Development of a new fluorometric method for the determination of hydroxymethylfurfural in some food samples

5-Hydroxymethylfurfural (5-HMF) is a heterocyclic compound released as a result of the breakdown of sugar through the Maillard reaction when carbohydrate-rich foods are subjected to a heat treatment. The 5-HMF content of many different food samples (honey, molasses, jam, coffee, beer, apple juice, etc.) can vary greatly. In these food samples, 5-HMF is usually found by reducing sugars at room temperature, and its amount may increase with improper storage and/or heat treatment. Therefore, 5-HMF is considered an indicator of quality deterioration caused by uncontrolled heating or improper storage conditions in these carbohydrate-containing foods. On the other hand, 5-HMF has been shown to have cytotoxic, mutagenic, and also carcinogenic effects in some studies. Therefore, there is a great need to develop a simple, sensitive, selective and economical method for continuous monitoring and determination of 5-HMF levels in foods. The resorcinol compound in the original spectrophotometric Saliwanoff test was used as a fluorometric HMF probe for the first time in the literature with this thesis. As a result of the incubation of the resorcinol probe with 5-HMF, the initial fluorescence intensity of the probe decreases due to the formation of the condensation product (λem = 302 nm), because although the resorcinol probe fluorescence, the condensation products are not fluorescent. Chemical characterization of the compound was carried out by FT-IR and MS techniques. In the developed fluorometric-based method, a decrease in the initial fluorescence intensity (ΔI) of the probe was realized with the increase of 5-HMF due to the reaction between the detector molecule and 5-HMF, and the calibration graph of the relevant compound was created based on the amount of decrease in the intensity of the probe (r2 0.9994). The detection limit (LOD) was found to be 2.8 μM by fluorometric method with high selectivity with resorcinol probe. Due to its advantages such as speed, high selectivity and sensitivity for 5-HMF detection, this proposed approach has been successfully applied in the determination of 5-HMF in some honey, jam and molasses (pekmez) samples. The results obtained by the fluorometric method were compared with the HPLC method chosen as the reference method and there is a good correlation between the findings of both methods.