Total Polar Compounds Content Research Articles

The influence of high oleic oils during intermittent frying on the formation of acrylamide in french fries

High oleic oils are often used for industrial frying considering a better nutritional value and stability to thermal oxidation than high polyunsaturated fatty acid oils. This research aimed to investigate the correlation between total polar compound (TPC) and acrylamide content during intermittent frying using high oleic oils such as super palm olein (SPO), high-oleic canola oil (HOCO) and high-oleic sunflower oil (HOSO). All oils were accessed in terms of fatty acid composition and tocopherol quantity prior to intermittent frying. The TPC of frying oil was recorded at every 8th interval of the frying cycle and french fries fried with respective oils were collected, and oil was extracted for acrylamide quantification using HPLC-MS. Pearson correlation showed a positive correlation between the total polar compound of frying oil and the acrylamide content of french fries (p<0.01). SPO contained the highest total tocopherol content, followed by HOCO and HOSO, accordingly. French fries fried with SPO had the lowest acrylamide content, followed by HOCO and HOSO, respectively. By contrast, SPO had the highest TPC content throughout the frying cycles, followed by HOCO and HOSO. The presence of oleic acids might not produce higher TPC, however, it produced higher acrylamide formation in the french fries. Overall, SPO is suitable for intermittent frying uses as it yielded the lowest concentration of acrylamide in french fries.

Impact of red wine polyphenol carbon dots on the oxidative stability of oils

Red wine polyphenols carbon dots (P-CDs) with antioxidant properties were synthesized and extensively characterized to determine their size, morphology, and microstructure. Their potential to enhance oxidative stability in sunflower oil was thoroughly evaluated and compared with traditional antioxidants like butyl hydroxyanisole (BHA) and n-propyl gallate (PG). The P-CDs were found to be spherical nanoparticles, generally smaller than 10 nm, confirming their nanoscale characteristics. Further analysis revealed that the unique properties of the P-CDs were largely due to oxygen-containing functional groups and a highly defective graphite structure, providing them with distinct physical and chemical attributes. In scavenging tests with DPPH and ABTS radicals, P-CDs demonstrated outstanding performance, suggesting their promising application in the antioxidant field. Additionally, the P-CDs effectively inhibited the oxidative rancidity process in sunflower oil, offering a novel approach to improving oil's oxidative stability. A significant finding was that when 0.01% of red wine polyphenol carbon dots were added, they outperformed both BHA and PG in inhibiting the accumulation of anisidine, reducing total polar compound content, and preserving the oil's fatty acid composition, color, and viscosity. This discovery not only broadens the application scope for P-CDs in antioxidant research related to oils, but also supports their practical implementation in the food industry.

A Novel Model for Evaluating the Natural Antioxidant Carnosic Acid to Improve the Stability of Rapeseed Oil in the Thermal Degradation.

The quality and stability of oil during thermal processing reflect the reactions in vegetable oil. The deterioration of the oil is close to the viscosity, fatty acid composition (FA), total polar compounds (TPC), etc. Carnosic acid (CA) is the main antioxidant component of rosemary extract; it is a natural and clean-label antioxidant that is allowed to be added to prolong oil processing and storage. To achieve a clear correlation of this situation, a novel stability evaluation model was used to predict the thermal degradation of rapeseed oil (RSO) with CA. The RSO with CA (200 mg/kg, 400 mg/kg, and 700 mg/kg), the tert-Butylhydroquinone (TBHQ, 200 mg/kg), and the fresh RSO (without additives) during thermal processing (180 ± 5 °C) were studied. The temperature dependency of viscosity fits well with the Lioumbas model (R2 ≥ 0.999). The parameter b value in the Lioumbas model showed a decrease linearly with the processing time (tP, R2 ≥ 0.965). The multiple linear regression analysis showed that the accuracy of the model in predicting viscosity was less than ±2 mPa·s-1, and the deviation% was less than ±10% in all the samples. After 32 h of thermal degradation, the addition of 700 mg/kg CA showed the lowest degradation rate (13.84%) of polyunsaturated fatty acids (PUFAs), and the TPC content was 26.00 ± 0.50%. The TPC showed a positive relationship with viscosity (r = 0.99, p < 0.01), tP (r = 0.97, p < 0.01), and effective carbon numbers (ECN, r = 0.84, p < 0.05). In conclusion, this study can make a potential prediction for the stability of RSO.

