Psicose contents in various food products and its origin

To elucidate the history of human exposure of psicose, a determination method of psicose (D/L-psicose) in various food products has been developed: post column high-performance liquid chromatography (HPLC) using gel permeation column in ligand exchange mode coupled with pulsed amperometric detection (PAD). The calibration curve of D-psicose was linear in a concentration range of 5 to 150 mu g/ml with a correlation coefficient of 0.9999. With ultrasonic extraction and C18 Sep-pack filtration methods, the samples for HPLC analysis could be prepared from various food products within 0.5-1.5 h without any interference materials. The psicose recovery (n = 5) from coffee and corn-snack was found to be 96.6% with relative standard deviation (R.S.D.) of 1.9% and 96.7% with R.S.D. of 3.0%, respectively. The resultant psicose content varied from 0.5mg/100g (coffee) to 130.6mg/100g (Worcester sauce). In particular, confectionery products and seasoning sauces exhibited higher psicose content than other studied products. In high sugar food products, heat processing had a marked effect on the production of psicose. The psicose formation due to heating was suggested to be a non-enzymatic reaction.