Sweet Potato Varietal Evaluation Trial for Food Nutritional Values | Chapter 05 | Advances and Trends in Agricultural Sciences Vol. 3
Aim:
The aim of this work was to explore the nutrients, minerals, beta-carotene and
total carotenoid contents of five sweet potato varieties viz., Agric orange
flesh, Agric white, Red skin, Orange flesh and T.U. purple and present the
findings in a language that the average reader can understand. This will help
consumers to appreciate what they are feeding their bodies with when they eat
the different varieties of sweet potato.
Study Design: The sweet potato vines
at six week stage were cut into 1.2 m each and transplanted in parallel lines
on the same 1.2 m x 2.6 m bed, spaced about 0.52 m from each other in Dukumah
Garden. There were five such beds and vine cuttings transplanted in the same
order on each bed. The essence was to provide the same soil and environment so
that at harvest, the content of their nutrients, mineral salts and other food
factors can be compared.
Study Site: The study, which took
four months, was conducted in the Dukumah Garden in Bolgatanga Municipality
(10.7875°N, 0.8580°W) of the Upper East Region of Ghana.
Methodology: The sweet potatoes were
harvested four months after transplanting on the same day. Samples of the
various varieties were collected, parceled, appropriately labelled and
hand-delivered to the Food Chemistry Laboratory of Kwame Nkrumah University of
Science and Technology for proximate analysis (%), total carotenoids and
beta-carotene concentrations in milligrammes per gram (mg/g) and concentrations
of the minerals, namely magnesium (Mg), sodium (Na), potassium (K), calcium
(Ca), iron (Fe) and zinc (Zn) in milligrammes per kilogramme (mg/kg).
Results: All the five varieties of
sweet potato were found to be nutritious. Protein content ranged from 3.82% in
the Agric white variety to 0.11% in Agric orange flesh. Fat content ranged from
4.84% in orange flesh variety to 1.74% in red skin. Crude fibre content was between
1.77% in Agric orange flesh and 0.10% in T.U. purple. Total carbohydrate varied
from 23.2% in Agric orange flesh variety to 15.8% in Agric white one. Moisture
was high in all the varieties, ranging from 75.78% in Agric white variety to
71.04% in Orange flesh one. The Orange flesh variety had the highest ash
content of 1.56%. All the varieties contained high concentrations of Mg but low
concentrations of Na and K. The highest concentration of Ca (8250.70±0.06
mg/kg) was recorded in T.U. purple. The concentrations of Fe in the sweet
potato varieties decreased in the following order: T.U. purple>Red
skin>Orange flesh>Agric orange flesh>Agric white. The highest
(123.12±0.00 mg/kg) and the lowest (33.10±0.00 mg/kg) Zn concentration were
recorded in the orange flesh and Agric white varieties, respectively. The
concentration of beta-carotene (mg/kg) in five sweet potato varieties was in
the following order: Agric orange flesh<<Agric white<Red
skin<Orange flesh<T.U. purple.
Conclusion: The five varieties of
sweet potato were found to be rich in proteins, total carbohydrates and fats.
They were observed to vary in macro- and micronutrients, beta-carotene and
total carotenoids contents. T.U. purple variety was identified to be the
richest source of Ca and beta-carotene. Thus, the sweet potato varieties may be
of considerable importance in ameliorating nutrient, mineral as well as
beta-carotene malnutrition in poorly resourced areas of the developing
countries.
Author(s) Details
Abonuusum Ayimbire
Department of Ecological
Agriculture, School of Applied Science and Arts, Bolgatanga Polytechnic,
P.O.Box 767, Bolgatanga, Ghana.
Abdul-Rahaman Saibu Salifu
Department of Ecological
Agriculture, School of Applied Science and Arts, Bolgatanga Polytechnic,
P.O.Box 767, Bolgatanga, Ghana.
Christina Abi Atinga
Department of Hotel Catering
and Institutional Management, School of Applied Science and Arts, Bolgatanga
Polytechnic, P.O.Box 767, Bolgatanga, Ghana.
Delali Polycarp
Department of Hotel Catering
and Institutional Management, School of Applied Science and Arts, Bolgatanga
Polytechnic, P.O.Box 767, Bolgatanga, Ghana.
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