Frying Oil Quality Research Articles

Enhancing the quality of fried sunflower oil by oak hull ash as an efficient adsorbent

Enhancing the quality of fried sunflower oil by oak hull ash as an efficient adsorbent

Retarding sunflower oil oxidation during the deep-fat frying of potato chips using micro-encapsulated Convolvulus arvensis Linn leaf phenolic extract

In this research, the extraction of polyphenols from Convolvulus arvensis (CA) leaves was optimized using ethanol (80%) at plant/solvent ratios and extraction times which varied between 1/10 to 1/30 (w/v) and 20 to 120 min, respectively. The extract with the highest polyphenol content was obtained at a ratio of 1/30 and 90 min. At 120 ppm, the preceding extract in either lyophilized (LyCAE) or encapsulated (EnCAE) form was evaluated as an antioxidant during the frying process using sunflower oil in comparison to TBHQ. Frying oil quality indices including refractive index, smoke point, acid value, anisidine value, polar and polymer compounds were monitored throughout frying times. FTIR spectroscopy was used to investigate the changes in trans-fatty acids, hydroperoxides and aldehyde contents. The results showed that the phenolic extract, especially in EnCAE form, exhibited superior antioxidant activity over TBHQ, which consequently led to the utilization of this phenolic extract as an antioxidant in frying oils.

Rapid assessment of degraded frying oil quality using interdigitated microelectrode capacitive sensors

AbstractFrying oil is essential in food processing, influencing both the taste and safety of fried foods. However, its quality can deteriorate with repeated use, posing potential risks. Many current methods for evaluating its quality, such as spectroscopic techniques, are time‐consuming and costly. Our study introduces an affordable and rapid device that uses electrical capacitance to assess the quality of frying oil. We developed a capacitive sensor equipped with interdigitated microelectrodes (IEMs) to measure the oil's dielectric constant. After calibrating the sensor's features, we achieved highly precise results. Our design utilized Corel software for drafting and CNC machinery for precise sensor fabrication. In air, the sensor's measurements closely aligned with theoretical predictions, registering an R2 value above 0.7. We identified a correlation between frying frequency and significant shifts in the dielectric constant across three oil samples. Using a signal circuit to adjust the oscillation frequency and a microprocessor for data interpretation, we classified oils into three safety categories: safe, moderate, and risky. Our device provides a cost‐effective and user‐friendly solution to assess frying oil quality, proactively addressing health concerns arising from oil degradation.Practical Applications: Our capacitive sensor device can be widely applied in the food industry and restaurants, ensuring the safety and quality of fried products. By using this device, manufacturers and kitchens can make informed decisions about reusing frying oil or replacing it as needed, reducing wasted oil. This cost‐saving device also has the potential to contribute to improving food safety issues.

Effects of amino acids on the formation and distribution of glycerol core aldehydes during deep frying

Glyceryl core aldehyde (GCAs) are hazard factors produced during the frying process using oils and fats, and GCAs control and mitigation research is very important. This study investigated the effects of adding amino acids (methionine, glycine, and histidine) at 2.5, 5, and 10 mM on the formation and distribution of four GCAs during frying. High oleic sunflower oil (HOSO) was selected as frying oil for French fries. After 12 h of frying, the content of GCAs in the tert-butylhydroquinone-treated group (0.02 wt%, 1.1 mM) decreased by 29 % compared with the control group. The addition of methionine, glycine, and histidine decreased the total GCAs by 51 %, 28 %, and 27 %, respectively. The total GCAs content was best inhibited by methionine, while glycine and histidine were not significantly different from TBHQ. Methionine addition significantly reduced GCAs (9-oxo), GCAs (10-oxo-8), and GCAs (11-oxo-9) by 39 %, 78 %, and 80 %, respectively, while histidine was the most potent inhibitor of GCAs (8-oxo), which decreased by 40 %. Methionine also proved effective in slowing degradation of frying oil quality. These results provide a new direction for decreasing GCAs in frying systems.

Development of a sensor-based fluorescent method for quality evaluation of used frying oils

The sensor-based fluorescent spectroscopy was developed for the rapid evaluation of oil quality at different frying stages. Manganese tetraphenylporphyrin was selected as the fluorescent sensor according to its sensitivity and selectivity to the oxidation products in frying oil. The performance of the selected fluorescent sensor was calculated based on density functional theory. The fluorescent sensor was then made to detect frying oil quality every 24 h within eighteen days. A fluorescence profile for each oil sample was obtained from the fluorescent sensor reacting with the oil sample. The feature data of fluorescence spectra were extracted using the parallel factor analysis algorithm. All oil samples were classified into three oxidation groups using principal component analysis and support vector machine algorithms. Finally, the classification algorithm of the support vector machine coupled with the genetic algorithm achieved the best classification accuracy of 96.67% and 93.33% in the training set and test set, respectively. The overall results demonstrated that this fluorescent sensor could successfully be applied in the discrimination of frying oil with different oxidation states.

