Autoxidative Stability Research Articles

Applying Material Science Principles to Chemical Stability: Modelling Solid State Autoxidation in Mifepristone Containing Different Degrees of Crystal Disorder

Ball-milling and harsh manufacturing processes often generate crystal disorder which have practical implications on the physical and chemical stabilities of solid drugs during subsequent storage, transport, and handling. The impact of the physical state of solid drugs, containing different degrees/levels of crystal disorder, on their autoxidative stability under storage has not been widely investigated. This study investigates the impact of differing degrees of crystal disorder on the autoxidation of Mifepristone (MFP) to develop a predictive (semi-empirical) stability model. Crystalline MFP was subjected to different durations of ambient ball milling, and the resulting disorder/ amorphous content was quantified using a partial least square (PLS) regression model based on Raman spectroscopy data. Samples of MFP milled to generate varying levels of disorder were subjected to a range of (accelerated) stability conditions, and periodically sampled to examine their recrystallization and degradation extents. Crystallinity was monitored by Raman spectroscopy, and the degradation was evaluated by liquid chromatography. The analyses of milled samples demonstrated a competition between recrystallization and degradation via autoxidation of MFP, to different extents depending on stability conditions/exposure time. The degradation kinetics were analyzed by accounting for the preceding amorphous content, and fitted with a diffusion model. An extended Arrhenius equation was used to predict the degradation of stored samples under long-term (25°C/60% RH) and accelerated (40°C/75% RH, 50°C/75% RH) stability conditions. This study highlights the utility of such a predictive stability model for identifying the autoxidative instability in non-crystalline/partially crystalline MFP, owing to the degradation of the amorphous phases. This study is particularly useful for identifying drug-product instability by leveraging the concept of material sciences.

Photo-Oxidative Stability of Aqueous Model Systems Enriched with Omega-3 Long-Chain Polyunsaturated Fatty Acid-Rich Microalgae as Compared to Autoxidative Stability.

Several species of microalgae are promising as an alternative source of omega-3 long-chain polyunsaturated fatty acids (n-3 LC-PUFA). Photoautotrophic species show the greatest potential, since incorporating them into food products leads to oxidatively stable products; however, the presence of photosensitizers could reduce the shelf-life due to the appearance of photo-oxidation on exposure to light. This study investigated the oxidative impact of illumination for aqueous model suspensions enriched with Phaeodactylum (phototrophic microalgae─containing potential photosensitizers) and Schizochytrium (heterotrophic microalgae─lacking photosensitizers) during storage for 28 days at 37 °C. Primary (peroxide value) and secondary (volatiles with gas chromatography (GC)-mass spectrometry) oxidation products, n-3 LC-PUFA content (GC), and pigments (high-pressure liquid chromatography) were assessed. The results showed that photo-oxidation did not cause oxidative instability for Phaeodactylum samples compared with strong autoxidation in Schizochytrium samples. For the Phaeodactylum-enriched suspensions, only minimal photo-oxidation could be detected and the n-3 LC-PUFA content remained stable throughout storage regardless of illumination.

Assessment of ethanol autoxidation as a drop-in kerosene and surrogates blend with a new modelling approach

Bioethanol has been considered as a more sustainable alternative for fossil fuels, and it has been used as a drop-in fuel mixture. In this paper, the autoxidation properties of real kerosene as well as single, binary and ternary surrogates with the presence of ethanol are investigated for the first time. A simplified python code is proposed to predict the pressure drop of the PetroOXY method that was used for assessing the fuel autoxidation properties. The experimental results show that the addition of an ethanol concentration reduces the induction period of real kerosene while increasing that of surrogate mixtures. Also, the maximum pressure during the PetroOXY test increases with the increase of ethanol concentration. The model is able to predict the induction period of ethanol accurately by employing an automated reaction mechanism generator. A strategy to increase the autoxidation stability of ethanol by adding 1 g/L antioxidant has been evaluated. The efficiency of the antioxidants for ethanol is in the following order: PY > Decalin > DTBP > Tetralin > BHT > MTBP > BHA > TBHQ > PG.

Autoxidation and photooxidation of triacylglycerols containing conjugated linoleic acids

Soybean, cottonseed, and corn oils were hydrogenated to obtain triacyglycerols containing conjugated linoleic acids. The oxidative stability of soybean oil, cottonseed oil, and corn oil was less with CLA than without CLA during autoxidation. However, the autoxidative stability of oils increased as the CLA content increased. During photooxidation of oils, the oxidative stability of oils was higher with CLA than without CLA, and the stability of oils increased as the CLA content increased. The mechanisms of autoxidation and photooxidation of oils were probably due to the contents and anti- and prooxidant activities of individual conjugated linoleic acids in bulk oil, and minor compounds present in oils.

