Decomposition of Hydroxymethylfurfural in Solution and Protective Effect of Fructose

Time-course changes were studied on both concentration and spectral curve shape of 5-(hydroxymethyl)furfural (HMF) in solution. A significant and progressive absorbance drop at 284 nm was observed as well as the concomitant appearance of a new band at 252 nm with standard HMF solutions and glucose, saccharose, maltose, and lactose solutions. These changes depended mainly upon HMF starting concentration and were affected by both the storage temperature and the time between the preparation of the solution and the spectrophotometric measurement. There were less significant changes in honey, high-fructose corn syrup, and fructose solutions. The results indicate that fructose has a protective effect on HMF decomposition in solution. The spectrophotometric measurement should be made within 6 h after sample preparation, and the solutions should be kept at 4−8 °C to avoid HMF decomposition. Honey solutions with high HMF starting concentration showed significantly lower concentrations when they were clarified by ultrafiltration, compared with the usual clarification with Carrez reagent. This last fact could be attributed to a deficient sample deproteinization, which is improved either by ultrafiltration or by using a larger amount of Carrez reagent. Keywords: Hydroxymethylfurfural; honey; syrup; fructose; glucose; sugars; food