Oil Quality Research Articles

Study on the structure, stability characterization, and oxidative stability of a conjugated stabilized walnut oil emulsion using walnut protein isolate and gum Arabic

Walnut oil (WO), often referred to as “Oriental olive oil," is renowned for its numerous biological benefits, including memory enhancement and the prevention of cardiovascular and cerebrovascular diseases. However, WO is prone to oxidation during processing, which leads to a decline in oil quality. Due to the weak functional properties of walnut protein isolate (WP), a WP-gum acacia (GA) conjugate (WP-GA) was prepared by modifying the WP surface to stabilize walnut oil emulsion. Results showed that WP-GA, at a concentration of 2 g/100 g protein, could form a stable and fully emulsified emulsion. Compared to the walnut protein-stabilized emulsion (WP-WO), the WP-GA conjugate-stabilized WO emulsion (WP-GA-WO) exhibited larger particle size, a higher absolute zeta potential, reduced turbidity, and a higher percentage of adsorbed protein. Rheological analysis revealed that WP-GA-WO had a higher energy storage modulus compared to WP-WO, indicating improved elasticity and viscosity due to glycosylation of the emulsion. Additionally, the WP-GA-WO emulsion demonstrated enhanced thermal, pH, ionic strength, salt stress, and storage stability, as evidenced by delayed oxidation of α-linolenic acid and linoleic acid. In vitro digestion assays showed that the WP-GA conjugate emulsion had better stability in gastric juices. These findings suggest potential applications for WP and GA in food-related fields.

Synergistic effects and comprehensive analysis of interaction during infrared co-pyrolysis of furfural residues and PVC

Infrared co-pyrolysis was employed to convert waste into valuable resource due to the increasing production of plastic waste. In this study, support vector machine (SVM) accurately predicted PVC and furfural residues thermal behavior. The results showed high accuracy (R2 > 0.95) after the SVM model was trained and validated. Furthermore, this research performed an in-depth characterized of the co-pyrolysis process using various analytical techniques, indicting TG-FTIR-GC/MS, XPS, simulated distillation, and GC/MS. As the temperatures and heating rates increased, the pyrolysis oil yield increased at first and then declined, reaching a maximum of 37.7 % at 600 °C and 10 °C/s. Notably, aromatic content was relatively high, comparing with other components, whereas the chlorinated content remained relatively low, all below 6.5 %, indicating the pyrolysis oil quality had effectively improved. According to the results of XPS, there was a significant 64.11 % increase in inorganic chlorination, which suggested the effective reduction in gaseous chlorine emission and achieving chlorine immobilization.

Water Separation and Formation of Cells with Differential Aeration as Factors Controlling Corrosion of Steel Pipelines in a Crude Oil Storage Facility

The mechanism causing the dramatic intensification of the corrosion deterioration of carbon steel pipes in a crude oil storage facility has been investigated. This study considers a number of factors affecting corrosion in crude oil, such as the water content, the corrosivity of the aqueous phase, the kinetics of water–oil separation, the effect of dissolved oxygen, the effect of the crude oil quality, the degree of stagnancy inside of the pipes, the possible contribution of microbially induced corrosion (MIC) and the presence of deposits. The key root of the corrosion intensification was the separation of the water phase, supported by stagnancy, which eventually led to the formation of stable shallow pits surrounded by cathodic areas.

The Physicochemical and Nutritional Analysis of Coconut Oil (Cocos nucifera) Extracted from the Tall Tree Variety

Aims: Coconut (Cocos nucifera) known as the ‘tree of life’ is an ancient fruit belonging to the palm family Arecaceae family and the only species in the genus Cocos. This study aims to characterize and show the nutritional qualities of coconut oil from the tall tree variety. Methodology: The production methods include natural Fermentation, centrifugation, freeze-thawing, and solvent extraction. In physical and chemical properties, the moisture content, impurity, specific gravity, refractive index, oil yield, flash, fire, smoke point, melting point, thiobarbituric acid number, saponification, peroxide, iodine, and fatty acid value were analyzed and all fall within close ranges. Results: The fat-soluble vitamins ranged from 18.65 ± 5.09 (vitamin A), 4.28 ± 0.68 (vitamin E), 4.11 ± 3.11(vitamin D) and 1.03 ± 0.21 (vitamin K) all in mg/100ml. Mineral analysis shows that coconut oil contains calcium, zinc, and iron with concentrations of 2.53 ± 0.23, 1.21 ± 0.19, and 0.53 ± 0.13 in mg/100ml respectively. Fatty acid analysis shows that coconut oil contains lauric, myristic, palmitic, caprylic, oleic, capric, stearic, linoleic, and caproic acid of which lauric acid was the highest with a range of 48.40 ± 0.23. Conclusion: The result shows that coconut is a good source of nutrients and the fatty acids make it a good moisturizer.

