High Sensitivity Analysis and Food Processing Stability of Rare Sugars

To evaluate the stability of rare sugars, i.e., sorbose, allose, tagatose and allulose, in food products containing rare sugar syrup (RSS) during cooking, we developed a highly sensitive analysis method using high performance liquid chromatography (HPLC) with corona charged aerosol detector (CAD) and analyzed the rare sugars in a Maillard reaction mixture and in food products available at market. In the Maillard reaction, the amounts of each rare sugar decreased at the initial pH of 6.0. Further, the increase in allulose was accelerated in reaction mixtures at pH 7.5. The stability of rare sugars, which are added to improve food functions during food processing, was greatly influenced by the pH, temperature and heating time. Surprisingly, allulose was retained at the highest level (86.0 %-88.5 %) under the various cooking conditions, while the other rare sugars were obviously decreased. Therefore, it was suggested that allulose can be maintained under various manufacturing conditions, including under weakly alkaline treatment.