The mathematical prediction model for the oxidative stability of vegetable oils by the main fatty acids composition and thermogravimetric analysis

Physicochemical analysis of beef tallow and its liquid fraction, comparing frying performance with high oleic acid rapeseed oil and rice bran oil

Fractionation allows the separation of components in beef tallow. This study compared the physicochemical characteristics and cholesterol content of beef tallow and its liquid fraction, evaluating their frying performance as potential deep-fat frying oils against plant oils. Results showed effective separation of unsaturated components from beef tallow through fractionation. Beef tallow exhibited superior physicochemical properties during frying, with lower deterioration levels than plant oils. Benzo[a]pyrene content increased in plant oils but remained low in beef tallow and its liquid fraction. The liquid fraction had a significantly shorter oxidative induction time of 0.38 h compared to 5.85 h and 5.24 h for plant oils. This study revealed that alterations were observed in beef tallow and its liquid fraction when used as frying oils, with beef tallow demonstrating stronger antioxidative properties compared to the liquid fraction, which exhibited lower levels of cholesterol and saturated fatty acids.

Lipids from the purple and white açaí (Euterpe oleracea Mart) varieties: nutritional, functional, and physicochemical properties

The Brazilian superfruit called Açaí or Assaí has gained interested from researcher and consumers worldwide, due to its health-related properties. In this context, this pioneering study aimed to compare the physicochemical, nutritional, and thermal properties of vegetable oils obtained from two varieties of açaí (Euterpe oleracea), purple and white. Both açaí oils from white (WAO) and purple (PAO) varieties were obtained by using the conventional solid-liquid extraction, which resulted in oil yields ranging from 52 to 61%. WAO and PAO were analyzed by their edibility quality parameters given the recommendations from Codex Alimentarius; their nutritional functionality indices and their composition of fatty acids and triglycerides content were estimated. Both oils showed low levels of acidity and peroxides, <1.8 mg KOH g-1 and < 1.7 mEq kg-1, respectively, which are good indicators of their preservation status, agreeing with the food regulations. PAO and WAO showed differences among the composition of fatty acids, mainly related to the content of monounsaturated fatty acids (MUFAs), which were 62.5 and 39.5%, respectively, mainly oleic acid. Regarding the polyunsaturated fatty acids (PUFAs), the WAO showed up to 23% of linoleic acid, whereas the PAO exhibited up to 11% of it. These differences reflect on the values of the nutritional functionality indices, atherogenic (AI), thrombogenic (IT), and hypocholesterolemic/hypercholesterolemic ratio (H/H). Both PAO and WAO showed low levels of AI and TI and superior values of H/H than other oilseeds from the literature. These results indicate the nutritional properties of açaí oils regarding a potential cardioprotective effect when included in a regular dietary intake. The thermogravimetric behavior and the evaluation of oxidation status by infrared spectroscopy (FTIR) were also studied. Both açaí oils demonstrated higher thermal stability (with an onset temperature ranging from 344 to 350 °C) and low indications of oxidation status, as no chemical groups related to it were noted in the FTIR spectrum, which agrees with the determined acidity and peroxide content. Moreover, the FTIR analysis unveiled characteristic chemical groups related to fatty acids and triglycerides, agreeing with the literature reports. These findings collectively contribute to a deeper comprehension of the nutritional and functional properties between white and purple açaí oils, offering valuable insights into their potential health, food, and industrial applications.

Thermal oxidation mechanism of palmitic aicd

The oxidation and degradation of fats lead to a decrease in the nutritional value of food and pose safety concerns. Saturated fatty acids also hold a significant position in the field of lipid oxidation. In this study, the oxidation products of methyl palmitate were investigated by using gas chromatography mass spectrometry (GC-MS). Seven monohydroperoxides and 72 secondary oxidation products were detected. Combined with density functional theory (DFT) calculations, the formation mechanisms of oxidation products can be summarized into four stages. The initial stage involved the formation of monohydroperoxides and alkanes, followed by the subsequent stage involving methyl x-oxo(hydroxy)hexadecanoates. The third stage involved the formation of methyl ketones, carboxylic acids, and aldehydes, while the final stage involved lactones. Meanwhile, methyl ketones were the most abundant oxidation product, approximately 25 times more abundant than aldehydes; the calculated results agreed well with the experimental results. The establishment of a comprehensive thermal oxidation mechanism for palmitic acid provided a new foundation for future lipid oxidation analyses.