A review of potential fault detection methods for traditional collector stations and sensor fault diagnosis in wind farm doubly-fed generator converters

Collector stations sometimes face situations where existing relay protection systems may fail, making potential fault monitoring technology increasingly important. This technology plays a critical role in ensuring the stability of power supply and enhancing economic benefits. Simultaneously, in response to the nation's "dual carbon goals," the construction and operation of large-scale renewable energy power stations are booming. Therefore, potential fault monitoring technology for new power stations should not be overlooked. For traditional power stations, the application and development trends of infrared thermal imaging technology, vibration analysis and acoustic detection technology, chemical analysis, and oil quality detection technology will be compared and discussed. Regarding new power stations, methods for diagnosing sensor faults in doubly-fed generator converters in wind power will be analyzed and discussed.

MICROWAVE HEATING EFFECT ON THE OXIDATION AND QUALITY OF COLD-PRESSED SUNFLOWER OIL

Sunflower oil is widely used in the human diet, primarily due to its constituent components and its applications in producing functional products. The use of microwave ovens in food preparation has become widespread in recent years due to certain advantages that include saving time, energy and convenience. As a result of heat treatment of oils, various chemical reactions can occur, leading to the formation of products that may indicate deterioration or a reduction in quality. For this purpose, untreated oil (not subjected to heating) and oil heated in a microwave oven for varying durations (ranging from 4 to 20 minutes) were analyzed in this study. The quality assessment of cold-pressed sunflower oil was conducted using standard official methods to measure peroxide, acid, and iodine values. The progression of oil oxidation was tracked by analyzing conjugated dienes and conjugated trienes through UV-spectroscopy (method AOCS Ch 5-91). Additionally, considering the theoretical link between microwave heating and changes in fatty acid composition, the fatty acid profile of the oil was determined according to MKC EN ISO 12966-4:2015. The results indicate a notable shift in the peroxide value (PV). Specifically, after heating the oil for 4 minutes, the PV exceeds the permitted limits. Furthermore, a decrease in the iodine value is observed with increasing heating time, while no significant changes are noted in the acid value. Additionally, changes in the content of fatty acids are observed in cold-pressed sunflower oil. At specific wavelengths (232 and 268 nm), conjugated dienes and trienes were detected as oxidation products, i.e. the extinction coefficients (K232) and (K268) fell within the ranges of 3,72-4,16 and 1,25-2,56, respectively. These findings lead to the conclusion that microwave heating induces changes in the quality of cold-pressed sunflower oil. To maintain its quality, an appropriate choice of heat treatment is required.

1H NMR chemometrics and mechanistic insights on the thermal degradation of coconut oil

AbstractThe re‐use and prolonged heating of cooking oils is a common practice in preparing deep‐fried foods. However, this could be unsafe and pose a health threat to consumers. This work investigates the thermal degradation of edible coconut oil under prolonged heating using chemometrics analysis of proton nuclear magnetic resonance (1H NMR) data. Coconut oil samples were heated continuously without food matrix at three different temperatures (150, 175, and 200°C) for 12 h and the 1H NMR spectra were collected every hour. NMR data revealed the formation of aldehyde oxidation products. Partial least squares discriminant analysis (PLS‐DA) discriminated the samples based on temperature and heating time. The Variable Importance Projection revealed the discriminating peaks highlighting the spectral feature due to hydroperoxides and aldehydes in the oil degradation. A probe into the 1H NMR of the degradation products of saturated coconut oil confirmed the formation of a ketone as evidenced by a CH2 triplet in the chemical shift region of protons alpha to a ketone. The results showed that the thermal degradation of coconut oil was influenced by temperature, time, moisture, and oxygen in the air which can contribute to the advancement in the control and assessment of coconut oil quality.

