Modified Test Kit for Detecting Polar Compounds and Evaluating Their Distribution in Reused Frying Oil

Polar compounds in repeatedly used frying oil pose significant health risks to consumers. This study aimed to develop an improved test kit for detecting polar compounds in used frying oils and to compare the distribution of polar compounds across different types of cooking oils. The modified test kit was evaluated using six types of oils, which were heated and tested against a standard method with 100 samples. The modified test kit demonstrated an accuracy of 92.00%, sensitivity of 88.09%, specificity of 94.82%, positive predictive value of 92.50%, and negative predictive value of 91.66%. The polar compound distribution was analyzed in six types of oils: palm oil, coconut oil, rice bran oil, sunflower oil, canola oil, and soybean oil. Coconut oil was found to be the least suitable for frying due to the rapid formation of polar compounds. In contrast, rice bran oil, sunflower oil, canola oil, and palm oil were more suitable for frying, with polar compound contamination occurring only after more than 80 h of use. These findings can assist food service operators in extending oil usage while ensuring consumer safety.