Prediction of Oxidation Stability of Biodiesel Derived from Waste and Refined Vegetable Oils by Statistical Approaches

The oxidation stability (OX) of the biodiesel is an essential parameter mainly during storage, which reduces the quality of the biodiesel, thus affecting the engine performance. Moreover, many factors affect oxidation stability. Therefore, determining the most significant parameter is essential for achieving accurate predictions. In this paper, an empirical equation (Poisson Regression Model (PRM)), machine learning models (Multilayer Feed-Forward Neural Network (MFFNN), Cascade Feed-forward Neural Network (CFNN), Radial Basis Neural Network (RBFNN), and Elman neural network (ENN)) with various combinations of input parameters are utilized and employed to identify the most relevant parameters for prediction of the oxidation stability of biodiesel. This study measured the physicochemical properties of 39 samples of waste frying methyl ester and their blends with various percentages of palm biodiesel and refined canola biodiesel. To this aim, 14 parameters including concentration amount of WFME (X1), PME (X2), and RCME (X3) in the mixture, kinematic viscosity (KV) at 40 °C, density at 15 °C (D), cloud point (CP), pour point (PP), the estimation value of the sum of the saturated (∑SFAMs), monounsaturated (∑MUFAMs), polyunsaturated (∑PUFAMs), degree of unsaturation (DU), long-chain saturated factor (LCSF), very-long-chain fatty acid (VLCFA), and ratio (∑MUFAMs+∑PUFAMs∑SFAMs) fatty acid composition were considered. The results demonstrated that the RBFNN model with the combination of X1, X2, X3, ∑SFAMs, ∑MUFAMs, ∑PUFAMs. VLCFA, DU, LCSF, ∑MUFAMs+∑PUFAMs∑SFAMs, KV, and D has the lowest value of root mean squared error and mean absolute error. In the end, the results demonstrated that the RBFNN model performed well and presented high accuracy in estimating the value of OX for the biodiesel samples compared to PRM, MFFNN, CFNN, and ENN.

Comparison of a Rapid Light-Induced and Forced Test to Study the Oxidative Stability of White Wines

The oxidation processes of white wines can occur during storage and commercialization due to several factors, and these can negatively affect the color, aroma, and quality of the wine. Wineries should have faster and simpler methods that provide valuable information on oxidation stability of wines and allow fast decision-making procedures, able to trigger suitable technological interventions. Using a portable prototype instrument for light irradiations at different wavelengths and times was considered and evaluated on sensorial, spectrophotometric, and colorimetric parameters of white wines. The sensorial analysis revealed that white and light blue were the most significant, after only 1 h of irradiation. The experimental results showed that hydrogen peroxide could enhance the effect of light treatment, allowing a contemporary evaluation of the oxidation stability of wine against light and chemical stresses. As expected, a good correlation (R2 > 0.89) between optical density at 420 nm and b* parameter was highlighted. The synergic effect of light and H2O2 was also studied on the hydrolyzable and condensed tannins’ additions to white wine. The proposed methodology could be used to evaluate the oxidative stability of white wines, but also to evaluate the effect of some oenological adjuvants on wine stability.

Multifaceted functionality of L-arginine in modulating the emulsifying properties of pea protein isolate and the oxidation stability of its emulsions

The effects of L-arginine (Arg) at different concentrations (0%, 0.05%, 0.1%, 0.2%, 0.5% and 1.0%) on the antioxidant activity, structure and emulsifying properties of pea protein isolate (PPI) were explored....

A Comparison of Lipid Contents in Different Types of Peanut Cultivars Using UPLC-Q-TOF-MS-Based Lipidomic Study

Peanuts are a rich dietary source of lipids, which are essential for human health. In this study, the lipid contents of 13 peanut cultivars were analyzed using UPLC-Q-TOF-MS and GC–MS. The OXITEST reactor was used to test their lipid oxidation stabilities. A total of 27 subclasses, 229 individual lipids were detected. The combined analysis of lipid and oxidation stability showed that lipid unsaturation was inversely correlated with oxidation stability. Moreover, lipid profiles differed significantly among the different peanut cultivars. A total of 11 lipid molecules (TG 18:2/18:2/18:2, TG 24:0/18:2/18:3, TG 20:5/14:1/18:2, TG 18:2/14:1/18:2, PE 17:0/18:2, BisMePA 18:2/18:2, PG 38:5, PMe 18:1/18:1, PC 18:1/18:1, MGDG 18:1/18:1, TG 10:0/10:1/18:1) might be employed as possible indicators to identify high oleic acid (OA) and non-high OA peanut cultivars, based on the PLS-DA result of lipid molecules with a VIP value greater than 2. This comprehensive analysis will help in the rational selection and application of peanut cultivars.