Comprehensive electrochemical and machine learning-based study of rancidity in four edible oils over various storage periods

This study investigates the rancidity development in four edible oils (corn, mustard, soybean, and sunflower) over a 12-month storage period using a novel approach combining electrochemical techniques and machine learning. Cyclic voltammetry, electrochemical impedance spectroscopy, and differential pulse voltammetry were employed to characterize oil oxidation. Electrochemical parameters showed strong correlations with traditional chemical indicators, such as the DPV peak current at +0.2 V with p-anisidine value (r = 0.94, p < 0.001). A Random Forest model, trained on electrochemical data, accurately predicted Total Oxidation (TOTOX) values, achieving an R² of 0.96 and RMSE of 2.18 for the test set. The model effectively captured oxidation trends across oil types, with the highest accuracy for mustard oil (MAE: 1.21) and lower performance for sunflower oil (MAE: 2.15). Feature importance analysis revealed charge transfer resistance and DPV peak currents as the most influential predictors. This approach offers rapid, non-destructive assessment of oil quality, potentially improving quality control in the food industry. However, challenges such as electrode fouling and complex sample preparation need to be addressed for practical implementation.

Physicochemical and sensory evaluation of the quality of crude palm oil (Elaeis guineensis) produced artisanally and industrially in Brazil

Palm oil is primarily used in the crude form in northeastern Brazil's cuisine. Most of its production is carried out by small manufacturers, who use the profits from sales as a subsidy to supplement their family income. Evaluating the physicochemical and sensory quality of palm oil is essential to help producers develop higher-quality artisanal products. This study aimed to analyze samples of crude palm oil produced and sold in the city of Taperoá (BA) and other industrialized brands sold in Salvador (BA). Seven palm oil samples underwent physicochemical analysis (acidity, carotenoid content, instrumental color, iodine value, peroxide value, Kreis reaction, saponification value) and sensory analysis (acceptance and ranking tests). Our findings revealed significant variation in the evaluated parameters, with most samples showing inadequate results for the regulatory parameters of acidity and iodine values, as well as unsatisfactory results for carotenoids and the Kreis reaction across all samples. Variations in color analysis were likely associated with differences in carotenoid content among the samples. The acceptance tests showed that most samples scored above average for all evaluated characteristics, except for the industrial sample from Taperoá (sample 06), which showed the lowest averages for color (4.5), odor (5.2), viscosity (3.2), and overall impression (4.3). In the ranking test, sample 02 from artisanal production (Taperoá-BA) was the most preferred in all categories, while sample 06 from industrial production (Nazaré-BA) was the least preferred in all categories. These results indicate opportunities for improving both traditional and industrial crude palm oil production methods, which could lead to an increase in income for the population that depends on this product.

Characterization and Encapsulation Methods for Pomegranate Seed (P. Granatum) Oils, Review

The use of bioactive components in herbal products across different industries is growing.As a result, ecologically friendly techniques such simple mixing, pressure-assisted extraction, enzymatic extraction, ultrasound-assisted extraction, pulsed electric fields, high hydrostatic pressure, ohmic heating, and microwave-assisted extraction are being investigated. These methods enhance the equipment design, extraction efficiency and extraction method of bioactive constituents with organic solvents. Consequently, encapsulation techniques preserve oil quality and other pomegranate seed components. Encapsulation enables the safe delivery, preservation and regulation of the targeted release of bioactive constituents in food systems. This study provides information on encapsulation techniques that protect sensitive compounds and their benefits. Increasing problems related to food quality, safety and reliability cause undesirable effects on product quality. Capsulation and ecological methods are expected to achieve food safety and reliability goals in the future effectively.

