Curbing thermo‐oxidative degradation of frying oils: Current knowledge and challenges

Deep fat frying is an ancient process with a lot of open questions. This deceptively simple food preparation technique is immensely complicated by the stringent conditions applied during the process, coupled with the inherent lability of the frying medium and the unavoidable meddling from the food materials and other minor components. The various factors affecting frying stability and performance of oil can be broadly categorized into two groups: (1) The external factors, which include frying temperature, frying time, presence of oxygen, and type of fryers, among others, are factors that can be manipulated by the frying operators; (2) the internal or endogenous factors are oil‐specific and include fatty acid composition and their distribution on triacylglycerols, and the amounts and composition of the minor components. Limiting thermo‐oxidative degradation and consequently extending the useful life of frying oils often involves deliberate optimization and control of some of these factors. Available techniques for curbing thermo‐oxidative decomposition of frying oils and the inherent challenges are discussed. Practical applications: This review provides updates to our current knowledge of the salient factors affecting frying performance of oils/fats and specifically highlights both the opportunities for optimization and the accompanying daunting challenges. With this information, institutional frying operators can practically extend the discard point of their frying oils and deliver healthier fried products, while ensuring the safety of the frying facility and the technicians. A trigonal bipyramid model showing the three basic optimizable parameters of frying. The base (striped) represents the optimized region for highest stability of the frying oil and the best quality fried product (operator's target). Higher values (bold lines) tapers off stability while lower values (dotted lines) decrease food quality.