Evaluation of infrared assisted freeze drying for strawberry snacks: drying kinetics, energy efficiency and quality attributes

Feasibility of infrared assisted freeze drying (IRAFD) was evaluated for production of the strawberry snacks. Infrared (IR) radiation provided the driving force of ice sublimation during freeze drying (FD). Different IRAFD conditions were tested, including the continuous IRAFD-1.6 kW/m(2) and IRAFD-1.6 kW/m(2) at different weight reductions (20%, 40%, and 60%). Conventional FD had a total drying time of 691 +/- 19 min, whereas continuous IRAFD significantly reduced the drying time to 309 +/- 32 min. Continuous IRAFD also reduced the amount of consumed electrical energy by 42% compared to that of FD. A long duration of IR radiation produced a soft texture in the snacks. Drying kinetics were analyzed using various models, including the Page model, exponential model, and Henderson and Pabis model. The Page model provided the best fit to the experimental drying curve. This study showed the potential of IRAFD in producing value-added fruit snacks with good textural quality and efficient use of energy.