Influence of diurnal harvesting times on essential oil yield and chemical composition of lemongrass, palmarosa and tulsi

Essential oil yield and chemical composition of most of the aromatic crops are affected by environmental, agrochemical and genetic factors. One of such factors are Harvesting Time (HT’s), optimizing which may result in higher essential oil production with better quality. The present study was carried out to determine the effect of HT’s on three different aromatic crops [lemongrass, palmarosa and Ocimum sanctum (CIM-Ayu)] at different diurnal times (9.00 A.M 12.00 P.M and 3.00 P.M) in a day and the same was repeated thrice on alternate days from in the same fields. The results indicated that HT at 3.00 PM had higher essential oil content in all the three aromatic crops. But, the influence of HT on the quality of essential oil was specific to the different crops studied in this report. The quality of essential oil obtained from lemongrass harvested at 12.00 PM was found to be better as it showed more percentage of citral whereas the essential oils obtained from palmarosa and O. sanctum harvested at 3.00 PM were better as they showed more percentage of geraniol and eugenol respectively. This research not only refines essential oil production strategies but also underscores the crop-specific impact of harvesting times. The meticulous temporal analysis, coupled with statistical validation, contributes novel insights, providing practical benefits for industries reliant on these aromatic crops.

Interplay of phenolic compounds and gene expression in phenylpropanoid and flavonoid pathways during olive (Olea europaea L.) ripening of ‘Leccino’ cultivar

This study presents a detailed analysis and interplay of the phenolics, relative gene expression and quality parameters during ripening of ‘Leccino’ olive fruit pulp and skin at seven maturity indexes, in the phenylpropanoid and flavonoid pathways. Tissue-specific gene expression analysis revealed statistically higher expression levels for eight genes in the skin. The only exception was anthocyanidin synthase (ANS), which expression level was statistically higher in the pulp. Our results confirm that the important role in olives of the anthocyanin composition have flavonoid 3′-hydroxylase (F3′H) and flavonoid-3′,5′-hydroxylase (F3′5′H) in both tissues. The phenolic content was mostly statistically higher in the skin than in the pulp and generally increased in both tissues during ripening. A notable shift in phenolic compounds occurs between maturity index 3 and 4, when the skin of the fruit turns completely purple. Results from this study highlight the intricate dynamics of physiological processes and biochemical mechanisms in the phenylpropanoid and flavonoid pathways in olive fruit. The findings also underscore the relationship between phenolic content, relative gene expression, and quality parameters, particularly in relation to color development during ripening in different olive fruit tissues. Our conclusions can be used by growers to improve the quality of fruit and consequently the quality of olive oil or other final products.

Promoting salt tolerance, growth, and phytochemical responses in coriander (Coriandrum sativum L. cv. Balady) via eco-friendly Bacillus subtilis and cobalt

In plant production, evaluation of salt stress protectants concerning their potential to improve growth and productivity under saline stress is critical. Bacillus subtilis (Bs) and cobalt (Co) have been proposed to optimize salt stress tolerance in coriander (Coriandrum sativum L. cv. Balady) plants by influencing some physiological activities. The main aim of this work is to investigate the response of (Bs) and (Co) as eco-safe salt stress protectants to resist the effect of salinity, on growth, seed, and essential oil yield, and the most important biochemical constituents of coriander produced under salt stress condition. Therefore, in a split-plot factorial experiment design in the RCBD (randomized complete block design), four levels of salinity of NaCl irrigation water (SA) were assigned to the main plots; (0.5, 1.5, 4, and 6 dS m−1); and six salt stress protectants (SP) were randomly assigned to the subplots: distilled water; 15 ppm (Co1); 30 ppm (Co2); (Bs); (Co1 + Bs); (Co2 + Bs). The study concluded that increasing SA significantly reduced coriander growth and yield by 42.6%, which could be attributed to ion toxicity, oxidative stress, or decreased vital element content. From the results, we recommend that applying Bs with Co (30 ppm) was critical for significantly improving overall growth parameters. This was determined by the significant reduction in the activity of reactive oxygen species scavenging enzymes: superoxide dismutase (SOD), catalase (CAT), and malondialdehyde (MDA) and non-enzyme: proline by 5, 11.3, 14.7, and 13.8% respectively, while increasing ascorbic acid by 8% and preserving vital nutrient levels and enhancing plant osmotic potential to buffer salt stress, seed yield per plant, and essential oil yield increased by 12.6 and 18.8% respectively. The quality of essential oil was indicated by highly significant quantities of vital biological phytochemicals such as linalool, camphor, and protein which increased by 10.3, 3.6, and 9.39% respectively. Additional research is suggested to determine the precise mechanism of action of Bs and Co's dual impact on medicinal and aromatic plant salt stress tolerance.

