Application of Chromatographic Techniques in the Detection and Identification of Constituents Formed during Food Frying: A Review

Abstract

Frying is one of the most popular food processing methods. However, many physicochemical reactions occur during frying, forming complex products in both the frying oil and the fried food. Chromatographic techniques have been successfully applied to characterize the products formed during food-frying or during a simulated frying process. In this review, the specific products analyzed by gas chromatography (GC) and high-performance liquid chromatography (HPLC) are elucidated in detail. The most studied components are polar compounds (such as volatile compounds, hydrolysis products, oxidized triacylglycerol [TAG] decomposition products, oxidized TAG monomers, sterol oxides, oxygenated TAG polymers, and acrylamide) and nonpolar compounds (such as cyclic fatty acid monomers and trans isomers), which are classified based on their polarity. However, the definite structures of TAG polymers and sterol oxides, and polymers analyzed by GC or HPLC-based methods are only investigated in modeled reactions. Furthermore, some of the sample pretreatments and chromatographic methods are only used to analyze the known products. A number of earlier trace amounts of undetected products need to be investigated by more effective detection techniques. The development of multidimensional chromatographic techniques and elaborate mass spectrometry detectors makes composition analysis possible for the food-frying process, which may effectively promote the development of quality monitoring and nutrition evaluation for the fried foods.

Release Kinetics Studies of Early-Stage Volatile Secondary Oxidation Products of Rapeseed Oil Emitted during the Deep-Frying Process

“…Therefore, the knowledge gained in such a way could be used for example to modify the frying process in order to obtain food with desired taste qualities which might be highly relevant to the food processing industry. Due to the widespread use of gas chromatography in oil volatile degradation products analysis [ 10 ], often due to the necessity to take an oil sample and enrich volatile compounds, it is not possible to observe the changes of early forming volatile products. The most frequently used procedures of volatile fraction analysis include the use of static headspace (SHS) [ 11 ], dynamic headspace sampling (DHS) [ 12 ] and solid-phase microextraction (SPME) [ 13 ] coupled with gas chromatography.…”

Chemosensory Device Assisted-Estimation of the Quality of Edible Oils with Repetitive Frying

“…Canola oil is composed of high monounsaturated fatty acids with 59–61% oleic acid (C18:1). It also contains polyunsaturated fatty acids with 18–21% linoleic acid (C18:2), known as omega-6 fatty acids, as well as 8–11% of α-Linolenic acid (C18:3), known as omega-3 fatty acids [ 4 , 5 , 6 , 7 ]. Compared to canola oil, soybean oil possesses a different fatty acid profile with high amounts of linoleic acid (53–56%), followed by oleic acid (17–20%) and linolenic acid (12–15%).…”

“…Compared to canola oil, soybean oil possesses a different fatty acid profile with high amounts of linoleic acid (53–56%), followed by oleic acid (17–20%) and linolenic acid (12–15%). Both also contain saturated fatty acids with 3–5% and 9–12% of palmitic acid (C16:0) in canola and soybean oils, respectively [ 4 , 5 , 6 , 7 ]. High unsaturated fatty acids and relatively low saturated fatty acid contents in both oils are associated with ranges of health benefits: decrease of LDL cholesterols, increase of HDL cholesterols, increase of insulin resistance, and prevention of cardiovascular diseases, heart disease, and cancer [ 8 ].…”

“…In general, heat treatment opens up the double bonds of unsaturated fatty acids and therefore, the higher the number of double bonds in the fatty acid chain, the greater the chance of being oxidized during frying. That is, polyunsaturated fatty acids undergo lipid oxidation more easily than monounsaturated fatty acids during frying and thereby soybean oil with a relatively higher proportion of polyunsaturated fatty acids is anticipated to be more prone to lipid oxidation than canola oil [ 4 , 5 , 6 , 7 ].…”

Can the Image Processing Technique Be Potentially Used to Evaluate Quality of Frying Oil?

“…Presently, some methods such as Fourier transform infrared (FTIR) [18,19], nuclear magnetic resonance (NMR) [20], low-field nuclear magnetic resonance (LF-NMR) [21], fluorescence spectroscopy [22], and gas/liquid chromatography [23] have been developed as alternative techniques to measure the quality of frying oils. ese methods are very accurate and require low quantities of hazardous solvents, but the equipment is very expensive.…”