Quality changes in trans and trans free fats/oils and products during frying

The physico-chemical changes occurring during
simulated frying conditions at 180 °C for 24 h in trans
free speciality fat, trans rich vanaspati and PUFA rich sun-
Xower oil were evaluated. The samples became darker, the
polar components and viscosity increased as the time of
heating increased. The oxidative stability as determined by
peroxide, anisidine values and TOTOX number, increased,
whereas the total unsaturated fatty acids and iodine value
decreased with time of heating in all the samples. The trans
free speciality fat was as stable as vanaspati showing similar
quality parameters, while sunflower oil showed a higher
degree of deterioration. The layered fat used for traditional
products such as Chiroti dough consisted 14% trans fatty
acids (TFA), which was reduced to 4–7%, and correspondingly
18:2 was increased in the product upon frying in sun-
Xower oil. Accordingly, trans fatty acids increased in the
medium from 0 to 7.5%. Chiroti when fried in vanaspati
with TFA 18%, their content in both products (16%) and in
medium (17%) remained similar.