Study by means of 1H nuclear magnetic resonance of the oxidation process in high oleic sunflower oil and palm oil during deep-frying of fish cakes

This study aimed to compare the frying performance of palm oil (PO) and high oleic sunflower oil (HOSO) during frying aquatic products. The quality change and frying performance of HOSO and PO during frying of fish cakes were investigated. The oxidation and hydrolysis products of both oils were explored by the nuclear magnetic resonance technique. The results showed that the color deepening rate of PO was higher than that of HOSO. After 18 h of frying, the total polar compound content of PO and HOSO reached 25.67% and 27.50%, respectively. HOSO had lower degree of oxidation than PO after 24 h of continuous frying. The polyunsaturated fatty acid content in HOSO and PO significantly decreased. The oleic acid content in HOSO remained above 80% during the frying process. The major aldehydes in both oils were (E, E)-2,4-alkadienals and n-alkanals and glycerol diesters (DAGs) were abundant in PO. Furthermore, the addition of fish cakes had slight effect on the quality of the frying oil. Therefore, HOSO is an appropriate candidate for frying owing to its excellent frying stability and nutritional value.

Lipid concomitant γ-oryzanol decreased oil absorbency of French fries by changing the microstructure of French fries and physical properties of frying oil.

The aim of this research was to evaluate the possibility of lipid concomitant γ-oryzanol reducing oil absorbency of fried foods and the underlying mechanism. Therefore, the influence of γ-oryzanol on moisture and oil content, and distribution and micromorphology of French fries and the viscosity, fatty acid composition and total polar compounds content of rice bran oil (RBO) after frying were studied. Our results showed that the incorporation of low concentration of γ-oryzanol [low addition group (LAG)] (5.754 g/kg) decreased the oil absorbency and porous structure of French fries during frying. Additionally, LAG incorporation inhibited the degradation of linoleic acid, decreased the growth rate of saturated fatty acids, total polar compounds and viscosity of frying oil. Consequently, it was recommended to incorporate a small amount of γ-oryzanol in frying oil because it could inhibit oil absorption behavior of French fries. © 2023 Society of Chemical Industry.

Effect of Heating Temperature of High-Quality Arbequina, Picual, Manzanilla and Cornicabra Olive Oils on Changes in Nutritional Indices of Lipid, Tocopherol Content and Triacylglycerol Polymerization Process.

The aim of the study was to determine the stability and heat resistance of extra premium olive oil. The study material consisted of six extra virgin olive oils (EVOO) obtained from Spain. Four samples were single-strain olive oils: Arbequina, Picual, Manzanilla, and Cornicabra. Two samples were a coupage of Arbequina and Picual varieties: Armonia (70% Arbequina and 30% Picual) and Sensation (70% Picual and 30% Arbequina). Olive oil samples were heated at 170 °C and 200 °C in a pan (thin layer model). In all samples, changes in indexes of lipid nutritional quality (PUFA/SFA, index of atherogenicity, index of thrombogenicity, and hypocholesterolemic/hypercholesterolemic ratio), changes in tocopherol, total polar compounds content, and triacylglycerol polymers were determined. Heating olive oil in a thin layer led to its degradation and depended on the temperature and the type of olive oil. Increasing the temperature from 170 to 200 °C resulted in significantly higher degradation of olive oil. At 200 °C, deterioration of lipid nutritional indices, total tocopherol degradation, and formation of triacylglycerol polymers were observed. A twofold increase in the polar fraction was also observed compared to samples heated at 170 °C. The most stable olive oils were Cornicabra and Picual.

A Comparison of the Stability of Refined Edible Vegetable Oils under Frying Conditions: Multivariate Fingerprinting Approach.

The stability of highly consumed vegetable refined oils after discontinuous frying of potatoes was compared. Both those vegetable oils containing additives and those that did not were considered. Vegetable oil samples were evaluated using refractive index, anisidine and peroxide values, UV absorbance and dielectric constant-based determination of the content of total polar compounds. Chemical changes caused over the frying time were monitored and multivariate modelling of the data was carried out. A new gas chromatographic-mass spectroscopy method was intended to record a fingerprint of both polar and non-polar compound fractions. Multivariate models of chromatographic fingerprints were also developed, and the results obtained from both approaches were verified to be statistically similar. In addition, multivariate modelling also allows to differentiate among vegetable oils according to oxidation performance. Indeed, it was initially observed that olive oils presented the highest natural thermo-oxidative stability compared to other seed oils, although it should be noted that these differences were not significant when regarding olive pomace oils and seed oils containing synthetic additives.

