Deep frying is commonly utilized for food preparations
such as frozen pre-fried foods, snack foods and fast foods.
Fried foods are far more popular today in many places and
this can be observed from the rapidly increasing number of
fast food restaurants and vendors in the last few decades.
Deep frying of foods at high temperature creates the welcome
special flavor, golden brown color and crispy texture. It is
noted that frying causes oil to undergo hydrolysis, oxidation
and thermal reaction, and consequently numerous byproducts
such as free fatty acids, alcohols, cyclic compounds, dimers
and polymers(1) can be produced. Some products of decomposition
in used oil have been identified to have adverse effects
on human health(2-4), as they may have a higher chance of
absorption into the fried foods(5). Therefore, it is important to
understand the factors affecting the deterioration of frying oil
and to monitor the quantity of products of decomposition for
ensuring the quality of fried foods