Fluidized-Bed Drying-Roasting Process for Developing a Whole Quinoa Snack

Abstract

Recently, quinoa-based products have gain significant attention as valuable ingredients for the food industry. The objective of this work was to chemically characterize a quinoa variety (Chenopodium quinoa Willd., var. CICA) and to evaluate a drying-roasting process for producing a crispy, ready-to-eat snack. The experimental work involved determining thin layer drying-roasting curves for quinoa grains in a fluidized bed dryer at air temperatures ranging from 80 to 140 °C for 30 min, with an air velocity of 0.8 m/s. The CICA variety contained 15.3% protein, 7.5% fat, and 70.6% carbohydrates (on a dry matter basis). Micronutrient contents, determined by Inductively Coupled Plasma-Optical Emission Spectrometry, were K (9819.2 mg/kg), P (4403.6 mg/kg), Ca (974.6 mg/kg), and Fe (25.3 mg/kg), all on a dry matter basis. The initial content of saponins was 0.183% (w/w) characteristic of a bitter variety. Washing reduced this value to 0.108% (w/w), which is an acceptable level for human consumption. This treatment also decreased mineral content by 10-38%. A mathematical model, consisting of local mass and heat balances in spherical geometry with variable diffusion coefficient and shrinkage, was solved using finite differences. An activation energy of 35.7 kJ/mol was estimated by solving an inverse problem, utilizing the complete dataset. Predicted temperatures and average moisture contents showed good agreement with experimental values. To obtain a porous and crispy product, a process time of 10 min at temperatures above 100 °C was required.

Keywords: Chemical attributes; Drying-roasting; Mathematical model; Quinoa; Snack.