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 attracted increasing interest over recent decades because of its nutritional and functional properties. Reducing antinutrients level in the grain prior to consumption increases nutrient utilization and absorption, and more so increases the bioavailability of nutrients. Therefore, this has lead to an advanced requirement to have advanced processing technologies to improve on bioavailability and utilization of nutrients Amaranth grain can be boiled, popped, roasted, or milled to make gruel for consumption. This study investigated the impact of dry and wet heat processing techniques on the nutrient and anti-nutrient contents of grain amaranth. Proximate composition, anti-nutrients content, protein digestibility and starch gelatinized were determined. The dry heating processes used included roasting and popping while the wet heating techniques included boiling whole grains and slurries. Generally, the effects of dry and moist heat processing with regards to loss and retention of the nutrients differed significantly (p>0.05), with only the roasting retaining more of the nutrients than boiled seed flour. Processing did not have significant effect (p>0.05) on proximate composition of grain amaranth. A pronounced reduction in the anti-nutrient content (tannins, oxalates, phytates) was observed in the 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 compared to raw grains (74.8%). Dry heating resulted in partial gelatinization of starch unlike wet processing which showed complete gelatinization. Therefore, processing techniques are required to reduce on the anti nutrient factors and promote utilization of nutrients by the consumer particularly the children, lactating mothers, HIV affected and infected, elderly and other people who may be at risk.