Redesigning soybean with improved oil and meal traits.

Soybean seed oil and meal composition traits can be combined without interference to provide additional value to the crop. Soybean [Glycine max (L.) Merr.] is an important crop worldwide; its overall value comes from seed oil and high protein meal. The development of soybean varieties with allele combinations for improved oil and meal quality is expected to provide a compositional value bundle for soybean. The high oleic and low linolenic acid seed oil trait (HOLL; > 70% oleic and < 3% linolenic acid) is targeted to optimize the health and functional properties of soybean oil. For soybean meal, metabolizable energy is improved by altering the carbohydrate profile with increased sucrose and decreased anti-nutritional factors, raffinose family of oligosaccharides (RFOs). Previous research identified four variant alleles of fatty acid desaturase (FAD) genes and two raffinose synthase (RS) genes necessary for the HOLL trait in soybean oil and Low or Ultra-Low (UL) RFO traits in soybean meal, respectively. We employed a molecular marker-assisted breeding approach to combine six alleles conferring the desired soybean oil and meal value traits. Eight environment field trials were conducted with twenty-four soybean lines to evaluate phenotypic interactions among the variant alleles of FAD and RS genes. The results indicated that the four FAD gene alleles conditioned the HOLL fatty acid profile of the seed oil regardless of the allele status of the RS genes. Independent of the allele combination of the FAD genes, soybean with two variant alleles of the RS genes had the desired RFO trait in the seeds. The results confirm the feasibility of soybean variety development with this unique combination of oil and meal traits.

QTL mapping and epistatic interactions for improved seed oil quality in safflower

QTL mapping and epistatic interactions for improved seed oil quality in safflower

Impact of Extended Intervals on Diesel Engine Performance with 15W-40 DH1 Lubricant Oil

Engine lubricant oil is crucial for minimizing friction between moving components within an engine, directly influencing the engine's reliability and lifespan. Determining the appropriate oil replacement intervals is essential, as extending these intervals necessitates more rigorous monitoring of both oil quality and engine condition. This study investigated the performance of SAKAI 15W-40 DH1 engine oil in the SAKAI Vibrating Roller SV526 over varying operational periods: 125 hours, 250 hours, 375 hours, and 500 hours. The research involved analyzing oil samples for viscosity, metal additives, total base number (TBN), and contaminants using Fourier Transform Infrared Spectroscopy (FTIR). Additionally, key engine performance indicators, including fuel consumption, valve clearance, and compression pressure, were measured. The findings revealed a gradual decrease in oil viscosity from 13.48 cSt to 11.56 cSt, approaching the minimum acceptable threshold of 11.45 cSt. Concurrently, the Fe content in the oil increased to 11 ppm, indicating wear, while the valve clearance in cylinder number three expanded to 0.48 mm, and compression pressure dropped from 31 kg/cm² to 28 kg/cm². Despite these changes, the oil remained within the standard operational limits, and the engine continued to perform adequately. However, based on the observed trends, extending the oil replacement interval to 500 hours cannot be conclusively recommended, as the oil's condition and engine performance may begin to decline beyond this point.

Ultrasound- and Homogenization-Assisted Extraction of Cottonseed Oil Using Ethyl Acetate: Optimization and Evaluation of Oil Quality and Energy Aspect

Ultrasound- and Homogenization-Assisted Extraction of Cottonseed Oil Using Ethyl Acetate: Optimization and Evaluation of Oil Quality and Energy Aspect

