Feasibility Of Small Scale Production Of Solar Dried Potato (solanum Tuberosum) Flour And Its Potential Food Uses In Kenya

The main aim of this study was to develop a simple and low-cost process for production of an acceptable potato flour, and to identify its potential food uses in Kenya. Sulphited raw potato slices, sulphited blanched potato slices and cooked potato shreds, all from the variety Desiree were each dried in three potentially commercial natural air convection solar driers with the aim of establishing the most appropriate drier and best pre-treatment of potatoes for production of flour. All three driers were found to achieve the required moisture content of approximately 10% in all the products within a 24 hr period during favourable weather. Results further showed that drying of either the blanched slices or the cooked shreds did not offer any technological or product quality advantage over drying of the raw slices. Dehydration of raw slices in the two natural air convection solar driers was considered to be more suitable for flour production than the wind-assisted drier tested for comparison. The dried raw slices were milled in comparative trials using the experimental. Buhler roller mill and the commercial Ndume hammer mill. Because of its lower capital costs arid ready availability in Kenya's rural areas compared to the roller mill, and the fact that it produced flours within acceptable particle size range, the hammer mill was adopted for all the, subsequent milling of the dried slices. Chemical and nutritional evaluations demonstrated that the raw flour had a reasonable level of protein containing sufficient amounts of all the essential amino acids except methionine and cystine.' Although the protein of the raw flour showed low digestibility in in vitro studies, little influence of the flour was observed following incorporation into food mixtures. The amino acid scores for lysine, threonine, tryptophan and even those for methionine and cystine were much higher than for the corresponding amino acids in food items considered by FAO/WHO to be for low-cost diets. The essential amino acid index was quite high for plant proteins. The discriminant computed-protein efficiency ratio (DC-PER)was comparable to that of Pure potato protein and casein before correction for' digestibility which was rather low. The net dietary protein energy ratio (NDpER) showed the flour to be moderately balanced in terms of protein and energy. The flour would also be a good source of the minerals potassium, phosphorus and magnesium . The functional properties of the flour were evaluated through incorporation into conventional yeast bread and the traditional foods chapati (unleavened bread), mandazi (doughnuts), ugali (stiff porridge), uji (thin porridge) And irio (a mashed mixture of cooked potatoes, maize, beans and green leafy vegetables). Bread with reasonable loaf volume and consumer acceptability was obtained following incorporation of potato flour up to 10'10 (w/w) into white wheat f l.our . Beyond this level of potato flour incorporation, loaf volume decreased although the bread was still organoleptically accept8hle. Higher levels of up to 40% (w/w) potato flour were acceptable in wheat chapatis and mandazis, and in maize ugali and uji. Replacement of fresh potatoes with equivalent amounts of potato flour in irio was found to produce a similarly acceptahle product. Addition of potato flour improved the DC-PER of ugali, uji, chapati and mandazi, but slightly reduced that of bread. The DC-PER of irio containing potato flour was comparable to that of the fresh potato-based product. Moreover, the incorporation of potato flour improved the NDpER of a 11.the products tested. Finally, an economic feasibility analysis demonstrated that simple processing of potatoes into flour could be a profitable enterprise in Kenya. The potato flour could be sold at prices that are competitive with common non-wheat flours for partial substitution of imported wheat flour in bread and other wheat-based products
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