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.