Effects of catechin and α-tocopherol addition on the autoxidative stability of diacylglycerol oil derived from an olive oil and perilla oil mixture

The effects of tea catechin and α-tocopherol addition (1 mM) on the oxidative stability of oleic and linolenic acid-rich diacylglycerol (DAG) oil derived from an extra virgin olive oil and perilla oil mixture (6:4, w/w) were evaluated. Oil was oxidized at 50°C for 10 days, after which oxidation was evaluated based on headspace oxygen consumption and peroxide values (POV). The polyphenol and tocopherol contents were also monitored. Addition of catechin did not affect the oxygen consumption or POV of DAG oil, whereas α-tocopherol acted as a prooxidant. Addition of antioxidants had no significant (p>0.05) effect on the fatty acid composition of the oil. Degradation of γ-tocopherol during oil oxidation was inhibited by addition of α-tocopherol, and addition of antioxidants inhibited polyphenol degradation. The autoxidative stability of DAG oil can be improved using polar rather than non-polar antioxidants.

Mass spectrometry to evaluate the effect of the ripening process on phenols of virgin olive oils

SummaryA global approach has been developed to study the influence of ripening of olive fruits on the phenolic fraction present in virgin olive oil from different genotypes of olives. For this purpose, a non‐targeted method based on the analysis of phenolic extracts by MS in high resolution mode was applied. The phenolic profiles obtained by liquid chromatography ‐ quadrupole‐quadrupole‐time‐of‐flight (LC‐QqTOF) were compared by statistical multivariate analysis tools such as principal component analysis and heat correlation maps. In overall terms, discrimination was only observed for specific crop dates and ripening index values, which should be ascribed to a strong influence of the genotype. The ripening process of each genotype was also studied to demonstrate the variation of phenolic profile in relation to the ripening index. This study was also extended to a panel of representative phenols appreciated by their health and nutritional properties. The application of omics technologies to plant breeding programs could be considered as one of the main pillars on which improvement of products quality can be supported.Practical applications: Olive oil phenols are of a great interest since they contribute to autoxidation stability, health properties, and organoleptic characteristics of virgin olive oil. These phenols are considered a key to assess virgin olive oil quality. This study is focused on the effect of the ripening process on the phenolic fraction from a metabolomics point of view. This advanced omics technology (foodomics) applied to plant breeding programs can be one of the pillars to improve products quality.

Effect of Droplet Size on Autoxidation Rates of Methyl Linoleate and ^|^alpha;-Linolenate in an Oil-in-Water Emulsion

Methyl linoleate and α-linolenate were used as representative n-6 and n-3 polyunsaturated fatty acid esters, respectively, to examine the effect of oil droplet size on autoxidative stability in oil-in-water systems. The emulsions, which were prepared via membrane emulsification and had a mean oil droplet size of approximately 1-30 μm, and had a stable size during the autoxidation of each substrate at 55°C. The autoxidation of methyl linoleate did not depend on oil droplet size during the entire process and that of methyl α-linolenate was independent of oil droplet size during the first half of the autoxidation process. However, the autoxidation rate of methyl α-linolenate proceeded faster in the emulsion with smaller oil droplet size during the last half of the autoxidation process.

Predicting Autoxidation Stability of Ether- and Amide-Based Electrolyte Solvents for Li–Air Batteries

Finding suitable solvents remains one of the most elusive challenges in rechargeable, nonaqueous Li-air battery technology. Although ether and amides are identified as stable classes of aprotic solvents against nucleophilic attack by superoxide, many of them are prone to autoxidation under oxygen atmosphere. In this work, we use density functional theory calculations coupled with an implicit solvent model to investigate the autoxidative stability of ether- and N,N-dialkylamide-based solvents. The change in the activation free energy for the C-H bond cleavage by O(2) is consistent with the extent of peroxide production for each class of solvent. Conversely, the thermodynamic stability alone is not sufficient to account for the observed variation in solvent reactivity toward O(2). A detailed understanding of the factors influencing the autoxidative stability provides several strategies for designing molecules with enhanced air/O(2) stability, comparable or superior to that of structurally related hydrocarbons. The mechanism of superoxide-mediated oxidation of hydroperoxides derived from ethers and amides is presented. The degradation mechanism accounts for the primary decomposition products (esters and carboxylates) observed in the Li-air battery with ether-based electrolytes. The identification of solvents having resistance to autoxidation is critical for the development of rechargeable Li-air batteries with long cycle life.

