Quantitative Determination of Thiamine-Derived Taste Enhancers in Aqueous Model Systems, Natural Deep Eutectic Solvents, and Thermally Processed Foods

To obtain high-kokumi-active building blocks, which can be used to produce savory process flavors, it is essential to obtain a better understanding on the formation rate of kokumi-active compounds, such as 3-(((4-amino-2-methylpyrimidin-5-yl)methyl)thio)-5-hydroxypentan-2-one or 2-methyl-5-(((2-methylfuran-3-yl)thio)methyl)pyrimidin-4-amine. The present work showed quantitative studies in several model reaction systems on the recently discovered kokumi-active thiamine derivates. It was possible to show that the thiamine conversion in aqueous model reactions could be directed toward the taste-modulating compounds by adjusting the pH value (6.5), the heating time (120 min), and the heating temperature (120 °C). With the development of a new natural deep eutectic solvents (NADES) system consisting of thiamine, cysteine, ribose, and sodium hydroxide, it was possible to obtain high yields of the targeted taste-modulating analytes, such as 3-(((4-amino-2-methylpyrimidin-5-yl)methyl)thio)-5-hydroxypentan-2-one and 2-methyl-5-(((2-methylfuran-3-yl)thio)methyl)pyrimidin-4-amine. Furthermore, the current study showed that kokumi-active thiamine derivates, such as S-((4-amino-2-methylpyrimidin-5-yl)methyl)-l-cysteine, 3-(((4-amino-2-methylpyrimidin-5-yl)methyl)thio)-5-hydroxypentan-2-one, 2-methyl-5-(((2-methylfuran-3-yl)thio)methyl)pyrimidin-4-amine, and 5-(((furan-2-ylmethyl)thio)methyl)-2-methylpyrimidin-4-amine, can be classified as natural "food-borne"taste enhancers and occur in thiamine-rich, thermally treated foodstuff.