AIST Stories No2

28From AIST to the Innovative World001020304050607020406080100SweetnessTemperature (°C)120140160GlucoseSucroseFructoseNatural sweetener manufacturing technology winning over the worldRealizing the sweetness of fructose from potatoes and cornMaking a natural sweetener from low-cost sweet potatoToday one might have a sense of it being somewhat behind the times but in the past, sweetness conveyed the impression of wealth. Japan up until around the 1960s relied on imports for the majority of its sugar, which was high priced. Sweet things were thus considered luxuries. In contrast, during the post-war era Japan faced a food shortage and efforts were focused on the cultivation of sweet potatoes. On this account, a large surplus of sweet potato resulted. Well then, couldn’t one reduce imports of costly sugar by producing natural sweetener from sweet potato that could be harvested in mass quantities? In 1962, research and development of natural sweeteners commenced in Japan, with the research institutes of the various government ministries and agencies competing to be the first to succeed.There are in fact various sugars that can be used as natural sweeteners. The main ingredient of table sugar is sucrose, whereas the main component of the Japanese sweetener mizuame is maltose. Further, there is fructose, which is found in fruits and honey, and glucose that is used in intravenous solutions in hospitals. By the 1960s, technology for extracting glucose from sweet potato starch had already been developed. The problem was that glucose is only 60–70% as sweet as table sugar. In contrast, fructose is the sweetest of all natural sugars and at low temperatures in particular, its sweetness is 1.7-times that of table sugar. How could the glucose contained in sweet potato, which could be produced cheaply and in large quantities, be transformed into highly sweet fructose? This was the challenge taken up by Dr. Yoshiyuki Takasaki and his group at AIST (at the time known as the Fermentation The original natural sweetener sugar is made from sugar cane and sugar beets. However, areas that can cultivate these crops are limited and sugar prices tend to be high. Can’t a sweetener like sugar be made from a crop that can be grown cheaply in great quantities? In 1965, AIST solved this challenge by using a technology to convert glucose into fructose by using glucose isomerase. This patent was exported overseas and as the pioneer of natural sweetener manufacturing technology, a low-cost and safe sweetener was supplied to the world.Sugar typeMolecular formulaSweetnessSucrose (sugar)C12H22O11100GlucoseC6H12O660~75FructoseC6H12O6115~175LactoseC12H22O1115~30MaltoseC12H22O1130~45InvertoseSweeter than sugarHoneySweeter than sugarSweetness of various sugarsSugar sweetness and temperature▲‌‌Fructose sweetness is significantly impacted by temperature; its sweetness is 1.5-times that of sucrose at approximately 5°C and roughly equivalent at around 40°C.*Sucrose‌set‌at‌100AIST’s first patent export dramatically changed the food industryAnother success at AIST!