|Molar mass||180.16 g·mol−1|
|Melting point||58 °C (136 °F; 331 K) |
Except where noted otherwise, data is given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
|what is: / ?)(|
D-Psicose (D-allulose, D-ribo-2-hexulose, C6H12O6) is a low-energy monosaccharide sugar present in small quantities in natural products. First identified in wheat more than 70 years ago, psicose is a C-3 epimer of D-fructose, and is present in small quantities in agricultural products and commercially prepared carbohydrate complexes. The sweetness of psicose is 70% of the sweetness of sucrose.
Though the U.S. Food and Drug Administration (FDA) allows psicose to be used as a food ingredient, psicose is not permitted in the European Union. In February 2015, London-based Tate & Lyle released its proprietary variant of psicose, known as Dolcia Prima allulose. The company plans to market it for use in foods and beverages as a low-calorie sugar substitute in beverages, yogurt, ice cream, and baked products.
Two studies into the toxicity of psicose found that rats fed diets with extremely high levels of D-psicose appeared to suffer harm to the intestinal tract. The studies also found that the relative weights of liver and kidney were significantly higher in the D-psicose group than in the sucrose group. The studies' authors noted, "the effects of long-term feeding of D-psicose must be elucidated prior to utilization as a physiologically functional food." U.S. nutritionist Kantha Shelke seconded these concerns, and warned that "the food marketplace is being used as a test laboratory for this product."
A study sponsored by psicose producer Tate & Lyle showed that because psicose is not generally metabolized, its caloric value is significantly lower than table sugar - nearly zero. The company maintains that psicose can benefit consumers who monitor their sugar intake because it does not impact the glycemic response significantly. A study cited by Tate & Lyle showed that when 25 g of psicose were ingested compared to 25 g of sucrose, psicose did not raise blood sugar levels above the baseline for two hours after ingestion.
The first mass-production method for psicose was established when Ken Izumori at Kagawa University in Japan discovered the key enzyme, D-tagatose 3-epimerase, to convert fructose to D-psicose in 1994. This method of production has a high yield, but suffers from a very high production cost.
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