Determination of Quinoa(Chenopodium quinoa Willd.) hardness by an Experimental Milling Method
The hardness of grains can help determine the optimal harvest time and their postharvest handling. This study was conducted with the objective of developing an experimental methodology to indirectly determine the hardness of quinoa (Chenopodium quinoa Willd.) seed. Five quinoa samples (Blanca Canadá, BT, RT, Ontifor and NT) were evaluated in terms of moisture (%), hectoliter weight (kg∙hL-1) and hardness (breaking resistance). In order to determine the last-mentioned variable, 200 g of seed were sieved in No. 10, 14 and 18 meshes with a retention tray underneath; this was done in order to homogenize the size. Quinoa retained on each sieve was weighed. From mesh 14, which was the one with the highest retention (80 %), 30 g were ground for 2 s and sieved in No. 14, 18, 20, 24 and 30 meshes, with a retention tray underneath. The fractions obtained were weighed and the retention percentages of each sieve were obtained. To classify the hardness of the grain, a hedonic scale was developed. RT, BT and Ontifor were categorized as slightly hard, and Blanca Canadá and NT as slightly soft. The Ontifor sample showed the highest moisture and hectoliter weight, while NT had the lowest moisture percentage and the softest grain. The methodology used to determine hardness is easy to use both in the field and industry and may be useful in other small grains.