Mathematical Modeling of Browning Induction Period in Drying Onion as Influenced by Temperature, Equilibrium Relative Humidity, and Inhibitor

This work focused on the browning induction period (BIP) during onion drying and understanding the impact of selected static conditions and cyclodextrin addition on the BIP. Under static conditions (between 40 and 80 degrees C and betwen 0.11 and 0.98 equilibrium relative humidity, ERH), the BIP due to nonenzymatic reactions was evident but apparently reduced by enzymatic browning reactions at 40 degrees C. Cyclodextrin usually inhibited browning from both reactions under some conditions, whereas it stimulated browning under the combined conditions of an ERH of 0.58 and 0.75 and temperatures of 40 and 60 degrees C. The proposed interaction polynomial models successfully cover both enzymatic and nonenzymatic browning experienced at the initially low and then high temperatures used in food drying. These models can be useful for a food drying process design to minimize browning.