Development of a Supplementary Food From Selected Local Food Ingredients to Optimize Nutritional and Sensory Qualities

Abstract

Recently there has been widespread consumption and sale of a diverse range of supplementary foods in Kenya. This situation bas been prompted by increase in malnutrition, AIDS and related diseases. and consumer nutrition and health awareness. This study was 1baefore designed to assess the diversity and characteristics of the supplementary foods utilized by the vulnerable groups with a view to document the existing foods in Kenya.

The study also sought to explore ways of harnessing local food ingredients to develop a low-cost supplementary food appropriate for vulnerable groups. Local food ingredients such as finger millet, amaranth grain. pigeon peas. field beans, groundnuts, sweet potatoes, small dried fish (Rostrineobola argentea), amaranth and pumpkin were analyzed for macro- and micro-nutrients; amino acid and fatty acid profiles; bioactive compounds including phenolics, flavonoids, tannins and phytates, and their associated antioxidant and antidiabetic properties. The results of the analyses were used to identify appropriate food ingredients to be incorporated in four prefuninarY formulations from which the tinal supplement was selected as the most preffered by taste panel procedures.

The most acceptable supplement was then analyzed for nutrient contents including macro- and micro-nutrients, amino acid and fatty acid profiles, shelf life and cost of production, the latter being done to estimate the selling price. Results show that the investigated food ingredients possessed high nutritional values. The food ingredients contained 6-44% protein; 8-38% fibre; 11-43% fat; 324-497 kcal energy; and 15-57';\ carbohydrateS. The mineral contents of the food ingredients was in the range of 25-328 mgllOO g calcium, \.0-51 mgllOO g iron, 44-1320 mgllOOg magnesium. 0.2-19 mgllOO g sodium. 60-1105 mgllOO g phosphorus, and \.6-15 mgllOO g zinc.

The indigenous vegetables exhibited 3.2-63 mgllOO g vitamin C and 0.7-5.1 mgllOO g jkaIOtene contt;nts while the grains showed 22-110 J.1g/100 g folic acid, 1.2-17.7 mg/l00 g niacin, 0.1-1.6 mg/l00 g vitamin Bl and 0.1-1.0 mg/l00 g vitamin B2 contents. The total essential amino acid content ranged from 2.7 to 10.4 % in the grains and 0.9 to 12.8% for the vegetables. The levels of the &tty acids in the food ingredients were 4.8-33.6% palmitic, 1.5-9.0% stearic, 2.2-53.9% oleic, 4.5-53.7% linoleic and 0.9-60.4% a-linolenic acids. Fish powder, sunflower seeds, pumpkin seeds, amaranth grain, pumpkin and amaranth leaves exhibited the highest content of essential amino acids.

The total phenolic content of the cereals, legumes, and vegetables ranged from 0.41 to 3.00 g/IOO g DM with amaranth grains (Amaranthus cruentus) and drumstick leaves (Moringa oleifera) significantly exhibiting the highest contents. The phenolic extracts showed promising levels of antioxidant activity expressed as 2,2' -Diphenyl-l-picryl hydrazyl (DPPH) radical scavenging activity of 81-89%, and ferric reducing antioxidant power (FRAP) of 2.33-22.30 mg/mmol Fe[II]. The antidiabetic property was demonstrated by inhibition activities of a-amylase of 10-45% and a-glucosidase of 13-80%. The vegetables exhibited higher content offlavonoids (50-703 mg/l00 g) when compared to cereals, legumes and oil seeds (47-343 mg/100 g). The flavonoid extracts revealed 33-93 % of DPPH radical scavenging capacity, 0.12-2.77 llg/mM Fe[II] of Ferric reducing power, and 19-43% of aglucosidase inhibition activity as well as 14-68% of a-amylase inhibition activity.

The tannin content of the cereals, legumes, and vegetables ranged from 1.53 to 4.35 gllOO g DM. The tannin extracts showed levels of DPPH radical scavenging activity of 77- 90%, FRAP of 47.2-3.6 mg/mmol Fe[II]), a-amylase inhibition activity of 24-40% and aglucosidase inhibition activity of 60-88%. The phytate contents of the grains ranged from 0.29 to 3.23 g/100 g DM. The phytate extracts showed levels of DPPH radical scavenging activity of 61-89%, FRAP of 37.3-3.6 mg/mmol Fe[II]), a-amylase inhibition activity of 20- 72% and a-glucosidase inhibition activity of 12-91 %. The most acceptable supplement was found to be that formulated from amaranth grain, pigeon pea, sweet potato and groundnut in the ratio of 4: 1: 1 :4. This supplement showed high nutritional levels.

The consumption of only 110 g of the product could supply over 50% of the daily nutritional requirements by the vulnerable groups, as recommended by FAOIWHO. The supplement (llOg DM) was found to contain 453.2 Kcal of energy, 12.7% protein, 54.3% carbohydrate, 20.8% fat and 10.2% fibre. The supplement had 93.0 mg/100 g calcium, 172.4 mg/100 g magnesium, 2.7 mg/l00 g zinc and 5.7 mg/100 g iron, as well as 0.8 mgllOO g vitamin BI, 0.2 mg/100 g vitamin B2, 7.9 mg/100 g niacin, 100 llg/lOO g folic acid, and 110 1lg/100 g ~-carotene.

In addition, the supplement had excellent essential amino acid and fatty acid profiles. The shelf life study showed that the supplement could be stored in polythene bags, gunny bags and Kraft paper at ambient temperatures (20-27 °C), 30°C and 35 °c for up to 4 months without significant changes in odor, moisture, peroxide value, fat acidity and reduced ascorbic acid contents. A cost analysis of the supplement was carried out to estimate the selling price of the product if commercially produced. The product could competitively be sold at KES 65.50/kg ($ 0.82/kg). The study concluded that it is possible to formulate a low cost, acceptable and shelf stable supplementary food, affordable by the lower socio-economic vulnerable groups, using food ingredients available locally in Kenya