Impact of Starch Gelatinization on the Kinetics of Maillard Reaction in Freeze-Dried Potato Systems

The objective of the present work was to contribute to the understanding of the changes in water-distribution and water–solids interactions that take place after starch gelatinization and to elucidate their influence on the kinetics of Maillard reaction in low-moisture potato starch systems. Maillard reaction was studied in freeze-dried native (NS) and gelatinized (GS) potato starch systems at 70°C. Water sorption isotherms were studied in a wide range of relative humidities (RH) and Guggenheim-Anderson-de Boer (GAB) model was applied. Thermal transitions were studied by differential scanning calorimetry; molecular mobility was estimated through time-resolved 1H NMR, and Maillard reaction was followed photocolorimetrically. In NS systems, the Maillard reaction rate was inversely dependent with the increase of RH. These results are due to a heterogeneous distribution of water and reactants within the starch matrix. In GS systems, the rate coefficient of the Maillard reaction increased up to RHs between 75% and 84% and then decreased at higher RH values. In this case, Maillard reaction rate could be related to the physical properties of the matrix: T g, water sorption, and water mobility can be relevant tools to predict the Maillard reaction rate-dependence on water content.