Utilization of beta - carotene - rich sweet potatoes, millet and pigeon peas in development of an alternative bread
Ndung'u, Eunice Njeri
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Vitamin A deficiency is one of the most prevalent and potentially serious forms of micronutrient malnutrition in the world today. Increasing recognition of the negative health effects of vitamin A deficiency has led to increased efforts to develop sustainable solutions to the nutritional problem. Diet diversification is among the food-based approaches used to curb the deficiency today. The aim of the study was to utilize the orange-fleshed sweet potatoes, millet and pigeon peas to develop an alternative bread. The study was based on the idea that food-based approaches are the most suitable for preventing and controlling micronutrient malnutrition. Two flour formulations were used in making the bread variations. The first formulation constituted of 30% wheat, 30% sweet potato, 20% millet and 20% pigeon pea flours. The second one was made up of 40% sweet potato, 40% millet and 20% pigeon pea flours. From each formulation, variations were prepared with and without ascorbic acid as a flour improver. The straight dough method was used to bake the bread. The finished product was analyzed for proximate composition and b-carotene content. Sensory evaluation was done using descriptive and affective tests. The protein content of the samples ranged from 11.0% - 13.5%, with the control bread having the lowest content. The crude fat content was higher in the wheatless alternative bread compared to the variations with wheat flour. Ash content recorded ranged from 2.7%-3.2%. The moisture content of the bread ranged from 33.6% to 38.7%. The calorific value was highest in the control bread having 4.9Kcal/g. The alternative bread with 30% wheat flour both had 4.5Kcal/g. Wheatless variations had calorific value of 4.8Kcal/g. The b-carotene of the samples was lowest in the control bread. The alternative bread with wheat had 3.3mg/g. The wheatless variations had 3.4pg/g. All the four bread variations had above 95% retention levels of -carotene. Sensory results indicated that when 30% wheat flour was used in the alternative bread, the colour was not adversely affected. The geometric characteristics of the bread were affected by use of wheat flour in the formulations. Cell structure scores showed that the bread with 30% wheat flour had a better crumb structure than the wheatless variations. Similar improvement in the scores was noted on the texture quality of the variations. A tender crumb was achieved in the variations with wheat flour. Chewiness scores were better in the variation that had the ascorbic acid. The crumb of the wheatless variations was found to be moist compared to the variations with 30% wheat flour. A slight yeast flavour was noted in the variations with wheat while the wheatless variations had a pronounced yeasty flavour. Moderate aftertaste was observed in the variations with wheat while the wheatless bread had longer aftertaste. Ranking results showed that the variation with 30% wheat flour and ascorbic acid had the best scores. It rated well when compared with the control bread. The findings show that with the use of 30% wheat flour, sweet potato, millet and pigeon pea flours acceptable alternative bread would be prepared. Such bread if promoted for consumption would enhance the intake of pro-vitamin A due to its high b-carotene content. A cost analysis of the composite flour used in the study should be done for commercialization. An analysis of the shelf life of the composite flour in conventional packages could be done as well as a similar study using highly trained panelists.