Monitoring the oxidation process of soybean oil during deep-frying of fish cakes with 1H nuclear magnetic resonance

The oxidation process of soybean oil (SBO) during frying fish cakes was investigated. The TOTOX value of before frying (BF) and after frying (AF) was significantly higher than control (CK). However, the total polar compound (TPC) content of AF reached 27.67% in frying oil continuously frying at 180℃ for 18 h, and 26.17% for CK. 2,2-Diphenyl-1-picrylhydrazyl (DPPH) loss in isooctane and methanol significantly decreased with the extension of frying time and then tended to be stable. The decrease of DPPH loss was related to the increase of TPC content. Antioxidant and prooxidant balance (APB) value below 0.5 was obtained after 12 h for heated oil. (E)-2-alkenals, (E, E)-2,4-alkadienals, and n-alkanals were dominant ingredients among the secondary oxidation products. Traces of monoglycerides (MAG) and diglycerides (DAG) were also detected. These results may improve our understanding of the oxidation deterioration in SBO during frying.

Validity of total polar compound and its three components in monitoring the evolution of epoxy fatty acids in frying oil: Fast food restaurant conditions

This study evaluated the validity of total polar compounds (TPC) and its three components in monitoring the evolution of epoxy fatty acids in frying oil under fast food restaurant conditions. The content of epoxy fatty acids can be predicted using the TPC rather than oxidized triglyceride monomer. When TPC content reached 24 g/100 g, 25 g/100 g, and 27 g/100 g, the epoxy fatty acid content in oil was found to be 1.47–3.63 mg/g, 1.58–4.06 mg/g, and 1.83–5.08 mg/g, respectively. More epoxy fatty acids were generated in high oleic sunflower oil than in canola and cottonseed oil during frying. At current discarding points of TPC 24–27 g/100 g, its epoxy fatty acid content was 3.63–5.08 mg/g, which was lower than the limit of 7 mg/g recommended by Max Rubner-Institut in Germany. Our results indicate that the risk of epoxy fatty acids can be monitored using the current TPC index.

Systematic comparison on the deep-frying performance of different vegetable oils from literature data using the rate of parameter change approach

Direct comparison of the frying performance of vegetable oils based on the data reported in literature is difficult because of the inconsistent experimental protocols used in different studies. This research aimed to develop a method, known as ‘Rate of Parameter Change’ (RPC) to evaluate the deep-frying results obtained from literature data. A literature search was conducted using PubMed, Web of Science and Scopus to identify the studies that reported the deep-frying results using different types of vegetable oils (palm olein, canola oil, soybean oil, sunflower oil). A total number of 32 studies were selected in this work based on the pre-defined selection criteria. The quality parameters examined were polyunsaturated fatty acid composition (PUFA), free fatty acid content (FFA), total polar compound content (TPC), anisidine value (AV) and di- and polymerized triacylglycerol content (DPTG). The data extracted from each study were normalized with the number of frying cycles reported in the study. The normalized values for a parameter examined were reported as RPC. The RPC computed from different studies were then compared and evaluated using a box plot. This method had revealed a distinct trend, where the PO was found to have a higher stability against thermo-oxidative alterations compared to the soft oils (CNL, SBO, SFO) during deep-frying application. However, some of the calculated RPC values have large standard deviations which are attributed to the inconsistent experimental protocols used in different studies. This observation calls for a standardized protocol in deep-frying experiments to facilitate the comparison of quality parameters between different studies and between different types of vegetable oils.

