Refined cottonseed.and hydrogenated palm oils were heated by two metho
ds, conventionally by gas cooker (deep-fat frying) and by microwave en
ergy. Butter was converted to samn and liver slices were cooked with a
mixture of cottonseed oil and margarine using microwave oven and gas
cooker. Quality assurance methods such as acid value, peroxide value,
TBA value and total sterol content of the unheated and heated lipids u
nder study were determined. The time required for butter conversion to
samn or cooking liver slices by microwaves was one-half of the time r
equired conventionally. Exposing the oil samples or samn processing or
cooking liver slices by microwaves caused some hydrolysis to free fat
ty acids and accelerated the formation of hydroperoxides and secondary
oxidation products. In general, the peroxide values of lipids heated
by microwaves were nearly twice as high as that produced by convention
al heating. Gas-liquid chromatographic analyses of fatty acids obtaine
d from the heated oils or stored samn or cooked liver slices indicated
the occurrence of oxidative degradation and production of short-chain
acids.