Thermal Decomposition of Partially Hydrogenated Rapeseed Oil During Repeated Frying Traditional and Fast French Fries

Abstract

The aim of this study was to compare thermal degradation of oil, especially the composition of the polymer in a polar and nonpolar fraction of oil, used for repeated frying of fast and traditional French fries. The French fries were fried using the partially hydrogenated rapeseed oil. Fast French fries were characterized by a half shorter frying time compared to traditional ones. The frying process was done at 170 C AE 5 C in 5-l electric fryers and carried out in 15-min cycles for 48 hours. The content of thermal decomposition of triacylglycerol (TAG) in both fractions of oil was analyzed by high-performance sizeexclusion chromatography (HPSEC). In all analyzed samples, thermal decomposition products were found. However, the composition of a polar and nonpolar fraction of oil was not the same. In a nonpolar fraction, only the monomers and hydrolysis products of TAG were observed. In a polar fraction, dimers, trimers, and oligomers of TAG were also found. The shorter time of frying the fast French fries resulted in a lower total and individual polymers content in all steps of analysis compared to the oil used for frying the traditional French fries.Keywords Thermal decomposition of oil Á Polymerization of frying oil Á Rapeseed oil Á Triglyceride polymers Á Repeated frying Á Size-exclusion chromatography J Am Oil Chem Soc (2018) 95: 473-483. Fatty Acid Composition AnalysisFatty acid composition was determined according to American Oil Chemists' Society (AOCS) Official Method Ce 474 J Am Oil Chem Soc J Am Oil Chem Soc (2018) 95: 473-483 AE 2.87e 100.79 AE 3.26d 49.27 AE 2.58g 12.64 AE 2.58de 1.94 AE 1.61ab nd 50.03 AE 16.29b 751.60 AE 19.98f nd 40 5.12 AE 2.02bcde 38.76 AE 4.05g 104.26 AE 8.65de 57.39 AE 3.51h 13.46 AE 3.51ef 3.67 AE 1.41bc 6.76 AE 6.63a 53.20 AE 24.30b 717.38 AE 33.71de nd 48 5.46 AE 4.24bcde 50.97 AE 0.86i 115.83 AE 4.24e 55.67 AE 1.61h 13.90 AE 1.61ef 8.17 AE 4.08d 8.90 AE 9.00a 51.42 AE 1.37b 689.68 AE 11.36cd nd Values are means of six determinations AE SD. Means in the same column followed by different small letters indicate significant differences (P < 0.05). nd, not detected. 1 In all samples of nonpolar fraction, trimers and oligomers were not detected. 478 J Am Oil Chem Soc J Am Oil Chem Soc (2018) 95: 473-483

Effect of Deep Frying of Potatoes and Tofu on Thermo-Oxidative Changes of Cold Pressed Rapeseed Oil, Cold Pressed High Oleic Rapeseed Oil and Palm Olein

“…The study of sunflower and high oleic sunflower oils also reported a significant increase of TPC: from 1.76% to 15.93% after 24 h of deep frying at 180 • C [49]. In addition, Kmiecik et al [50] reported that the final level of TPC in partially hydrogenated rapeseed oil used for frying the traditional and fast French fries was 6.3 and 5.3 time higher compared to fresh oil, respectively. The limit of TPC in oils differs depending on the country, e.g., Poland, Italy, Spain, France, and India have set a limit of 25%, Germany, of 24%, while Austria, Netherlands, Australia, China, and Switzerland have set it at 27% [35].…”

Polar compound composition of four vegetable oils as affected by tert‐butylhydroquinone (TBHQ) and chlorophyll during room‐temperature storage

“…PCA is one of the fundamental methods of chemometrics, and it was used for dimensionality reduction and for identification of the relationships between the variables and samples (Xu et al ., 2016). This method has been efficiently used in the study of polar compound composition of edible oils (Kmiecik et al ., 2017; Kmiecik et al ., 2018). Figure 1a demonstrates the PCA scatter plot that shows the classification among four types of vegetable oil samples on the basis of variations of polar compound composition induced by different treatments.…”

“…Compared with hydrolysed compounds, the resorption rate of OxTGs, TGDs and TGOs is high enough to induce toxic effects on animals (Li et al ., 2016). Moreover, TAG oligopolymers (TGPs, TGO + TGD) are important indicators related to the quality evaluation of edible oil and include a large complex group with the –C–C–, –C–O–C– and –C–O–O–C– linkages in their structure (Kmiecik et al ., 2018). The maximum TGP limit between 10% and 16% has been suggested in official legislations from different countries (Ahmad Tarmizi et al ., 2019).…”

Degradation of Tocopherol Molecules and Its Impact on the Polymerization of Triacylglycerols during Heat Treatment of Oil

“…An oil sample was fractionated into the polar and non-polar fractions using silica gel, according to Kmiecik et al [47]. Briefly, the oil was dissolved in toluene and applied to a silica gel column.…”

“…An oil sample was fractionated into the polar and non to Kmiecik et al [47]. Briefly, the oil was dissolved in tolue non-polar fraction was eluted with a mixture of hexane an fraction was eluted with pure diisopropyl ether.…”