Survey study of frying oils used by food services in the Czech Republic

Frying practices at 135 Czech food services were investigated. The quality of their frying oil baths was evaluated by two rapid tests: Testo 265 (Testo, Lenzkirch, Germany), which determines content of total polar compounds (% TPC) and 3M LRSM (3M, Maplewood, Minnesota, USA), which determines the concentration of free fatty acids (FFA). Firstly, performance of the tests was verified by corresponding standard ISO methods, revealing a relatively good correlation (R2 = 0.87 and R2 = 0.93). Subsequently, these tests were used for a survey study of frying oil baths from food services. The quality assessment has indicated that majority of the samples was of good quality, while only 7% of samples exceeded the limit for total polar compounds (25% TPC) and only 1.5% of samples exceeded the limit for free fatty acids (2.5% FFA) and were at discard point or deteriorated. The study proved that rapid tests are an effective tool for quick evaluation of oil quality. On the other hand, the common practice of food services based on sensorial evaluation of frying baths was found in most cases to be sufficient to maintain the oil quality at an adequate level without the need to use chemical or physical tests.