IMPACT OF PROCESSING TECHNIQUES ON NUTRITIONAL COMPOSITION AND ANTI-NUTRIENT CONTENT OF GRAIN AMARANTH

Abstract

Grain amaranth (Amaranthus albus) is a pseudo cereal consumed in various parts of the world. It has attractedincreasing interest over recent decades because of its nutritional and functional properties. Reducing antinutrientslevel in the grain prior to consumption increases nutrient utilization and absorption, and more soincreases the bioavailability of nutrients. Therefore, this has lead to an advanced requirement to haveadvanced processing technologies to improve on bioavailability and utilization of nutrients Amaranth grain canbe boiled, popped, roasted, or milled to make gruel for consumption. This study investigated the impact of dryand wet heat processing techniques on the nutrient and anti-nutrient contents of grain amaranth. Proximatecomposition, anti-nutrients content, protein digestibility and starch gelatinized were determined. The dryheating processes used included roasting and popping while the wet heating techniques included boilingwhole grains and slurries. Generally, the effects of dry and moist heat processing with regards to loss andretention of the nutrients differed significantly (p>0.05), with only the roasting retaining more of the nutrientsthan boiled seed flour. Processing did not have significant effect (p>0.05) on proximate composition of grainamaranth. A pronounced reduction in the anti-nutrient content (tannins, oxalates, phytates) was observed inthe case of boiling as compared to roasting and popping. Popping, boiling and slurring resulted in 78.0%,86.2%, 92.6% increase in protein digestibility respectively whereas roasting reduced it to 66.3% as comparedto raw grains (74.8%). Dry heating resulted in partial gelatinization of starch unlike wet processing whichshowed complete gelatinization. Therefore, processing techniques are required to reduce on the anti nutrientfactors and promote utilization of nutrients by the consumer particularly the children, lactating mothers, HIVaffected and infected, elderly and other people who may be at risk.