Development of a continuous method for puffing Amaranth (Amaranthus spp.) seeds

Amaranth (Amaranthus spp.) is a nutritionally dense pseudocereal grown mostly in South America and Asia. Traditionally amaranth seeds are puffed using a hot skillet. Besides being a batch system, in this process there is little control over the temperature and the residence time of the seeds. We have developed a continuous technique for puffing amaranth seeds using a single-screw extruder with a tapered screw without a die. With this technique we could control the temperature and the residence time for puffing the seeds. It was found that the puffing efficiency of amaranth seeds was a function of temperature and screw speed. The maximum efficiency of 86% was achieved at a barrel temperature of 290C and screw speed of 125 rpm. Sensory analyses with an untrained panel of 33 subjects using samples generated at conditions with puffing efficiency above 75% showed that the sample processed at 250C and 75 rpm was the most acceptable in terms of various sensory attributes and overall liking.