Fructose is a naturally-occurring monosaccharide (simple sugar) also known as “fruit sugar.” It is the sweetest of all the naturally-occurring carbohydrates, and it is the sugar most easily dissolved in water. Fructose is the principal component of most honey and is responsible for keeping honey from crystallizing.
Fructose can bind with another simple sugar, glucose, to form sucrose—the substance we call table sugar. Most sweet foods contain varying amounts of fructose, glucose, and sucrose but a few—including honey, apples, and pears—are generally extra high in fructose. There are, however, certain types of honey have more glucose than fructose, a situation that causes crystallization.
Natural fructose should not be confused with high-fructose corn syrup, which is product manufactured by treating corn syrup with specific enzymes that convert some of the glucose to fructose. Both natural fructose and high-fructose corn syrup produce hydroxymethylfurfural when heated.