Impact of tempering process on yield and composition of quinoa flour

Quinoa kernels are generally whole-milled due to their small kernel size. However, roller milling allows the separation of the starchy perisperm from the protein- and fat-rich bran fraction. Both fractions can be used for specific food applications. Studies have focused on roller milling of quinoa but information on tempering is rather limited. This study investigates the impact of different tempering conditions on roller milling of quinoa. Three types of commercially available quinoa seeds were roller-milled on small scale by a Brabender Quadrumat Junior. Two levels of tempering time (8 and 20 h) were combined with three levels of tempered moisture (13, 15 and 17%). Flour yield was recorded and the obtained flour was characterised by moisture, ash and protein content, flour colour index (FCI) and particle size distribution (PSD). An increase in tempered moisture reduced the flour yield, while a change in tempering time had no effect on two out of three samples. Flour composition depended on the combination of tempering conditions but increasing tempered moisture generally resulted in a better bran-perisperm separation. Differences in kernel properties were reflected in the PSD: small kernels created a coarser flour with higher ash and protein content.