Effect of repeated heating on Chemical Properties of selected edible plant oil and its Health Hazards

Authors

J Prarthana, Department of P.G Studies & Research in Biotechnology, Sri Dharmasthala Manjunatheshwara College (Autonomous), Ujire, Karnataka, IndiaFollow
Nischitha Nischitha, Department of P.G Studies & Research in Biotechnology, Sri Dharmasthala Manjunatheshwara College (Autonomous), Ujire, Karnataka, India
Shraddha Shraddha, Department of P.G Studies & Research in Biotechnology, Sri Dharmasthala Manjunatheshwara College (Autonomous), Ujire, Karnataka, India
Ramith Ramu, Department of Biotechnology and Bioinformatics, JSS Academy of Higher Education and Research, Mysuru-570015, Karnataka, INDIA

Abstract

Increase in the cost price of edible oil, has forced to reuse the cooking oil especially in frying. Repeated cooking of oil brings about lot of structural changes ideally not suitable for consumption. The present study aims at comparing the structure and chemical changes like acid value, peroxide value, saponification, iodine value of three different commonly used edible oil viz sunflower oil, coconut oil & rice bran oil after successive heating & cooling. Oils were heated four times for 45 minutes, followed by repeated cooling for 2 hours. The results indicates that the acid values of all three oils (0.32- 1.36mg KOH/g)were in line with recommended standard values. The saponification values were gradually increased after every heating in rice bran oil, after the third heating the values crossed the standard limit(252- 278.10mgKOH/g in Coconut oil, 184.23-198.00mgKOH/g in Sunflower oil and 190.81-199.99mgKOH/g in Rice Bran oil.). In coconut and sunflower oil the peroxide values exceeded the standard limit after second heating whereas, in rice bran oil the values exceeded after the first heating implying rancidity releasing free radicals upon heating, peroxide value of Coconut oil (1.00-52.00meq/kg), Sunflower oil (1.00-47.00meq/kg) and Rice Bran oil (10.00-160.00meq/kg), increasing peroxide value over repeated heating indicates higher degree of oxidative rancidity. First heating of all oil showed low acid value indicating stability against peroxidation & rancidity, value increased after repeated heating. Based on the experimental evidence it may be concluded that three commonly used cooking oil, coconut oil, sunflower oil and rice bran oil undergo structural and chemical changes upon repeated heating. However coconut oil and sunflower oil showed structural stability upto second heating, low acid value, saponification ,iodine value and peroxide value were in accordance with reference, where as rice bran oil after first heating showed attributes of oil deterioration with high acid value, saponification, iodine number. Rice bran oil might be good source of other supplemental additives but its repeated heated oil re usage has to be avoided to minimize health risk.

Key words: Edible oil, heating, chemical properties, acid value, peroxide value, iodine value

Recommended Citation

Prarthana, J; Nischitha, Nischitha; Shraddha, Shraddha; and Ramu, Ramith (2023) "Effect of repeated heating on Chemical Properties of selected edible plant oil and its Health Hazards," International Journal of Health and Allied Sciences: Vol. 12: Iss. 3, Article 4.
DOI: 10.55691/2278-344X.1081
Available at: https://rescon.jssuni.edu.in/ijhas/vol12/iss3/4