| Blends of potato pellets and parboiled rice were puffed using a rice cake machine to produce a new product---rice-potato cakes for improved flavor. Potato pellets were prepared by grinding the strands obtained by extruding potato flour with a twin-screw extruder and sifting the grounded particles on mesh size of 7, 8, 10, and 16. The experiment was a 3 x 3 x 3 x 4 x 2 factorial design with two replications. Rice and potato pellets were blended in three ratios: 100/0, 75/25, and 50/50 and tempered to three moisture contents: 8.5, 9.5, and 10.5%. The blends were puffed at 3 heating temperatures (221, 229, and 237°C) and 4 heating time periods (5, 6, 7, and 8 s). More than 20 cakes were sampled per treatment to evaluate the cakes' qualities of color, texture, and weight loss. SEM (Scanning Electronic Microscopy) was conducted to study the microstructure of puffed cakes. All the four processing variables had significant effects on the quality of rice-potato cakes. Most of the interaction effects were also significant. In general, higher heating temperature, longer heating time, higher moisture, and lower rice content led to rice-potato cakes with higher specific volume, lighter, more reddish, more yellowish color, firmer texture, and lower weight loss. |
