Volume 8, Issue 4, August 2020, Page: 117-120
Investigation of the Effects of Repeated Frying on the Quality of Vegetable Oil
Maduelosi Ngozi Jane, Department of Chemistry, Rivers State University, Port Harcourt, Nigeria
Cookey Grace, Department of Chemistry, Rivers State University, Port Harcourt, Nigeria
Received: Sep. 22, 2019;       Accepted: Oct. 18, 2019;       Published: Aug. 31, 2020
DOI: 10.11648/j.ajac.20200804.13      View  159      Downloads  70
Abstract
Refined vegetable oil (Kings brand), was purchased from Mile 3 Market, Port Harcourt, Nigeria and was repetitively used in frying Akara balls for a period of 24 hours, at intervals of four hours per day, for six days. The effect of heat and repetitive use for frying on quality of the oil was monitored by the measurement of the physico-chemial parameters of the oil after each frying period. The density, % free fatty acid, viscosity, peroxide value and iodine value of the fresh and used oil were determined to investigate the level of deterioration. The results obtained show that the values of the parameters increased with frying time except that of iodine value which decreased with frying time. The free fatty acid value increased from 0.06 -.56%, density increased from 0.900-0.910 g/ml, viscosity increased from 23.33-28.31mm2/s, peroxide value increased from1.988-4.879meqO2/Kg and iodine value decreased from 43.35 – 29.83wijis. These changes are attributed to the destruction of the chemical structures of the triacylglycerols and formation of new products in the oil by heat. The increase in the density and viscosity shows that as frying progressed, denser and higher molecular weight compounds are formed thereby rendering the used oil more viscous. The increase in peroxide values may be due the formation of peroxides as the primary products of oxidation. The formation of peroxides leads to loss of unsaturation in the oil which is seen as a reduction in iodine value of the oil. The sweet aroma of the oil was also lost as frying progressed as a result of de-esterification of the oil and formation of secondary oxidation products that impart off-flavours to the oil. The findings show that repeated use of vegetable oil for frying leads to deterioration/degration of the oil.
Keywords
Oxidation, Physico-Chemical Parameters, Vegetable Oil, Frying, Akara Balls, Heat
To cite this article
Maduelosi Ngozi Jane, Cookey Grace, Investigation of the Effects of Repeated Frying on the Quality of Vegetable Oil, American Journal of Applied Chemistry. Vol. 8, No. 4, 2020, pp. 117-120. doi: 10.11648/j.ajac.20200804.13
Copyright
Copyright © 2020 Authors retain the copyright of this article.
This article is an open access article distributed under the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0/) which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
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