Heating Reduces Vitamin E Content in Palm and Soy Oils

Heating palm oil for 10 minutes (PO1H) caused significant reduction in ?-tocopherol (?-tf), ?-tocotrienol (?-tt), ?-tocotrienol (?-tt) and ?-tocotrienol (?-tt) compared to fresh palm oil (POF). Heated five times palm oil (PO5H) also caused a further reduction in ?-tf, ?-tt, ?-tt and ?-tt. Up to 98% of the three most abundant vitamin E fractions in the palm oil, namely ?-tf, ?-tt and ?-tt, were destroyed by repeated heating. Similarly, heating soy oil for five times (SO5H) also significantly lowered the concentration of all three tocopherols, namely ?-tf, ?-tocopherol (?-tf ) and ?-tocopherol (?-tf), compared to fresh soy oil (SOF) and heated once soy oil (SO1H). However, the latter only managed to significantly lower the level of ?-tf without affecting levels of ?-tf and ?-tf. Up to 60% of ?-tf, which is the most abundant variety of vitamin E in soy oil, was lost upon heating repeatedly for five times. The findings of this study suggest that the extent of vitamin reduction was not only affected by the frequency of heating but varied according to the different vitamin E fractions. Heating appears to have more effect on ?-tf, ,?-tt, ?-tt and ?-tf but less effect on ?- tt and ?-tf