Synergistic rosemary extract with TBHQ and citric acid improves oxidative stability and shelf life of peanut

Lipid oxidation often accompanies the processing and storage of peanuts, which causes a serious waste of peanut resources. To solve the problem of being prone to oxidation in peanut processing, a ternary complex antioxidant based on rosemary extract (RE) was constructed to investigate its effect on the oxidative and thermal stability of peanuts, and the inhibition of peanut oxidation by compound antioxidants was revealed by dynamic Arrhenius formula and complexation theory. The results showed that there was a synergistic effect between RE and Tert-butyl hydroquinone (TBHQ), and the antioxidant effects of RE and TBHQ were 4.86 and 1.45 times higher when used in combination than when used alone, respectively. In addition, RE-TBHQ-CA (citric acid) effectively inhibited primary and secondary oxidation of peanuts with a shelf life 8.7 times longer than that of control peanuts. This study provides a novel antioxidant compounding idea, which has a positive effect on improving the quality of peanut and other nut products, prolonging the shelf life and reducing the waste of resources. PRACTICAL APPLICATION: Compounding a complex antioxidant that permits its use in peanuts. It was found that rosemary and TBHQ might have synergistic antioxidant effects. Meanwhile, this combination of RE-TBHQ-CA effectively inhibited the oxidation of peanut oils and prolonged the shelf life of peanuts. RE-TBHQ-CA is a highly efficient complex antioxidant that can reduce the amounts of antioxidants added while maintaining high antioxidant efficiency, which may be useful for the future preservation and storage of nut products as it positively affects the quality and shelf life of the product.

Characterization of Lipid Extracts from Different Colors of Peach Palm Fruits-Red, Yellow, Green, and White-Obtained through Ultrasound-Assisted Green Extraction

This study represents a pioneering investigation and comparative analysis of lipid extracts from four different colors of peach palm (Bactris gasipaes Kunt) fruits-red, yellow, green, and white-by employing a green method based on ethanolic ultrasound-assisted extraction. This study examined the extraction yield, physico-chemical-quality attributes, chromatographic profiles (GC), color measurements, total carotenoid content, differential thermogravimetry (TG/DTA), and infrared spectroscopy (FTIR). The obtained lipid extracts displayed a high quality, considering the physico-chemical parameters of the Codex Alimentarius, and a fatty acids profile characterized by unsaturated fatty acids, notably omegas (ω-3, ω-6, and ω-9). The indices of atherogenicity (A.I.), thrombogenicity (I.T.), and hypocholesterolemic and hypercholesterolemic ratios revealed superior outcomes for the red peach palm lipid extract (approximately 0.35, 0.52, and 2.75, respectively), along with higher levels of β-carotene (748.36 µg of β-carotene per 100 g-1 of lipid extract) compared to the yellow, green, and white counterparts. Consequently, this research successfully demonstrates the efficacy of using a green extraction method in preserving the lipid's quality, which can display cardiovascular functionality and thermal stability. These findings underscore the considerable potential of peach palm lipid extract as a valuable raw material for diverse industrial applications across various sectors. The results support its utilization in the production of functional food products and nutraceuticals due to its favorable fatty acid composition, potent antioxidant properties exhibited by its high β-carotene content, and notable cardiovascular functionality indices.

Biodiesel production and characteristics from waste frying oils: sources, challenges, and circular economic perspective

Biodiesel serves as a viable alternative to traditional diesel due to its non-toxicity, biodegradability, and lower environmental footprint. Among the diverse edible and inedible feedstocks, waste frying oil emerges as a promising and affordable feedstock for biodiesel production. Commonly waste frying oils include those derived from palm, corn, sunflower, soybean, rapeseed, and canola. The primary challenge related to biodiesel production technologies is the high production cost, which poses a significant barrier to its widespread adoption. Thus, refining the production techniques is essential to enhance yield, reduce capital expenditure, and curtail raw material expenses. An examination of the research focusing on feedstock availability, production, hurdles, operational expenditures, and future potential is pivotal for identifying the most economically and technically viable solutions. This paper critically reviews such research by exploring feedstock availability, production techniques, challenges, and costs intrinsic to biodiesel synthesis. It also underscores the economic feasibility of biodiesel production, shedding light on the pivotal factors that influence profitability, especially when leveraging waste frying oils. Through an in-depth understanding of these considerations, optimal production and feedstock choices for biodiesel production can be identified. Addressing cost and production bottlenecks could potentially enhance the economic viability of waste frying oil-based biodiesel, thus fostering both environmental sustainability and more extensive adoption of biodiesel as an environmental-friendly fuel in the future.

