Properties of rehydrated freeze dried rice as a function of processing treatments

Freeze dried (FD) rice is ideally suited for long-life, ready-to-use applications such as emergency foods and military rations, due to its very low moisture content, light weight and rapid rehydration properties. This study ascertained the influence of rice type and processing conditions on the structural and functional properties of FD rice, to better understand the impacts of freeze drying on expected eating quality. It determined rehydration capacity, breakage, texture and visual morphology. Cooking methods influenced the physicochemical properties of FD rice with distinct differences between parboiled and non-parboiled rice. FD non-parboiled rice could have over 50% of grains broken during processing. The steam oven cooking method gave both the lowest rehydration capacities in parboiled rice (193%), and the highest rehydration capacity in non-parboiled rice (367%). FD parboiled rice was more similar in texture to the freshly cooked equivalent compared to the non-parboiled rices. Parboiled rice is thus more suited to the FD process.