Influence of Prolonged Deep‐Frying Using Various Oils on Volatile Compounds Formation of French Fries Using GC–MS, GC‐O, and Sensory Evaluation

AbstractFlavor is a decisive sensory characteristic to determine the popularity of French fries (FF). To investigate the effect of prolonged deep‐frying using various oils on volatiles formation of FF, the FF were prepared in the palm oil (PO), soybean oil (SO), and high‐oleic rapeseed oil (RO) for 24 hours intermittent frying. The effect of oil types was found to be more significant than the frying time on the volatiles of FF indicated from the clusters of the fried FF by chemometric analysis. A total of 26 key aroma‐active compounds were identified by aroma extract dilution analysis, in which aldehydes were predominant. The FF fried in SO revealed higher desirable aroma compounds, i.e., (E, E)‐2,4‐decadienal and it increased to maximum value at 12 hours, and left the deep‐fried odor in FF. Meanwhile, a significant increase in metallic off‐flavor was observed in FF fried in SO and PO at 20 hours, indicating that oil quality reduction resulted in FF with unappealing flavor. The above results showed that frying process had an optimum frying window (approximately 4–16 hours with total polar compounds content below 22.2%), and the French fries prepared in this period obtained higher flavor scores. The study will provide insights into the effect of oil types and oxidation degree on obtaining the ideal flavors for fried food.

Comparative analysis of the effects of novel electric field frying and conventional frying on the quality of frying oil and oil absorption of fried shrimps

Production of high-quality fried foods with low oil content receives considerable attention from consumers and producers. The effects of electric field frying (EFF) and conventional frying (CF) on the physicochemical properties of frying oil, the oil absorption behavior, and the microstructural changes in fried shrimps were compared and evaluated in this study. Results showed the application of EFF could delay the degradation of frying oil evidently compared with CF. The increasing rate of total polar compound content, acid values, viscosity, and color deepening of EFF oil was slower (p < 0.05) than that of CF oil during the prolonged frying. The analysis of the results of low field nuclear magnetic resonance (LF-NMR) measurements confirmed our findings. In addition, the fried shrimps produced by EFF had reduced oil content (p < 0.05), increased water retention (p < 0.05), even oil distribution, and decreased microstructure damage via the observation of magnetic resonance imaging, confocal laser scanning microscope (CLSM), and scanning electron microscope. Results may provide ideas for producing high-quality fried products with low oil content and delaying oil degradation during frying.

Effects of carbon dots in combination with rosemary-inspired carnosic acid on oxidative stability of deep frying oils

Antioxidative carbon dots (CDs) were prepared and first characterized in terms of their morphology, size and microstructure. The feasibility of CDs to enhance oxidative stability of a blend soybean and palm frying oil was then evaluated; the efficacy of CDs was evaluated in comparison with those of rosemary-inspired carnosic acid (CA), combined CA/CDs and tert-butylhydroquinone (TBHQ). CDs appeared as spherical nanoparticles with the size smaller in general than 1 nm. Their characteristic features could be attributed to their oxygen functional groups and highly defected graphitic structure. CDs exhibited superior properties for scavenging DPPH, hydroxyl and superoxide anion radicals. Both CA and CDs showed significant inhibitory effect against oxidative rancidity of the oil. Interestingly, 0.05% CA/CDs displayed similar inhibitory effect as 0.02% TBHQ in terms of p-anisidine value, total polar compounds content, fatty acids composition, conjugated diene and triene contents as well as color and viscosity of the oil.

Influence of Oil Types and Prolonged Frying Time on the Volatile Compounds and Sensory Properties of French Fries.

In order to study the flavor of French fries (FFs) prepared in different frying oils, we identified and compared the volatiles of FFs fried in high-oleic sunflower oil (HSO), sunflower oil (SO), linseed oil (LO), and palm oil (PO) during prolonged 24 h frying time. 47 different kinds of volatiles were presented, and aldehydes were the most abundant compounds. The FFs prepared in SO were rich in alkadienals, especially the (E, E)-2,4-decadienal, thus inducing the highest deep-fried odor. The content of alkenals was higher in FFs prepared in HSO, among which (E)-2-nonenal and 2-undecenal provided the undesirable oily flavor. Whereas, FFs prepared in PO were rich in alkanals, and showed an undesirable green aroma because of hexanal. Besides, the aldehydes in FFs fried in LO were the least with more undesirable flavor substances (e.g. (E, E)-2,4-heptadienal). In addition, except for the FFs fried in LO, the aldehydes in other FFs showed an increasing trend. While, the volatiles from the Maillard reaction (e.g. pyrazines) showed no clear pattern. Meanwhile, frying process had optimum frying window (approximately 12 h with total polar compounds content of 14.5%-22.2% in different oils), and the French fries prepared in this period obtained higher flavor score. Therefore, the comparison related to volatiles of FFs provided a basis for the flavor control to a certain extent.

