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

Abstract

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 thermooxidative 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.Abbreviations: DMPS, dimethylpolysiloxane; PUFA, polyunsaturated fatty acids Eur.

Monitoring the physicochemical features of sunflower oil and French fries during repeated microwave frying and deep-fat frying

“…Consumer demand for healthier products has caused a significant increase in research in the area of fried foods. Many of these studies have focused on the reduction of oil uptake (Ziaiifar et al, 2008) and oil degradation (Aladedunye, 2015) while keeping the desired characteristics of fried foods during deep fat frying. Deep fat frying is defined as the drying and cooking process of food through contact with oil at a temperature of 120 to 190 °C.…”

“…There are many variables affecting the oil degradation. The process of frying is counted as one of the most important factors affecting frying oil quality beside factors like properties and composition of the oil, and the interaction of the food with the frying oil (Aladedunye, 2015;Rossell, 2001). The physicochemical changes occurring in different types of oils during deep frying have been extensively studied by researchers (Siddique et al, 2010;Serjouie et al, 2010;Rehab and El Anany, 2012;Mishra and Sharma, 2014;Zhang et al, 2016).…”

Effects of oil-water mixed frying and pure-oil frying on the quality characteristics of soybean oil and chicken chop

“…These reactions give rise to deterioration of oil composition (Brühl, 2014), and subsequent generation of a wide variety of volatile and nonvolatile compounds (Choe & Min, 2007), which ultimately alter the sensorial, nutritional and functional properties of the oil (Zhang et al, 2012;Aladedunye & Przybylski, 2013;Crosa et al, 2014). Since food absorbs a remarkable amount of oil during frying, making oil an ingredient of the final product (Al-Khusaibi et al, 2012), oil degradation has adverse effects not only on properties of fried foods, such as sensory attributes, nutrition and shelf-life (Dobarganes et al, 2000;Pawar et al, 2013;Aladedunye, 2015), but also on food safety, thereby affecting human health (Stier, 2013;Urbančič et al, 2014;Wang et al, 2015).…”

“…In view of frying method affecting the extent of oil deterioration and the overall quality of oil (Zhang et al, 2012;Aladedunye, 2015), it is important to develop alternative technologies to conventional frying, meanwhile maintaining fried foods' desirable sensory characteristics. Among possible methods, oil-water mixed frying is to use the mixture of oil and water in a fryer.…”

Determination of Total Polar Compounds in Frying Oils by PE‐Film‐Based FTIR and ATR‐FTIR Spectroscopy

“…Fried foods possess a unique aroma, taste, and textural properties that cannot be obtained through other cooking techniques. During frying, triacylglycerols rapidly undergo hydrolysis, oxidation, polymerization, and pyrolysis given the high temperature used in this cooking method (150–180 °C) . Total polar compound (TPC) contents are the best indicators and the most common parameters for the quality evaluation of frying oils .…”