Effect of frying oil stability over repeated reuse cycles on the quality and safety of deep-fried Nile tilapia fish (Oreochromis niloticus): a response surface modeling approach

ABSTRACT Fresh water fish is considered a source of good quality proteins and essential fats. Frying is among widely used fish preparation techniques globally. Deep-frying oil quality with repeated uses, has been a concern. This research investigated the influence of frying oil stability (expressed as levels of peroxide values (0.2, 1.2 meq/kg) and free fatty acids (0.05, 0.13% palmitic acid)) over repeated uses (1,6 cycles) on the oxidative stability and essential nutrients of fried fish using a response surface approach, with the objectives of generating information relevant for the improvement of community health outcomes, with a special focus of this particular research was on trends, but not optimization. The frying oil and fried fish quality were adequately explained by response surface model and supported by principal component analysis. The result showed that the oxidative stability of both the frying oil and fried fish were deteriorating over the reuse cycles of the frying oil (with increasing trends of unhealthy fats, saturated and trans) corresponding to decreasing trends in the healthy fat components and vitamin A). It was also indicated that the essential fats (omega 3, omega 6, cis, vitamin A), were decreased while the risky fats (saturated, trans) were increased along with the frying cycles. The result revealed the urgent need for regulating frying oil and fried food qualities, particularly in developing countries.

Frying edible vegetable oil quality from street-food vendors in a Metropolitan area in the Central Highlands of Mexico

Vegetable oil deterioration during frying is a health problem because of oil degradation compounds and recycled oil practices are related to disturb oil quality. Frying food street-vendors are an important part of endemic market type Tianguis at the Metropolitan areas in the Central Highlands of Mexico. The main objective of this research was to evaluate frying edible vegetable oil quality from frying by street-food vendors in a Metropolitan area in the Central Highlands of Mexico. A behaviour questionary registered fresh and recycling oil addition, frying temperature and method in real operation conditions for three working days. Free fatty acid, colour, p-Anisidine, peroxide, and TOTOX indexes were observed in the vendors by triplicate. Free fatty acids and peroxide values in two vendors exceeded the NMX-F-223-SCFI-2011 values. Physicochemical variables revealed oil oxidation deterioration. Not so high temperatures were registered, and continually fresh oil addition was suggested as mitigating or masking edible oil of thermal oxidation and its degradation agents during the observed time. Thermal oxidation could be lower than in controlled conditions as in many reports due to vendor operations studied as a real approximation that suggested less oil degradation. Present results could be evidence for government intervention in the regulation needs.

Rapid quantification of acid value in frying oil using iron tetraphenylporphyrin fluorescent sensor coupled with density functional theory and multivariate analysis

Abstract A metalloporphyrin-based fluorescent sensor was developed to determine the acid value in frying oil. The electronic and structural performances of iron tetraphenylporphyrin (FeTPP) were theoretically investigated using time-dependent density functional theory and density functional theory at the B3LYP/LANL2DZ level. The quantified FeTPP-based fluorescent sensor results revealed its excellent performance in discriminating different analytes. In the present work, the acid value of palm olein was determined after every single frying cycle. A total of 10 frying cycles were conducted each day for 10 consecutive days. The FeTPP-based fluorescent sensor was used to quantify the acid value, and the results were compared with the chemical data obtained by conventional titration method. The synchronous fluorescence spectrum for each sample was recorded. Parallel factor analysis was used to decompose the three-dimensional spectrum data. Then, the support vector regression (SVR), partial least squares, and back-propagation artificial neural network methods were applied to build the regression models. After the comparison of the constructed models, the SVR models exhibited the highest correlation coefficients among all models, with 0.9748 and 0.9276 for the training and test sets, respectively. The findings suggested the potential of FeTPP-based fluorescent sensor in rapid monitoring of frying oil quality and perhaps also in other foods with higher oil contents.

