Nutritional composition of some selected, unprocessed amaranth grain (Amaranthus spp) varieties in Nigeria

The Amaranth grain is highly nutritious, yet it is hardly utilized in Nigeria. This study seeks to evaluate the nutritional composition of the various Amaranth grains available locally within the country. Five identified varieties were obtained from a research institute in Nigeria and a variety from the market in Ondo State, Nigeria. The six varieties were sorted separately and cleaned manually prior to grinding into flour and then subjected to chemical analysis which included proximate content, minerals, and anti-nutritional composition. An investigation of the constituting proximate, minerals and anti-nutritional compositions of the grain flours was conducted, using standard procedures. Proximate composition was determined using the Association of Official Analytical Chemists (AOAC) methods, carbohydrates were determined by difference, energy content was determined using bomb calorimetry model, mineral analysis were done using atomic absorption spectrophotometer and flame photometer while the anti-nutrients were determined using potassium permanganate titration method and spectrophotometrically. The results were analyzed using ANOVA (p < 0.05) which showed significant difference between the moisture content of the market sample and other types (9.50-12.13%). Also, the fat and crude fibre contents of Amaranth grain flour ranged from 5.84 to 21.06 % and 0.61 to 2.07 %, respectively. Though the protein contents of the flour samples were not significantly different (14.36-16.03%) from each other, the mineral composition (calcium 193.34-247.91 mg/100g, magnesium, 65.59-73.48 mg/100g, manganese 6.13-13.24 mg/100g, sodium 360-435 mg/100g) was relatively high. The anti--nutrient composition showed that the varieties were low in phytate and the values ranged from 0.21-1.74 mg/100g, the oxalate level of the varieties averaged 15.02 mg/100g for the six samples, the tannin level ranged from 9954.6 to 13565 mg/100g. The study showed that Amaranth grain flour is potentially a food commodity item for value addition either by its lone use or in composite flour formulation.