Pressure-Thermal Kinetics of Furan Formation in Selected Fruit and Vegetable Juices

Furan, a potential carcinogenic compound, can be formed in array of processed foods. The objective of this study was to conduct kinetic studies in pineapple juice and assess the interactive effects of pressure (0.1 to 600 MPa) and temperature (30 to 120 degrees C) on furan formation. Additional experiments were carried out in tomato, watermelon, cantaloupe, kale, and carrot juice to understand the influence of matrix and juice pH. Furan was monitored in raw (control) and processed samples by automated headspace gas chromatography mass spectrometry, and quantified by calibration curve method with d(4)-furan as internal standard. The data were modeled using zero-, first-, and second-order equations. The zero-order rate constants (k(T,P) ), activation energy (E-alpha ), and Gibbs free energy of activation (Delta G(double dagger)) of furan formation in thermally processed (TP; 90-120 degrees C) pineapple juice were found to be 0.036-0.55 mu g/kg/min, 98-114 kJ/mol, and 173.9-180.5 kJ/mol, respectively. Furan concentration was negligible and close to the detection limit (0.37 mu g/kg) after pressure treatment (600 MPa at 30 degrees C) of juice samples. For similar process temperatures, the rate constants of pressure-assisted thermally processed (PATP; 600 MPa at 105 degrees C) pineapple juice were lower than that of TP samples. Furan formation was influenced by juice matrix and pH. On the other hand, PATP markedly suppressed furan (0.7 to 1.6 mu g/kg) in these selected juices. In conclusion, furan formation increased with process temperature and treatment time, while pressure treatment at ambient temperature did not promote its production. Furan formation in TP fruit juices was also influenced by juice matrix and pH, but these were not the significant factors for PATP-treated juices.