Mechanisms of the Formation of Nonvolatile and Volatile Oxidation Products from Methyl Linoleic Acid at High Temperatures

The impact of the oxidation of linoleic acid cannot be overlooked in daily food consumption. This study used gas chromatography-mass spectrometry (GC-MS) to identify both nonvolatile oxidation products and volatile oxidation products of methyl linoleic acid at 180 °C and density function theory to investigate oxidation mechanisms. An analysis of nonvolatile oxidation products revealed the presence of three primary oxidation products. The three primary oxidation products were identified as hydroperoxides, peroxide-linked dimers, and heterocyclic compounds in a ratio of 2.70:1:3.69 (mmol/mmol/mmol). The volatile components of secondary oxidation products were found including aldehydes (40.77%), alkanes (19.89%), alcohols (9.02%), furans (6.11%), epoxides (0.46%), and acids (2.50%). DFT calculation proved that the secondary oxidation products mainly came from peroxides (77%). Finally, we look forward to our research contributing positively to lipid autoxidation and human health.

A versatile method to fingerprint and compare the oxidative behaviour of lipids beyond their oxidative stability

In this work we propose the use of isothermal thermogravimetry to evaluate the oxidative stability of a lipid and to evaluate how the glyceride composition affects the entire oxidative process, to quantify the oxidation undertaken by the lipid, and numerically compare the oxidative behaviour of different lipids. The innovative aspect of the present method lies in the acquisition of a prolonged "oxygen uptake" curve (4000-10,000 min) of a lipid under oxygen and in the development of a semi-empirical fitting equation for the experimental data. This provides the induction period (oxidative stability), and allows to evaluate the rate of oxidation, the rate and the magnitude of oxidative degradation, the overall mass loss and the mass of oxygen taken by the lipid upon time. The proposed approach is used to characterize the oxidation of different edible oils with different degrees of unsaturation (linseed oil, sunflower oil, and olive oil) as well as chemically simpler compounds used in the literature to model the autoxidation of vegetable oils and lipids in general: triglycerides (glyceryl trilinolenate, glyceryl trilinoleate and glyceryl trioleate) and methyl esters (methyl linoleate and methyl linolenate). The approach proves very robust and very sensitive to changes in the sample composition.

Brassica Genus Seeds: A Review on Phytochemical Screening and Pharmacological Properties

Traditionally, Brassica species are widely used in traditional medicine, human food, and animal feed. Recently, special attention has been dedicated to Brassica seeds as source of health-promoting phytochemicals. This review provides a summary of recent research on the Brassica seed phytochemistry, bioactivity, dietary importance, and toxicity by screening the major online scientific database sources and papers published in recent decades by Elsevier, Springer, and John Wiley. The search was conducted covering the period from January 1964 to July 2022. Phytochemically, polyphenols, glucosinolates, and their degradation products were the predominant secondary metabolites in seeds. Different extracts and their purified constituents from seeds of Brassica species have been found to possess a wide range of biological properties including antioxidant, anticancer, antimicrobial, anti-inflammatory, antidiabetic, and neuroprotective activities. These valuable functional properties of Brassica seeds are related to their richness in active compounds responsible for the prevention and treatment of various chronic diseases such as obesity, diabetes, cancer, and COVID-19. Currently, the potential properties of Brassica seeds and their components are the main focus of research, but their toxicity and health risks must also be accounted for.