Use of ethanol extract of Chuanminshen Violaceum to inhibit the deterioration of frying oil

Influence of ethanol extract of Chuanminshen Violaceum (EEC) on the changes in physicochemical characteristics of soybean, rapeseed, and palm oils during frying was investigated. Composition analysis revealed that a total of 16 compounds with possible antioxidant activity were contained in the obtained EEC, such as bergaptol, curcumenol, viscutin, homobutein, nissolicarpin, and 4-hydroxyisopimpinellin. Similar to tert-butylhydroquinone (TBHQ), EEC inhibited the increases in acid value, carbonyl value, and total polar compound content of frying oil during frying. The decrease in content of polyunsaturated fatty acids and the increase in content of saturated fatty acids were also significantly inhibited in TBHQ-added or EEC-added oils. More than 45 % of the reduction in concentration of octanoic acid was obtained in EEC-added oils, which was comparable to those observed in TBHQ-added oils. Thermal oxidative degradation of polyunsaturated fatty acids was proven to be retarded by adding EEC and TBHQ to moderate the deterioration of frying oil. Thus, the potential use of EEC as a natural antioxidant was demonstrated to extend the usage life of vegetable oils with a high content of polyunsaturated fatty acids during frying.

Total Polar Compounds and Acid Values of Repeatedly Used Frying Oils Measured by Standard and Rapid Methods

Soybean oil and palm olein were used to fry French fries, chicken leg fillets and pork chops. Total polar compounds were measured by column chromatography and two rapid-measuring devices (Ebro FOM 310 and Testo 270). Acid value was determined by titration method and a 3M Shortening Monitor. The results showed that the content of total polar compounds and acid value in both soybean oil and palm olein increased linearly with frying time. The influence of oil type on the content of total polar compounds and acid value in used oil was significant, but the effect of food type on these parameters was not observed. The rate of total polar compounds generation in palm olein was lower than that in soybean oil. All rapid methods used in this study had results that highly correlated with those from column chromatography, but moderately correlated with the titration method. We found that Ebro FOM 310 was more suitable for monitoring the quality of soybean oil during frying, while Testo 270 was suitable for palm olein. These results provided the basis for choosing the proper rapid-measuring device to control the quality of frying oil in restaurants.

Near-infrared prediction of edible oil frying times based on Bayesian Ridge Regression

In the detection and analysis of edible oil quality, Total Polar Compound (TPC) has been widely used as an evaluation index of frying oil quality. Its content has been shown to have a linear relationship with the number of frying times. The more frying times, the higher the TPC content in the oil, the worse the quality of the oil. In this study, a Bayesian Ridge Regression (BRR) model is established to detect the frying times of soybean oil, peanut oil, and rapeseed oil based on near-infrared spectroscopy (NIRS) detection techniques. The study collects a total of 450 spectral signals from soybean oil, peanut oil and rapeseed oil. Then partial least regression (PLS), Support Vector Regression (SVR) and BRR prediction models are established to predict frying times of the three frying oils and furthermore to reflect the quality of frying oils. The results show that under the full spectra, the SVR and BBR prediction regression models established by the original spectra and the standard normalized variable (SNV) processed spectra can predict the frying times better, while the PLSR model cannot effectively predict the frying times in all cases. After selecting the characteristic wavelength through UFS, the BRR prediction model works best. The coefficient of determination (R2) and the root mean square error of prediction (RMSEP) of the model are 0.9852, 0.5463, respectively. In summary, the method of this study can effectively predict the number of frying times and provide an effective means for the rapid detection of frying oil quality.

