Fructose is the sweetest natural sugar, and it hits the tongue first
Gram for gram, fructose tastes roughly 1.2 to 1.8 times as sweet as table sugar, making it the sweetest carbohydrate found in nature. Its sweetness arrives sooner, peaks higher and fades faster than sucrose. And contrary to popular belief, the rise of corn syrup barely changed how much fructose Americans eat relative to glucose.
Fructose, or fruit sugar, is one of three simple sugars in the human diet, alongside glucose and galactose. It occurs in honey, fruit, flowers, berries and most root vegetables, often bonded to glucose as sucrose. French chemist Augustin-Pierre Dubrunfaut discovered it in 1847, and the English chemist William Allen Miller coined the name in 1857 from the Latin for fruit. Its older name, levulose, reflects the way its solutions rotate polarised light to the left, just as dextrose turns it to the right.
It is also the most water-soluble sugar, which makes it hard to crystallise and keeps fructose-rich candies soft. It grabs moisture quickly and releases it slowly, so baked goods stay moist longer. Because more of it sits in an open-chain form than glucose, it browns faster in the Maillard reaction, which can overbrown a cake. When mixed with sucrose, aspartame or saccharin, the blend tastes sweeter than the parts would predict. Researchers have long proposed turning fructose into a liquid fuel, dimethylfuran, though the route has not been put into practice.
Industry makes it from starch, sucrose and inulin, the last from roots such as chicory. Corn starch is broken into glucose, and an enzyme converts part of that into fructose to make high-fructose corn syrup; HFCS-55 goes mainly into soft drinks. Since table sugar splits into equal parts glucose and fructose, and common syrups have roughly equal ratios too, the switch from cane and beet sugar did not dramatically alter the overall balance.
Fruits vary. In apples and pears, free fructose outweighs free glucose by better than two to one, whereas apricots tilt the other way, with under half as much fructose. That matters for young children, whose intestines absorb fructose less readily than glucose; unabsorbed fructose draws water into the gut, and apple and pear juices can cause diarrhoea. After absorption, fructose travels through the portal vein to the liver.
Source: Fructose
