The repetitive frying of food items in the same plant edible oil in order to
reduce the cost is a common practice among street food vendors. However, repeated
heating and frying can cause spoilage of oil by altering the physicochemical and
nutritional qualities of cooking oils. The fried food items in the reused and reheated
cooking oil lead to various diseases such as cancer, cardiovascular diseases, diabetes,
atherosclerosis, etc. The health risks associated with using reused and reheated cooking
oil are causing a significant concern in the medical world. The focus of this study was
to identify the structurally modified fatty acids and formation of various toxic
compounds in the reused and reheated cooking oil samples derived from plant-based
and animal-based fast food items for comparative analysis. Fatty acid methyl esters
(FAMEs) were analyzed by gas chromatography-mass spectrometry (GC-MS). The
major toxic compounds detected from plant-based oil samples were phorbol (2.06%)
and campesterol (50.06%). On the other hand, from animal-based oil, hentriacontane
(50.8%), trimethylsilyloxytetradecane (70.2%), and estra-1,3,5 (10)-trien-17-β-ol
(12.40%) were detected. Also, the amino acid profiling of the oil samples was
performed using HPLC. Higher concentrations of the amino acids found were lysine
(4.30μg/mL in plant-based oil samples and 5.24μg/mL in animal-based oil samples),
phenylalanine (3.03μg/mL in plant-based oil samples and 40.6μg/mL in animal-based
oil samples) and aspartic acid (9μg/mL in plant-based oil samples and 10.6μg/mL in animal-based oil samples). The outcome of this study infers that continuous
consumption of food items deeply fried and heated with re-used oils would indirectly
lead to complications in humans, and this comparative study reflects the distinction
between the types of diets, animal-based and plant-based, and also between unused oil
stock and repeatedly used cooking oil stock.
Keywords: Amino acids, Animal and plant-based foods, Fatty acids, GC-MS, HPLC, Repeated over-heated oil.