Optimizing Uniaxial Oil Extraction of Bulk Rapeseeds: Spectrophotometric and Chemical Analyses of the Extracted Oil under Pretreatment Temperatures and Heating Intervals

Optimizing the operating factors in edible oil extraction requires a statistical technique such as a response surface methodology for evaluating their effects on the responses. The examined input factors in this study were the diameter of pressing vessel, VD (60, 80, and 100 mm), temperature, TPR (40, 60, and 80 °C), and heating time, HTM (30, 60 and 90 min). The combination of these factors generated 17 experimental runs where the mass of oil, oil yield, oil extraction efficiency, and deformation energy were calculated. Based on the response surface regression analysis, the combination of the optimized factors was VD: 100 (+1) mm; TPR: 80 °C (+1) and HTM: 60 (0) min); VD: 60 (–1) mm; TPR: 80 °C (+1) and HTM: 75 (+0.5) min and VD: 100 (+1) mm; TPR: 80 °C (+1) and HTM: 90 (+1). The absorbance and transmittance values significantly (p < 0.05) correlated with the wavelength and temperature, but they did not correlate significantly (p > 0.05) with heating time. The peroxide value did not correlate significantly with temperature, however, it correlated significantly with heating time. Neither the acid value nor the free fatty acid value correlated with both temperature and heating time. The findings of the present study are part of our continuing research on oilseeds’ processing optimization parameters.

The conversion of linoleic acid into hydroxytetrahydrofuran-structured bio-lubricant

In this work, a new structured linoleic-based hydroxytetrahydrofuran (HTHF) ester lubricant with excellent properties was developed. A synthesis route through regioselective enzymatic hydration was established, combining highly selective epoxidation with an intramolecular epoxide ring-opening reaction. The results proved that the enzymatic-chemical method is an alternative strategy for the conversion of linoleic acid into bio-lubricants. LiBr was revealed as an efficient catalyst (yields of 95.8%, and selectivity of 98.5%, respectively) for the intramolecular epoxide ring-opening reaction. The tribological properties test indicated that the HTHF bio-lubricants exhibited better performance than the commercial mineral oils. Physicochemical investigation further indicated that the product has a good thermal stability, with the T_onset around 300 °C. The kinematic viscosity and viscosity index indicated that the product is suitable to be applied for lubrication. In contrast with previous findings, this HTHF-structured bio-lubricant oil exhibited a superior low pour point (-64 °C) and provided great potential to be utilized in extreme cold working environments.

CO2 supercritical fluid extraction of pulp and nut oils from Terminalia catappa fruits: Thermogravimetric behavior, spectroscopic and fatty acid profiles

The aim of this study was to investigate the attributes of the pulp and nut oils from Terminalia catappa fruits obtained by supercritical fluid extraction (SFE) with pressurized CO₂. The yield, physico-chemical characterization and fatty acid profiles of both oils were assessed based on their acidity and peroxide indices, thermogravimetric behavior, infrared spectroscopic and gas chromatographic analyses. The extraction yields were 7.4% and 61.5% for the pulp and nut from T. catappa, respectively. The pulp and nut oils exhibited low levels of acidity, 3.3 and 1.9 mg KOH g^-1, and peroxides, 3.8 and 1.7 mEq kg^-1, respectively. These values are lower than the maximum recommended levels given by the Codex Alimentarius for virgin oils (4.0 mg KOH g^-1 and 15 mEq Kg^-1, respectively). Unsaturated fatty acids were a major constituent of the oils (58%), of which omegas 3 and 6 were predominant. The infrared spectroscopy of the nut oil showed high intensity bands between 2912 and 716 cm^-1, representative of chemical groups commonly present in unsaturated fatty acids. The pulp oil displayed higher thermal stability than the nut oil, whereby the initial degradation temperatures (T_onset) were 280 °C and 230 °C, respectively. This difference may be related to a greater amount of saturated fatty acids in the pulp oil compared to the nut oil. Thus, both pulp and nut oils displayed good physicochemical properties, which are desirable in diverse industrial sectors.

