Study on 5-hydroxymethylfurfural formation in milk during UHT treatment measured by two analytical procedures
1996
Morales, F.J. | Romero, C. | Jimenez-Perez, S. (Instituto del Frio CSIC, Madrid (Spain). Unidad de Productos Lacteos)
Whole milk was heated by UHT-direct treatment in an APV pilot plant. Sterilization temperatures between 135 and 150 degrees for holding times from 2.5 to 20 s were used. Moreover, effects of recycling (0; 2.5; 5 and 10 percent) were taken into account. HMF was measured by the traditional colorimetric procedure as well as by reversed-phase HPLC. Ranges from 0.75 to 11.27 micromol/l and 0.69 to 7.43 micromol/l were measured by calorimetric and RP-HPLC, respectively. In all samples studied, higher HMF values were detected by the calorimetric procedure. The difference between the two methods was higher in samples with a more severe heat treatment. The calorimetric procedure could give an overestimation of HMF content due to the presence of other highly reactive carbonyl compounds that can react with the calorimetric reagent. HMF behaviour during UHT treatment was best described by zero-order kinetics. Apparent energies of activation of 124 +- 10 kJ/mol and 117 +- 1 kJ/mol were calculated for the calorimetric and RP-HPLC method, respectively. The presence of HMF in heated and raw milk was compared using both methods. In raw milk, 71.6 percent (67.1-77.0) of total HMF content measured by the calorimetric procedure was due to interferences in the method
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