Effect on rheology and frying stability of edible oil before and after addition of fenugreek seeds

Rheological parameters of vegetable oils showed great changes during frying. The correlation between rheological behavior and viscosity measurements during frying can give a good overall estimate of frying oil quality. In the present study, rheological properties of rice bran oil (RBO) and soybean oil (SBO) during deep-frying of 13 ​min were investigated for consecutive 1st, 2nd, 3rd, and 4th frying at an interval of one week. To enhance the frying stability of RBO and SBO, fenugreek seeds (Trigonellafoenum graecum) was added during frying. The shear stress versus shear rate data was fitted to Newtonian and Herschel-Bulkley rheological models. The flow behavior of RBO and SBO with and without fenugreek seeds in before and after frying were measured at 30 ​± ​2 ​°C. The increase in viscosity, acid values and flow behavior index (n) with frying times for both RBO and SBO can be controlled with the addition of fenugreek seed up to 3rd frying with n ​< ​1 values, where without fenugreek seeds for RBO and SBO it showed a shear thickening properties (n ​> ​1) after 2nd and 3rd frying respectively.

Effects of vacuum frying on the quality of king orange peel in manufacture of chocolate candy fillings

Deep-fried orange peel applied vacuum-frying technique to extend its shelf life and to create crispy product that contains natural nutrients, especially looking for marketplace of the product and increasing the value of orange by-products. The effects of vacuum frying conditions on the quality of fried orange peel was evaluated to produce nutritional chocolate candy fillings that has good sensory values. Orange peel slices were fried under vacuum (20 in of Hg) using sunflower frying oil at various temperatures (80°C, 85°C, 90°C, 95°C and 100°C) for different amounts of time (5, 10, 15, 20, 25 and 30 min). After frying, the fried orange peel slices were centrifuged at 140 - 1000 × g for 4 min to remove the frying oil. Results of this study suggest that vacuum frying at 100°C for 30 min showed maximum shrinkage (48%) and 95% of carotenoids were lost. The hardness of fried orange peel increased during the frying process. Sensory evaluation showed maximum acceptability for fried orange peels at 90°C for 25 min. The TBARS indicated a high deterioration in the atmospheric frying oil quality. In contrast, the vacuum frying condition helped preserve the frying oil quality, while the light color of the product was maintained. The results supported the use of the vacuum frying process as a method for frying high quality king orange peel and conserving the quality of oil in the king orange peel.

Changes in fatty acids and formation of carbonyl compounds during frying of rice cakes and hairtails

This study investigated the effects of frying of foods on the fatty acids and formation of carbonyl compounds in frying soybean oils. Rice cakes and hairtails were selected as typical starch/protein-based foods for frying using soybean oil. In this study, fifteen carbonyl compounds were detected by an efficient high performance liquid chromatography (HPLC) developed by this paper. During frying with rice cakes or hairtails, the linolenic acid in frying oils was reduced by approximately 20 % compared with that in the no-food frying system. Fewer types of carbonyl compounds (frying without food: 11; frying of rice cakes: 9; frying of hairtails: 6) were detected, and the levels of some carbonyl compounds such as trans-2-nonenal were decreased. Results suggested that frying rice cakes or hairtails can substantially influence the contents of fatty acids and the formation of carbonyl compounds in frying oils. This study provides references for evaluating the quality of fried oil and food.

Improving the quality of used frying niger seed oil with adsorbent treatment

High temperature continuous deep fat frying of foods will result in the frying oil and food quality deterioration. Although the quality can be retained by using fresh oil, this approach will increase the production cost. In this study, quality improvement of used niger seed oil using adsorbent treatment was evaluated. Each adsorbent was mixed with 20 h used niger seed oil (15% w/v) at 150 °C and stirred for 30 min. The oil was recovered through centrifugation at 4200 rpm for 15 min. The tested chemical parameters of the oil increased after 20 h of frying (acid value (AV) (2.24–8.31) mg KOH/gm oil, free fatty acid (FFA) (1.13–4.17) %, and peroxide value (PV) (1.00–13.97 mEq oxygen/Kg of oil). The improvement in free fatty acid, peroxide value and oil recovery upon treatment of the fried oil with ash, bentonite, bleaching earth, silca gel and magnesium oxide (MgO) was (61, 57, 80), (66, 43, 88), (56, 21, 85), (61, 50, 70), and (73, 64, 40) % respectively. Ash and MgO effectively improved the physico-chemical characteristics of the used oil. Thus, the two were selected for further optimization of effective concentration and to evaluate their synergetic effect. Treatments with 2.5, 5.0, 7.5, 10.0, 12.5 and 15.0 % of ash reduced the AV of the fried oil by 26, 39, 46, 53, 53 and 60 % respectively (p < 0.05). Also the combination of ash and MgO (1:1) improved the physico-chemical properties of the frying oil to nearly fresh quality.

