NEW GENERATION OF HEALTHY SNACK FOOD BY SUPERCRITICAL FLUID EXTRUSION

A supercritical fluid extrusion (SCFX) process has been successfully developed for the production of a novel healthy snack containing 40-60 wt% protein with unique porous structure and texture. Supercritical carbon dioxide (SC-CO2) injection rate and product temperature at the die were found to be critical to control the expansion and texture of the final product. Maximum cross-sectional expansion was obtained at 0.3 wt% added SC-CO2, whereas more uniform internal structure was achieved at 0.7 wt% SC-CO2 level. As whey protein concentrate (80 wt%) concentration was increased from 52.8 to 78.2 wt% in the formulation, the cross-sectional expansion of baked and fried products increased by 65.8 and 44.4%, respectively. It was observed that lower viscosity of whey protein compared with starch decreased expansion but helped enhance further expansion during post-extrusion drying. The finding showed that an extrusion process at the temperature below protein denaturation temperature using SC-CO2 can help to prevent hard texture due to the thermosetting property of whey protein and to create a uniformly expanded structure. The textural properties of SCFX chips were comparable to commercial extruded or fried chip products. PRACTICAL APPLICATIONS The American snack market is one of fast-growing markets in the world as snacking becomes more popular. Because of the increasing concerns about health, there is also an increasing demand for new healthy snacks as an alternative for fried starch-based snacks with low nutrient density. This study shows the potential of supercritical fluid extrusion (SCFX) technology for healthy snack food production containing whey protein. SCFX chips had uniform cellular microstructure that cannot be obtained using conventional steam-based extrusion. As supercritical carbon dioxide can deliver certain flavors, an expanded snack not only with high nutrient density and unique texture but also with encapsulated flavors can be produced using the SCFX process and can be marketed as a novel healthy snack.