Quality assessment of frying oil using short-chain fatty acid profile and infrared spectrum coupled with partial least squares

The deterioration of soybean oil (SO), palm oil (PO), and rapeseed oil (RO) for deep-fat frying chicken breast meat (CBM) and potato chips (PCs) was evaluated based upon their short-chain fatty acids (SCFAs) profiles as well as free fatty acid (FFA) content, carbonyl value (CV), and total polar compounds (TPC) content. In addition, Fourier-transform infrared (FTIR) spectra of oils combined with partial least squares were applied to predict the FFA content, CV, and TPC content in oils. Results showed that the formation of SCFAs was accompanied the reduction of unsaturated fatty acids during 12 h/day for 3 days. For frying PCs with SO, the heptanoic acid (C7:0) continuously increased from 0.01 to 0.15 g/kg and octanoic acid (C8:0) increased from 0.008 to 0.65 g/kg, while the contents of linoleic and linolenic acids reduced from 45.69–41.43 to 4.03–3.20%, respectively. For frying CBM with RO, the contents of C7:0, C8:0, and nonanoic acid were in ranges of 0.05–0.38, 0.03–1.19, and 0.11–0.17 g/kg, while contents of linoleic and linolenic acids reduced from 22.15–18.89 to 7.83–6.21%, respectively. The FFA content, CV, and TPC content in oils predicted by the constructed linear regression model were in ranges of 0.21–2.61 KOH g/kg, 9.76–58.98 meq/kg, and 8.02–36.91%, respectively. The root mean standard error of prediction, coefficient of determination (R2) for the validation set, and ratio of prediction to deviation for all validation analyses were in ranges of 0.2127–6.7364, 0.8717–0.9608, and 1.1548–4.2984, respectively. A logistically positive relationship (R2 = 0.7982-0.9700) between the content of C8:0 and CV or TPC content was found in frying oils used for frying both CBM and PCs. Thus, both the measurement of SCFAs and FTIR analysis could be used to efficiently monitor the deterioration of frying oils during deep-fat frying.

Rapid Determination of Total Polar Compounds in Frying Oil Using ATR‐FTIR Combined with Extended Partial Least Squares Regression

AbstractA method of rapidly determining the total polar compounds (TPCs) in frying oils using attenuated total reflectance‐Fourier transform infrared spectroscopy combined with partial least squares (PLS) regression is developed. Oils of various types and geographic origins are used to ensure that the proposed model is robust. The first derivative spectrum is selected as the spectral processing method. The interval PLS, forward interval PLS, and backward interval PLS algorithms are compared in terms of their performance. A correlation coefficient (R2) of 0.9942, a root mean square error of calibration (RMSEC) of 1.1, a root mean square error of prediction (RMSEP) of 2.30, a residual predictive deviation (RPD) of 4.1, and a limit of detection (LOD) of 1.65% are obtained by the fiPLS33 model with fewer latent variables and a lower spectral interval number. In addition, sub‐models using a single type of oil showed higher performance (R2 0.9957–0.9998, RMSEC 0.12–0.92, RMSEP 0.79–1.58, RPD 4.79–9.64, LOD 0.66–1.26%) than the general model. The TPC models developed are accurate, stable, and adaptable, and they can be used to analyze general frying oil samples quickly, regardless of the oil type, and to analyze samples of specific oil types accurately.Practical applications: The content of TPCs is an important indicator of whether the oil has been overused and whether it will be harmful during the frying process. However, traditional chemical methods are time‐consuming, and they have not been used to determine large‐sized samples. In addition, due to a lack of regional optimization, most studies on determining TPCs with FTIR give unsatisfactory model performance. A general TPC model that incorporates several oil types and regional optimization is expected to improve prediction performance. Therefore, the proposed method represents a rapid and accurate tool for measuring TPCs in edible fats and oils.

Physiochemical properties of short-term frying oil for chicken wing and its oxidative stability in an oil-in-water emulsion.

In this study, the physiochemical properties of corn oil and its oxidative stability in an O/W emulsion were studied following short‐term (120 min) deep‐frying of chicken wing. The results showed that the levels of polyunsaturated fatty acids in corn oil decreased after frying. Furthermore, total polar compound content in frying oil was significantly increased to 11.3%. Fourier transform infrared spectra (FTIR) indicated that hydrolysis and oxidation reactions involving triglycerides occurred after frying. Additionally, the increased a* and b* values demonstrated that deep‐frying greatly enhanced the intensity of the red and yellow colors of corn oil. Frying reduced the oxidative stability of corn oil in an O/W emulsion as determined by the peroxide value and acid value. These findings indicated that short‐term deep‐frying of chicken wing deteriorated the quality of corn oil and decreased its oxidative stability in an O/W emulsion. Consumers should consider the potential hazards of food containing short‐term deep‐frying oil.