Determination of total polar compound (TPC) levels in frying oils

Abstract

The deep frying method, that is, the process in which food is cooked by immersion in hot oil, is considered to be the oldest and most common unit operation used in food preparation, especially in the Mediterranean area. During frying process, a wide variety of chemical reactions result in the formation of compounds with high molecular weight and polarity. The repeated use of oil at high temperatures result in several oxidative, polymerization and thermal degradation reactions leading to changes in their physical, chemical, nutritional and sensory properties. Determination of total polar compounds (TPC) is one of the most reliable methods for continuous monitoring of the quality changes in oils during the frying process and is accepted worldwide for the control of frying oils and fats. This study was conducted to determine the levels of TPC in frying oils obtained from various restaurants, cafeterias and school canteens in Istanbul, Turkey. For this purpose, a total of 200 frying oil samples were obtained from various restaurants, cafeterias and school canteens. The samples analyzed for TPC by means of rapid test instrument, Testo 265. According to Turkish Food Codex, 16 frying oil samples obtained from restaurants, 42 samples obtained from cafeterias and 6 samples from school canteens, totally 64 frying oil samples (32.0%) were unacceptable in terms of TPC value.