Grasas y Aceites, Vol 42, No 3 (1991)

A comparative study on the deterioration of oils by microwave and conventional heating


https://doi.org/10.3989/gya.1991.v42.i3.1243

Radwan S. Parag
Biochemistry Department, Faculty of Agriculture, Cairo University, Egypt

Fawzy M. Hewedi
Biochemistry Department, Faculty of Agriculture, Cairo University, Egypt

Salah H. Abo-Raya
Food Science and Technology Department, Faculty of Agriculture, Cairo University, Egypt

Gamal S. A. El-Baroty
Biochemistry Department, Faculty of Agriculture, Cairo University, Egypt

Abstract


Refined cottonseed oil and hydrogenated palm oil were heated by two methods, i.e., conventionally by gas-cooker and microwaves. Quality assurance methods such as refractive index, color, diene content, acid value, peroxide value, TBA value, iodine value, petroleum ether insoluble oxidized fatty acid content and degree of polymerization were determined. Exposing the oil samples to various heating times and microwave oven power caused some hydrolysis to free fatty acids, accelerated the formation of hydroperoxides and secondary oxidation products. The values from each test increased with both the power settings of microware oven and time of heating. In general, the development of rancidity for refined cottonseed oil heated by microwaves was twice faster than that produced by conventional heating. Also, the chemical values for refined cottonseed oil were much higher than that of hydrogenated palm oil in all cases.

Keywords


Comparative study; Conventional heating Cottonseed oil; Hydrogenated palm oil; Microwave heating; Thermooxidative alteration

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