Kinetic study of vitamin D2 degradation in mushroom powder to improve its applications in fortified foods

The aim of this study was to develop a value chain approach to address the need for sustainable vitamin D-2 food sources. A combined process of UV-irradiation and air-drying was used to produce a Pleurotus ostreatus powder with a target amount of vitamin D-2 as an ingredient for functional foods. The kinetics of vitamin D-2 degradation was studied as a function of water activity (a(w)) in the range 0.11-0.75 at 30 degrees C, and temperature in the range 20-40 degrees C, at a(w) 0.32. The Guggenheim-Anderson-de Boer equation was applied to model experimental data of moisture content as a function of a(w) at 30 degrees C, and the resulting monolayer water activity was found to correspond to the a(w) level of 0.45. During storage under different environmental conditions, vitamin D-2 degradation followed first-order kinetics. The rate constants ranged from 0.00308 to 0.0121 d(1) at a(w) 0.11 and 0.75 at 30 degrees C, respectively. The Arrhenius equation was applied to calculate the activation energy for vitamin D-2 degradation at a(w) 0.32, which resulted 37.6 kJ/mol. The kinetics data obtained can be used as a basis to design the best formulation strategy to deliver this vitamin with functional foods.