EFFECT OF PRE-TREATMENTS ON THE PHYSICO-CHEMICAL PROPERTIES AND TOTAL CAROTENOID CONTENT OF ORANGE FLESHED SWEET POTATO FLOUR

  • N.P. Ogunka National Root Crops Research Institute Umudike, Abia State, Nigeria
Keywords: Sweet potato, processing, flour, physico-chemical properties, and carotenoid content

Abstract

Orange fleshed sweet potato (OFSP) roots are rich in β-carotene. Due to the possible denaturation of the carotene
during processing, efforts are being made to identify processing methods which will help preserve and retain the
carotenoid content of the product, even after processing. OFSP flour was processed from peeled and sliced
UMUSPO1 variety using pre-treatment methods of boiling, blanching and treating with 0.5% metabisulphite
solution for 10min, while the last sample was without any pre-treatment. The samples were oven dried and
packaged for analysis. Effect of the different pre-treatment methods on their physico-chemical properties and
total carotenoid contents were evaluated. Results show significant differences (p<0.05) in the proximate,
functional and total carotenoid contents of the flour samples. Moisture content ranged from 8.23-8.68%,
carbohydrate (78.45-79.89%), crude fibre (2.57-3.65%), crude protein (6.5-7.18%), fat (1.00-1.17%) and ash
(1.81-1.93%). There were also significant differences (p<0.05) in the functional properties of the samples as a
result of the pre-treatment method applied. Swelling power ranged from 13.64-15.42%, OAC (1.73-3.06%),
WAC (2.65-3.05%), Gelatinization temperature (76.55- 77.54oC) and bulk density (0.61-0.68%). The blanched
flour sample gave the highest amount of post processing total carotenoid content of 7.63mg/100g, followed by
the untreated sample (7.60 mg/100g). Treatment with metabisulphite and boiling gave values of 6.87(mg/100g)
and 6.92 (mg100/g) respectively. Processors of sweet potatoes are therefore encouraged to apply blanching
method to reduce loss of carotenoids associated with processing.

Published
2020-04-30

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eISSN: 0300-368X