Researchers at Cornell University’s Institute of Food Science have engineered a new extrusion process for puffed rice they say significantly increases levels of protein and other nutrients compared to traditional steam extrusion. The new method, which utilizes supercritical CO2 in the extrusion process, could be used to create more nutritious snacks and cereals for school lunch programs and other food-insecure populations.
Steam extrusion, the norm in commercial puffed rice, has the disadvantage of exposing the material to high temperatures. In this process, an extruder squeezes rice flour mixed with water through a narrow opening at high temperature and pressure. Upon exiting the nozzle, the rice puffs up as steam expands and escapes. Steam-based extrusion typically occurs at temperatures between 130°C and 180°C, damaging certain proteins, vitamins, flavors and bioactives.