Formaldehyde (FA) production in water-soluble fish extracts containing maltodextrins depends on the specific diffusion and freeze-concentration of reactants in the unfrozen water (UFW) phase. A WLF model did not describe the kinetics of FA production when reaction rate was used as the output variable. Methodological limitations in determining Tg and Cg restricted the use of this equation. The kinetics of FA production were alternatively defined by an exponential model, which, however, would not apply near the freezing point as it does not consider the inflection due to dilution of reactants. Limitations in determining the freeze-concentration of reactants in the UFW phase also prevented the study of whether FA production followed Arrhenius kinetics. However, the use of reaction rate constants for the hydrolysis of nitrophenyl taking place under diffusion-limiting conditions [data from Champion, D., Blond, G., & Simatos, D. (1997) Reaction rates at subzero, temperatures in frozen sucrose solutions: a diffusion-controlled reaction. Cryo-Letters, 18, 251–260] showed that it apparently followed an Arrhenius behavior in the frozen state

Xunta de Galicia is thanked for financial support to Dr Herrera in the University of Helsinki, Department of Food Technology. This work was carried out with funds of the European Commission Contract ERBFAIRCT96-1085 ‘Enhancement of Quality of Food and Related Systems by Control of Molecular Mobility’

9 páginas, 7 figuras, 2 tablas

Peer reviewed