Comparative Study of the Oxidation Stability of High Oleic Oils and Palm Oil during Thermal Treatment

For the controversy still existed about the oxidation stability of the high oleic oils compared with palm oil (PO), this study was aimed to explore the possible reason causing the controversies. Total polar compounds (TPC) was used to evaluate the oxidation stability of oils. Results showed there exist two kinds of lineal changes about the content of total polar compounds (TPC) in each oil, which were closely linked with the fatty acid composition and the tocochromanols content. The possible influence of the initial quality of oils also should be considered. The TPC of high oleic peanut oil (HOPO), high oleic sunflower oil (HOSO), high oleic rapeseed oil (HORO) and PO increased slowly at the initial period mainly owing to the antioxidation of tocochromanols, then sharply after 24, 48, 36 and 72 h respectively, when tocochromanols in each oil almost reduced below the detection limit. After that, the major factor would be fatty acids, particularly PUFA. It showed that the major tocochromanols in different oils (e.g. α, γ-tocotrienols in PO, α, γ-tocopherols in HORO and HOPO, and α-tocopherols in HOSO), could impose the main effects of inhibiting the TPC generation in the initial thermal treatment. The TPC in HORO significantly increased after 84 hours of heat process, which might be caused by the higher content of the polyunsaturated fatty acids (PUFA) (i.e. C18:2 and C18:3). However, the content of the saturated fatty acid (SFA) did not show statistically significant change during the thermal treatment.

Determination of the Oxidative Stability of Camellia Oils Using a Chemometrics Tool Based on 1H NMR Spectra and α-Tocopherol Content

This study, for the first time, predicts oxidative stability in camellia oils by partial least squares (PLS) built with proton nuclear magnetic resonance (¹H NMR) and α-tocopherol content. The prediction models were established by the PLS method. Outlier detection, latent variables optimization, data pretreatment, and important variables selection were applied for models optimization. All the developed models exhibited good performance as indicated by R² > 0.895 and root mean square error of estimation and root mean square error of prediction less than 0.322 and 0.307. For verification of the contribution of ¹H NMR spectra and α-tocopherol for prediction performance, a PLS model with fatty acids composition instead of ¹H NMR spectra and one with only ¹H NMR spectra as input variables were developed, respectively. The results showed that the model based on ¹H NMR data was more accurate and precise than that based on fatty acid composition data. And the performance of the models was significantly degraded without α-tocopherol as input variables.

Assessing the Potentiality of Animal Fat Based-Bio Phase Change Materials (PCM) for Building Applications: An Innovative Multipurpose Thermal Investigation

In recent years, the implementation of novel solutions aimed at improving thermal energy storage (TES) capability to both energy technologies and building-integrated systems has gained increasing attention. In particular, the application of phase change materials (PCM) is currently gathering worldwide acknowledgment. In this work, the potential of animal fat as a novel bio-based PCM having transition temperature around the ambient temperature is assessed by means of thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), and extensive temperature monitoring. Results from the TGA showed the differential degradation of the main components of the animal fat during the heating phase, where three different decomposition steps could be noticed. The thermal monitoring and the DSC analysis demonstrated the promising thermal performance of the material, which showed an interesting double transition range globally associated to a melting enthalpy of about 28.94 kJ·kg - 1 . The obtained results demonstrate the promising thermophysical properties of the animal fat blend, which can be considered as a low-cost, biocompatible PCM, particularly with potential application in passive building envelope applications for a wide range of temperature boundary conditions.

Determination of the Thermal Oxidation Stability and the Kinetic Parameters of Commercial Extra Virgin Olive Oils from Different Varieties

The use of olive oil with cooking purposes, as final seasoning or within cooked foods is increasing worldwide due to its numerous nutritional and health benefits. These attributes are mainly determined by olive oil chemical composition, which can be altered after thermal processing, oxidation processes, or incorrect practices. For this reason, and due to the numerous factors which have influence in olive oil quality, the correct chemical characterization is highly relevant. In this study, fatty acid composition of four extra virgin olive oil (EVOO) varieties was studied. The major fatty acid (FA) determined was oleic acid (77.1% on average), followed by palmitic (11.5% on average). In addition, thermal oxidation behaviour of the four EVOO samples was studied as an indicator of their quality and stability during thermal processing. This was performed through differential scanning calorimetry (DSC) from a temperature of 40°C at six different heating rates in the range of 0.5–10°C min−1. DSC records showed the same pattern and a small shoulder in the thermo-oxidation peak was present for all samples and all heating rates. The presence of initial and final oxidation products (by monitoring K232 and K270 values, respectively) was discarded according to the International Olive Council method.