the base for Japanese traditional cuisines, contains abundant glycosylceramide. To investigate the content of koji glycosylceramide contained in Japanese foods made with koji, a quantitative method of koji glycosylceramide using TLC-orcinol sulphate staining was investigated. First, the existence of ions having m/z of 4,8-sphingadienine and 9-methyl-4,8-sphingadienine, major molecules comprising koji glycosylceramide, was confirmed by ESI-MS. Using an OPA derivatization-HPLC method, the validity of a TLC-orcinol sulphate staining method as a glyocsylceramide-quantitative method was verified. Using a TLC-orcinol sulphate staining method, it was elucidated that unfiltered sake, amazake, and salted koji contained abundant amounts of koji glygosylceramide of up to 4.15 mg glycosylceramide per serving. From the information elucidated in this study, it was estimated that a Japanese meal containing koji-based foods could contain 8.69 mg of glycosylceramide. This is the first study to elucidate the content of glycosylceramide contained in Japanese foods made with koji.