Production and characterization of two-step condensation bio-oil from pyrolysis

The goal of this project is to investigate the potential of fuel production directly from slow pyrolysis of straw pellets without further refining. A two-step condensation was used to separate liquids from the volatiles. The thermal process chosen is slow pyrolysis at 500°C to couple the fuel production with carbon capture by maximizing the char production alongside bio-oils collection. Condensation parameters were tuned to improve the pyrolysis oil quality. To assess the oil quality some requirements on marine fuels, bio-oils and boiler fuels were taken as reference. Three condensation conditions were inspected: the best pyrolysis overall process was repeated three times for a total of five pyrolysis processes (lately referred to as runs). As expected, the bio-oil characteristic changed with the condensation temperature. As a result of lowering the bio-oil condensation temperature, the bio-oil results less viscous, less dense, with lower heating value and with higher water content. The final bio-oil produced was almost compliant to ISO 8217:2017 for residual marine fuels K 380, apart from water content and acid number, while it was almost compliant for the standard EN 16900:2017 for industrial boilers fuels, apart for the kinematic viscosity. It was assessed that the char is produced with an average yield of 27 w% on dry basis, while bio-oil has a yield between 5 and 10 w%. It is possible to recover an average of 72 % of the total energy contained in the straw in the valuable products, gas, char and bio-oil. The carbon captured with charcoal was around 49 w% of the total present in straw. The pyrolysis experiments were performed using an innovative semi-batch, packed-bed reactor with gas re-circulation and a new two-fraction condensation appliance that is DTU patented. The innovation is both in the reactor, where the gas is directly heated and flushed back into the pyrolyser, and in the condensation section, where the bio-oil is separated from the water fraction during the pyrolysis. The company Stiesdal SkyClean A/S showed interest in further development and scale up of this pyrolysis and condensation system.

Investigating the potential of aqueous enzymatic extraction of safflower (Carthamus tinctorius L.) seed oil: Process optimization and oil characterization

Safflower seed oil was extracted by aqueous enzymatic extraction (AEE) with a combination of three enzymes: hemicellulase, pectinase, and protease. A Response Surface Methodology (RSM) was performed to optimize the operating conditions: Temperature, pH, and incubation time. Analysis of variance allowed studying the variables' linear, quadratic, and interaction effects. The optimized extraction conditions resulted in 85% oil recovery referring to the conventional Soxhlet extraction (SE). Subsequently, a comparative analysis was conducted to evaluate the quality and composition of oils obtained by SE and AEE. The results revealed that the two oils had similar values of peroxide index, conjugated dienes and trienes, and fatty acid composition. AEE-oil had a lighter yellow color (L* = 31.8 Vs. 24.7) and was richer in polyphenols (147 Vs. 101 mg GAE/Kg of oil), but it was more acidic (2.75% Vs. 1.56% linoleic acid) and less stable (2.86h Vs. 5.66h induction time) with less tocopherol (302 Vs. 409 mg/kg oil) and carotenoid content (0.42 Vs. 0.57 mg/kg oil) than SE-oil. Our findings demonstrated that RSM-based optimization is an efficient and time-saving approach, which significantly improved oil extraction. Finally, we suggested several solutions to further improve the quality and quantity of the obtained AEE-safflower seed oil, paving the path for other future research possibilities.

Employment of MQ gas sensors for the classification of Cistus ladanifer essential oils

The chemical composition of essential oils (EOs) from Cistus ladanifer has a huge variability throughout the year, impacting the oil quality. Nowadays, EO analytic chemistry techniques, which are expensive and destroy the sample, are utilized to measure the chemical composition. In the paper, we propose a combination of low-cost sensors and machine learning based system. As low-cost sensors, seven gas sensors are combined to obtain up to 36 features. Regarding machine learning, 31 multiclass classification algorithms are applied. Data from sensors were collected for 33 samples of EO from Cistus ladanifer. The generated dataset was split into training and test datasets, with 75 % of the data for training. The datasets were created to ensure a homogeneous chemical composition distribution on both training and test datasets. There were three target chemical compounds: Alpha-pinene and Viridiflorol as individual compounds and Terpenic Hydrocarbons as a group of chemical compounds. The value of the percentage of each targeted compound is converted into a categoric variable with 5 possible values, 1 being the lowest concentration and 5 being the maximum one. The data of the MQ-sensors were included as the input for the models, and each one of the targeted chemical compounds was selected as an output for different models. The input features were ranged using different algorithms for the feature selection process. The results indicate that there is no valid classification model for Viridiflorol, and limited accuracy is achieved for Alpha-pinene. Meanwhile, for Terpenic Hydrocarbons, an accuracy of 91.6 % is achieved. It is important to highlight that these accuracies were attained when a reduced number of features were included, ranging the number of features from 11 to 13. This is the first case in which MQ-based gas sensors, or other metal oxide sensors, are used to correctly determine the concentration of a chemical compounds in a complex matrix formed by dozens of compounds. This system will provide a cheap method to determine the quality of EOs and confirm the benefits of combining low-cost sensors with machine learning.