Effect of Vacuum Frying Conditions on Quality of French Fries and Frying Oil

Vacuum frying conditions were investigated with respect to physical, chemical and sensorial properties of French fries and frying oil, besides determining the effect of frying conditions in terms of frying temperature and time. In order to determine the optimum frying conditions of the French fries optimization study was carried out according to Central Composite Rotatable Design. The results were evaluated to determine optimum vacuum frying conditions targeting minimum oil content, 30-45 N in range of hardness, minimum acrylamide content and maximum overall preference. The optimum vacuum frying condition was selected as 124.39 °C of frying temperature and 8.36 min of frying time for French fries. The French fries obtained at optimum conditions for vacuum frying preserved the desired color, textural properties and flavor and it has low oil content and reduced acrylamide formation. In addition, the frying oil quality was preserved with vacuum frying.

A novel rapid method for the determination of frying oil quality: development of prototype and equations and examination with respect to legislation criteria

SummaryThe present work presents a prototype apparatus developed for a novel method based on capillary penetration for the determination of frying oil quality and examines the method and the performance of the prototype. The work further assesses the method results in comparison with the results of established methods and proposes equations for calculating frying oil quality parameters relevant to legislation criteria. The examination of the method is performed by using 184 oil samples produced by frying different foods in different oils for forty‐five successive batches. Equations relating the method output with the total polar compounds, total polymers and viscosity are proposed. High correlation coefficients between legislation criteria and the method result are obtained: R2 = 0.96, R2 = 0.91 and R2 = 0.86 for correlation with the oil viscosity, the polymer compounds and the TPC of the fried oils, respectively. The false‐positive and false‐negative answers of the method are below 2.5% for all cases.

Investigating the Changes in Physicochemical and Oxidative Properties of Different Brands of Sunflower Oil Sold in Market Before and After Frying

Oils and fats for commercial frying applications can lead the changes caused by oxidation, polymerization, or hydrolysis during high-temperature processing. Deep frying is one method which involves submerging the food in hot oil. During oxidation can lead to the formation of potentially toxic oxidation products. This lipid per oxidation products generates that may be harmful to human health and it is necessary to monitoring of the frying oil quality degradation, therefore, is an important issue for both food frying operators and food control/regulatory agencies. In this study, The changes in the physicochemical properties of eight different brands of sunflower oils were analysed (before and after frying) using standard procedures of AOAC and AOCS. The experimental results obtained that,RI and specific gravity and colour were in the range of 1.4658-1.4720,0.9018-0.8848 and1.82-16.6 before and after frying. AV and PV were ranged between 0.22-0.54 in fresh oils,0.85-1.21in after frying and 2.4-4.1and 8.18- 13.15 mg KOH/g before and after frying oil while SV and EV were ranged between 189.98-193.12 and 189.62- 192.67 mg KOH/g oil in fresh oils and in between 198.68- 202.18 and 197.71-200.97mg KOH/g oil in after frying oils respectively. P-AV and TV were in the range of 3.9- 5.01 and 8.79-13.21 in before frying while in case of after frying it is 9.16-13.15 and 25.52-38.55 meq/kg respectively. In general, after frying, RI, colour,AV,PV,P-anisidine and totox values were found higher and deviates codex standards and specific gravity and iodine values are lower than as compared with safety limit. The results showed degradation in the physico-chemical properties of the vegetable cooking oil after frying

Rapid Assessment of Total Polar Material in Used Frying Oils Using Manganese Tetraphenylporphyrin Fluorescent Sensor with Enhanced Sensitivity

Probe-based three-dimensional fluorescence spectroscopy was developed for the rapid assessment of frying oil quality. Tetraphenylporphyrin manganese (MnTPP) was selected due to its sensitivity and selectivity in response to dissolved organic matter, which is typically produced during the frying process of oil analyte. Parallel factor analysis (PARAFAC) was then performed to decompose three-dimensional fluorescence data for model construction. The digital data representing the change of the MnTPP-base fluorescent probe before and after exposure to dissolved organic matter were analyzed using support vector regression (SVR). SVR was then used for the construction of the regression model between the fluorescence data and the total polar material (TPM). The coefficients of determination (R2) in the training set (R2 = 0.9719) and the test set (R2 = 0.9699) were achieved to evaluate the robustness of the best models for TPM. This study demonstrated that the probe-based three-dimensional fluorescence spectroscopy is useful for assessing the quality of frying oil and perhaps could be used for other food products with high oil contents.

