What is Allulose? A Complete Guide to D-Psicose

What is Allulose?

Allulose, also known as D-psicose or D-allulose, is a rare monosaccharide sugar with the chemical formula C₆H₁₂O₆ — the same as glucose and fructose. It is classified as a C-3 epimer of D-fructose, meaning it differs from fructose only in the configuration of the hydroxyl group at the third carbon atom.

Despite being a "sugar" in chemical terms, allulose behaves very differently from conventional sugars in the human body. It provides approximately 0.4 kcal/g (about 1/10 the calories of sucrose) and has a near-zero glycemic index.

Chemical Classification

Allulose belongs to the rare sugar family — monosaccharides that exist in extremely small quantities in nature. Unlike abundant sugars such as glucose (in starch) or fructose (in fruit), rare sugars like allulose are found only in trace amounts.

As a ketohexose (6-carbon ketose sugar), allulose shares the same molecular weight as glucose (180.16 g/mol) but has distinctly different biological properties due to its unique stereochemistry.

History of Discovery

• 1940s: Allulose was first isolated from wheat bran by researchers studying rare sugars
• 1994: Professor Ken Izumori at Kagawa University (Japan) discovered the enzymatic pathway for converting fructose to allulose, later known as the Izumori Ring
• 2011: The enzyme D-tagatose 3-epimerase (DTEase) enabled industrial-scale bioconversion of fructose to allulose
• 2014: FDA accepted allulose as Generally Recognized as Safe (GRAS) in the United States
• 2019: FDA ruled that allulose does not need to be counted as "added sugar" on Nutrition Facts labels
• 2020s: Major food companies worldwide began incorporating allulose into commercial products

Natural Sources

Allulose occurs naturally in small quantities in several foods:

Due to its extremely low natural abundance, commercial allulose is produced via enzymatic conversion from fructose (typically derived from corn starch).

Commercial Production

Modern allulose production uses the enzymatic epimerization process:

1. Feedstock preparation: Fructose solution derived from corn starch
2. Enzymatic conversion: D-tagatose 3-epimerase (DTEase) or D-psicose 3-epimerase (DPEase) converts fructose → allulose
3. Separation and purification: Chromatographic separation, filtration, crystallization
4. Drying and packaging: Final product as crystalline powder

Baolingbao Biology operates one of the world's largest allulose production lines with an annual capacity exceeding 10,000 metric tons.

Comparison with Other Sweeteners

Allulose is unique among low-calorie sweeteners in that it participates in Maillard browning reactions — enabling proper browning in baked goods, something that erythritol, stevia, and monk fruit cannot achieve.