Non-enzymatic browning in peach puree during heating

Non-enzymatic browning in peach puree (11 degrees Brix) due to extended the rmal treatment was investigated. Absorbance at 420 nm, colorimetric paramet ers (CIE L*, a*, b* and Delta E*), content in sugars (fructose, glucose and sucrose) and hydroxymethylfurfural were used to estimate the extent of non enzymatic browning during heating at high temperatures (80, 85, 90, 95 and 98 degrees C) for 480 min. Zero and first order kinetics were applied to de scribe evolution of relative absorbance at 420 nm. Relative luminosity and sucrose content follow a first order kinetic. Colour difference was success fully adjusted to a model including two stages: the first one includes the colour formation and it follows a kinetic of order zero and the second incl udes the colour destruction and it follows a first order kinetic model. Bot h first and autocatalytical models can describe HMF formation. Parameter b* was significantly reduced with heating time, especially at higher temperat ures, on the contrary parameter a* increases during heating. The Arrhenius model described well the temperature dependence of the reaction rate consta nt for all the parameters considered. (C) 1999 Canadian Institute of Food S cience and Technology. Published by Elsevier Science Ltd. All rights reserv ed.