Although traces of 1,5-anhydroglucitol (AG), or 1-deoxyglucose, can be ubiquitously found in natural world, we have previously purified bulk AG with a high yield (5 g/100 g) from Polygalae radix, which has been used as a traditional Chinese herbal medicine. We have obtained the following findings. Sweetness of AG is 58% of that of sucrose (100%). It is chemically stable under acidic or alkaline pH. About 60% of dose of AG to rats is excreted into urine within 9 h, suggesting AG is metabolically stable. AG prevents, in a dose-dependent manner, the increase in blood glucose levels following glucose ingestion in rats, suggesting glucose absorption competes with AG at intestinal absorption site. In this study, we describe the production and properties of the two functional sugars derived from AG. Indeed, AG can be converted to 1,5-anhydrofructose (AF) and 1,5-anhydro-3-keto-fructose (AKF) by pyranose oxidase at 37C at pH 4-5 during 24 h and at neutral pH during 72 h, respectively. It is known that AF is produced from glycogen or starch by alpha 1,4-glucan lyase and then promptly metabolized to AG by NADPH-dependent AF reductase in animal and higher plant tissues. AF has been well known to have multifunctional properties including strong anti-oxidative, anti-browning, ant-fungal, anti-tumor, and anti-obesity activities. No reports about AKF properties have so far been shown, but we found that AKF (0.1-1%), but not AF, inhibited browning of apple juice in a dose-dependent manner. Maillard reaction activity of 1% AKF with 1% glycine at pH 7 and at 100℃ for 5 min was higher than those of AF and other reducing sugars. Further studies on characterization of AKF are needed. In conclusion, AG is a promising functional sweetener and could be used as a source of the multifunctional sugar AF or AKF.

Professor Yotaro Konishi received his PhD in Health Science from Tokushima University School of Medicine, Japan, in 1979. Since 1981, he worked at the Faculty of Food Science and Nutrition, Osaka City University (OCU), Japan, and went to Louvain Catholic University, Belgium and studied there as visitor (1985-86). He served as Professor (2004-15) and Dean (2008-10) at OCU. After retirement from OCU, he is now Professor at Faculty of Health Science, Kio University, Japan. He also served on a director of Japan Society of Nutrition and Food Science (2010-13, 2016-17). He is an active researcher in food science and nutrition for the past 40 years. He has in depth research works on underexploited and useful food resources such as amaranth and quinoa grains. Recently he has been working on research and development of 1,5-anhydroglucitol, a functional rare sugar, and invited as a keynote speaker from the 3rd International Symposium on Processing of Foods, Vegetables and Fruits, which was held in Malaysia 2014.