Nutritional and functional properties of a complementary food based on Kenyan amaranth grain (Amaranthus cruentus)

Abstract

The objective of this study was to determine the nutritional and functional properties of Amaranthus cruentus grain grown in Kenya for preparation of a ready-to-eat product that can be recommended as infant complementary food. Amaranth grains were subjected to steeping and steam pre-gelatinization to produce a ready-to-eat nutritious product with improved solubility during reconstitution. The effect of processing on the functional and nutritional properties of amaranth grain was analyzed. Two blends were prepared from raw and processed amaranth grains. Standard procedures of Association of Official Analytical Chemists (AOAC) were used to determine the proximate chemical composition. High Performance Liquid Chromatography (HPLC) was used quantify amino acid, water soluble vitamins, α-tocopherols and phytates, while Atomic Absorption Flame Emission spectrophotometry was used to determine the mineral element composition. Fatty acid composition was determined using Gas Liquid Chromatography (GLC). Tannin composition was determined using vanillin hydrochloric acid method. The overall results indicated that processing amaranth grain did not significantly affect its nutritional and physicochemical properties. Amaranth grain product was rich in protein with 0.5 g/10g of lysine, a limiting amino acid in cereals, and methionine, a limiting amino acid in pulses. The product had good amount 44.4 mg/100g of α-tocopherols important for infant development. The product was also rich in oleic acid (36.3%) and linoleic acid (35.9%) with some amounts of linolenic acid (3.4%) that are important for infant growth. It also had good amounts of minerals of importance such as potassium (324.4 mg/100g), phosphorous (322.8 mg/100g), calcium 189.1 (mg/100g), magnesium (219.5 mg/100g), iron (13.0 mg/100g) and zinc (4.8 mg/100g). Considering amaranth grain product fed to infant three times a day, at a reconstitution of 15% product, the levels of magnesium, manganese and tocopherols were far above the recommended intakes, while protein, phosphorous, iron, zinc, riboflavin and niacin were above the average requirements. Therefore, reconstituting the product with milk would enrich the deficient nutrients, especially for iron and zinc which are crucial nutrients for infants. The processing method is a practical approach aimed at combating the problem of malnutrition among infants and young children in Kenya and other developing countries. The product developed in this study would also be appropriate for use in geriatrics care and also in immuno-compromised individuals. The technique in this study can be easily adopted at both household and village levels to produce high protein-energy weaning food to help enhance the nutritional status of Kenyans.