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.

Ultrasonic shear‐wave reflectometry applied to monitor the dynamic viscosity of reheated edible oil

AbstractEffects of frying cycles of two types of edible oil on dynamic viscosity were studied by ultrasonic shear‐wave reflectance method. Factors affecting the reflection coefficient were analyzed theoretically. The experimental methods and parameters are carefully analyzed and optimized in the low‐viscosity case. The viscosity of the reheated oil samples was characterized by the reflection amplitudes at (25 ± 0.2)°. Three methodologies for data post‐processing were used to calculate the reflection magnitudes. The results show that viscosity increases with repeat times of heating. The viscosity obtained by the integral ratio in a frequency band is closer to those obtained by rheometers than those from central frequency and multiple reflection. It indicates that the shear‐wave reflectometry can be extended further used to measure low‐viscosity liquids by appropriate signal processing. In addition, the heating times of a given procedure is highly correlated with the viscosity of edible oil (R2 &gt; .93). We also attempted to evaluate the oil deterioration by predicting the amounts of carbonyl and fatty acids based on the relationship between viscosity and indicator content.Practical ApplicationsViscosity is an important physical property and a quality index of edible oil. Not only viscosity changes, aging, and decay phenomena will even occur in the process of repeated heating of edible oils at high temperature. As a convenient and nondestructive method, the ultrasonic shear‐wave reflectance method can realize the rapid detection of the viscosity of reheated oils in situ. Therefore, this method has the potential to monitor frying oil quality online, which is expected to evaluate the degree of aging and deterioration of reheated edible oil.

Forward and backward interval partial least squares method for quantitative analysis of frying oil quality

The edible oil that has been fried several times would not only affects the taste of the fried food but also reduces the quality of the fried oil. In view of the quality of frying oil, this paper proposed to use near-infrared spectroscopy (NIRS) to detect the quality of frying oil under standard operation and to convert the quality of frying oil to the frying times under standard operation, that was, the relationship between NIRS and standard operation times was established. The quality of the frying oil was indirectly detected by the frying times under standard operation. Firstly, soybean oil was used as frying oil and frozen French fries as frying materials. Ten experiments were carried out. Each frying experiment was repeated frying 15 times with no added unused oil to obtain spectra of different frying times. The best pre-processing method was chosen by establishing a partial least squares (PLS) model. Then, the pre-processed spectra were divided into different intervals. Forward interval partial least squares (FiPLS) and Backward interval partial least squares (BiPLS) were used to screen the feature intervals, and the genetic algorithm (GA) was used to optimize the selected feature interval to obtain the characteristic wavelengths. Finally, the model was evaluated by the determination coefficient (R2), predicted root mean square error (RMSEP) and relative analysis error (RPD) to determine the best model. The results showed that when the spectrum was divided into 40 sub-intervals, the 21 joint sub-intervals selected by FiPLS method were optimal. Then the GA was used to optimize 21 joint intervals, and the optimal characteristic wavelengths modeling were selected. The obtained R2, RMSEP, RPD were 0.9994, 0.1060, 40.7021, respectively. Therefore, the method used in this paper could quickly and accurately identify the quality of frying oil, and this study also provided a convenient and efficient method for the detection of the quality of frying.

Quality parameters of different oils and fried foods after repeated deep-fat frying

The aim of present study was to investigate the quality, stability and suitability of different frying oils (coconut, palm, frying mix, rapeseed and sunflower oil), the quality and stability of breaded and fried foods (chicken nuggets) and the applicability and suitability of certain parameters (fat absorption, acid number, peroxide number and thiobarbituric acid (TBA) number, fatty acid composition and acrylamide content) as well as sensory attributes to control the repeated deep-(fat) frying process. Three repeated deep-frying processes affected the hydrolytic and oxidation stability (increase in the peroxide number and TBA number), the sensory properties (darkening of the oil colour, occurrence of odd smell and aroma as well as rancidity in oils) and the fatty acid composition of oil and fried chicken nuggets, and the acrylamide content in the nuggets (from the second deep-frying process onwards). All oils used in study were suitable for deep-frying; in terms of stability, coconut oil (followed by sunflower, palm, frying mix and rapeseed oil) was most suitable; in terms of fatty acid composition, the frying mix, rapeseed and sunflower oil were most suitable; and in terms of acrylamide formation and sensory quality, coconut and palm oil were most suitable.