Polyunsaturated Fatty Acid Fractionation from Crude Palm Oil (CPO)

Biodiesel is a fuel derived from vegetable oil. One of the vegetable oils that can be used in the manufacture of biodiesel is Crude Palm Oil (CPO). High-quality biodiesel must have a low iodine number and a high oxidation stability. This can be achieved if CPO does not contain polyunsaturated fatty acids (PUFA). It follows that in order to produce high-quality biodiesel, palm oil that contains high saturated fatty acids but that does not contain PUFA is needed. Therefore, it is necessary to fractionate PUFA with saturated fatty acids (SFA) and monounsaturated fatty acids (MUFA). The purpose of this study was to separate PUFA in the form of linoleic acid from CPO and to determine the best conditions in the separation process to produce fatty acids with low iodine numbers. Fractionation was carried out at temperatures of 30 °C and 35 °C, with an extraction time of 3 h and 4 h, and with ratios of CPO and solvent of 1:2 and 1:3 (v/v). The solvents used were n-heptane and DMSO (dimethyl sulfoxide). The results showed that linoleic acid could be separated from CPO using the fractionation method with the best conditions at a temperature of 35 °C, an extraction time of 4 h, a ratio of CPO and solvent of 1:3, an iodine number of 40.78766, and an oxidation stability of 19.03593 h. GC-MS analysis proved that the fractionated CPO did not contain linoleic acid. The lower the iodine number was, the higher the oxidation stability was.

Improved Oxidation Stability of Camellia Oil-in-Water Emulsions Stabilized by the Mixed Monolayer of Soy Protein Isolate/Bamboo Shoot Protein Complexes

The complex of soy protein isolate (SPI)/bamboo shoot protein concentrate (BPC) was developed to stabilize camellia oil-in-water (O/W) emulsions. The surface hydrophobicity of the BPC/SPI complex driven by hydrogen bonds and electrostatic attractions was improved. With the increasing ratio of BPC in the complex, a tighter network layer structure of the complex was formed due to the rearrangement of proteins, and the emulsions showed a progressive enhancement in the gel-like structures. At the SPI/BPC ratio of 2:1, the emulsions had smaller droplet size and lower creaming index of 230 nm and 30%, and the emulsifying activity and stability indices of the emulsions were 803.72 min and 11.85 g/m2, respectively, indicating a better emulsifying activity and stability of emulsions. Meanwhile, the emulsions stabilized by the complex at the ratio of 2:1 showed better storage and antioxidant stability. These findings are expected to develop the application of bamboo shoots in emulsion-based food products such as mayonnaise, salad dressings, and sauces.

Thermal oxidation stability of lubricating greases – can a rapid small-scale method replace the classical method?

The article presents the results of tests of the oxidation resistance of 26 samples of selected lubricating greases available on the market. Various types of lubricant samples (according to the type of thickener), produced with oils of different chemical nature and viscosity, were tested. The basic parameters of the greases were determined: the worked penetration and the dropping point. Two different test methods were used to determine the thermal oxidation stability: the classical oxidation method according to PN-C-04143 and the rapid small-scale test method according to ASTM D 8206. The method of determining the correlation between these methods was presented. A correlation was found between the two methods of testing the resistance to oxidation, which can be roughly described using the exponential dependence. For the quick method, better compliance with the classical method was obtained at 140°C than at 160°C, which is confirmed by the determination coefficients determined by the ranking method. Based on the results of the quick method, using the determined exponential dependency, the results of the classical method can be estimated. However, the determined correlation between the PN-C-04143 and ASTM D 8206 methods is insufficient to use these methods interchangeably.