Agriculture and Forestry
Turkish Journal of Agriculture and ForestryKinetics of Nonenzymatic Browning Reaction in Citrus Juice Concentrates during Storage
Ankara University, Faculty of Agriculture, Department of Food Engineering, Dışkapı 06110 Ankara - TURKEY
Abstract: The kinetics of nonenzymatic browning in citrus juice concentrates (orange, lemon, grapefruit and tangerine) during 8 weeks of storage at 28, 37 and 45 ºC were investigated. Browning development was followed by measuring absorbance at 420 nm (A420) and using CIE-Lab color system. Analysis of kinetic data from A420 values suggested a zero-order reaction for nonenzymatic browning, while changes in L* and b* parameters followed a first-order reaction. Activation energy for nonenzymatic browning determined by A420 values ranged from 17.60 to 35.27 kcal mol-1, while those for L* and b* parameters were 6.67-28.99 kcal mol-1 and 15.38-34.2 kcal mol-1, respectively. Activation energies were higher in orange (28.99-35.27 kcal mol-1) and tangerine (27.84-33.1 kcal mol-1) juice concentrates than those in grapefruit (6.74-27.81 kcal mol-1) and lemon (6.67-17.6 kcal mol-1) juice concentrates. The lower activation energies determined for grapefruit and lemon juice concentrates indicated that nonenzymatic browning reactions are favored in these samples.
Key Words: Citrus juice concentrate, nonenzymatic browning, color, storage, kinetic
Turk. J. Agric. For., 27, (2003), 353-360.
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Other articles published in the same issue: Turk. J. Agric. For.,vol.27,iss.6.