| dc.description.abstract | 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 | en |
