Effect of Hydrothermal Processing on Carotenoids, Tocopherol, Fatty Acids and Oxidative Parameters of Palm (Elaeis guinensis Jacq) Oil

Abstract

The study investigated the impact of hydrothermal processing on carotenoids, total tocopherol, fatty acids and oxidative changes in palm (Elaes guinensis) oil. The oil samples were subjected three thermal processes namely boiling (oil with water), stir-frying (oil without water) and batch frying (frying plantain in oil). In each of the thermal operations, samples of oil were withdrawn at time interval for analysis. The oil samples obtained from each operation analysed for chemical parameters using standard methods, fatty acid profile analysed using gas chromatography, carotenoids by spectrophotometric methods after separation by open column chromatography and tocopherol by colorimetric method. The results indicated that stir frying and boiling processes caused a drastic decrease in the carotenoid within 2mins, β -carotene and tocopherol decreased by 50 % within 100 min of processing. The peroxide value and thiobarbituric acid values increased from 8.5 to 118 meq/kg and 2.23 to 7.59 (240 %) respectively. From batch frying, peroxide value, free fatty acids and acid value increases from 9.48 to 33.21 meq/kg, 0.93 to 1.42 and 1.85 to 2.82, correspondingly as frying time was increased. The trans fatty acids was discovered to be present due to increase frying time. The study revealed that heat treatment to which palm oil is subjected especially during food preparation could lead to loss of lipophilic vitamins and essential fatty acids with formation of trans fatty acid; and also, oxidative deterioration of the oil. Hence, repeatedly used vegetable oil should be constantly analysed as it may be detrimental to nutrition and health of consumers.