Study of α-, γ-, and δ-tocopherols in the oxidative stability of lard

Effects of α-, γ-, and δ-tocopherols at 0, 50, 100, 250, 500, and 1,000 ppm on the oxidative stability of lard during storage in the dark at 55°C for 7 days were studied by determining headspace oxygen content and peroxide value. The headspace oxygen content of the lard without tocopherol addition decreased from 21.1 to 14.4% and the peroxide value increased from 2.5 to 15.4 meq/kg lard for 7 days. The headspace oxygen depletion and the peroxide value of lard decreased by the addition of α-tocopherol at 50 ppm, but significantly increased at 250, 500, or 1,000 ppm. As the concentration of γ-tocopherol or δ-tocopherol increased, the headspace oxygen depletion and the peroxide value decreased. α-Tocopherol at 250 ppm acted as a prooxidant in the autoxidation of lard. The concentrations of γ- or δ-tocopherol to be applied to improve the autoxidative stability of lard may be 100–250 ppm.

Stability of tocopherols and lutein in oil extracted from roasted or unroasted mustard seeds during the oil oxidation in the dark

This study compared stabilities of tocopherols and lutein in oil extracted from roasted mustard seeds (RMSO) with those in oil from unroasted seeds (URMSO) during oil oxidation at 60°C in the dark for 12 days. Tocopherols and lutein were determined by high performance liquid chromatography, and the oil oxidation was monitored with conjugated dienoic acid (CDA) content and fatty acid composition by gas chromatography. The rate of CDA increase was lower in RMSO (0.038%/day) than in URMSO (0.047%/day) during 12-day oxidation in the dark, with little change in fatty acid composition in both oils. Tocopherols and lutein were more abundant in RMSO, initially 465.38 and 100.55 μg/g, respectively, than in URMSO, and their stability was higher in RMSO (−4.63 and −5.94%/day of degradation in tocopherols and lutein, respectively) than in URMSO during 12-day oxidation of oil, both of which contributed to higher autoxidative stability of RMSO than URMSO.

Ligand changes in ferric species of the giant extracellular hemoglobin ofGlossoscolex paulistusas function of pH: correlations between redox, spectroscopic and oligomeric properties and general implications with different hemoproteins

The present review is focused on the relationship between oligomeric and heme properties of HbGp, emphasizing the characteristics that can be generalized to other hemoproteins. This study represents the state-of-the-art with respect to the approaches for investigating giant extracellular hemoglobins as well as the correlation between oligomeric assembly alterations and their consequent changes in the first coordination sphere. A wide introduction focused on the properties of this hemoglobin is developed. Indeed, this hemoprotein is considered an interesting prototype of blood substitute and biosensor due to its peculiar properties, such as resistance to autoxidation and oligomeric stability. Previous studies by our group employing UV-vis, EPR and CD spectroscopies have been revised in a complete approach, in agreement with recent and relevant data from the literature. In fact, a consistent and inter-related spectroscopic study is described propitiating a wide assignment of "fingerprint" peaks found in the techniques evaluated in this paper. This review furnishes physicochemical information regarding the identification of ferric heme species of hemoproteins and metallic complexes through their spectroscopic bands. This effort at the attribution of UV-vis, EPR and CD peaks is not restricted to HbGp, and includes a comparative analysis of several hemoproteins involving relevant implications regarding several types of iron-porphyrin systems.

Extraction of Lignan Compounds from Roasted Sesame Oil and their Effects on the Autoxidation of Methyl Linoleate

ABSTRACT: Lignan compounds were extracted from roasted sesame oil and their effects on the autoxidation of methyl linoleate (ML) were studied. Lignan compounds extracted from roasted sesame oil, sesamol, sesamin, and sesamolin, were added to ML, which was then oxidized at 60 oC for 18 h in the dark. Alpha‐tocopherol was separately added to ML for a reference antioxidant. Degree of ML oxidation was monitored by conjugated dienoic acid (CDA) contents and p‐anisidine value (PAV) by AOCS methods, and ML retention by gas chromatography. CDA contents and PAV of samples increased with the oxidation time at 60 oC in the dark, and ML decreased. Sesamol‐, sesamin‐, or sesamolin‐added samples showed lower CDA contents, PAV, and ML loss than the samples without lignans during oxidation in the dark, which indicated that lignan compounds lowered the ML autoxidation. The antioxidant activity of sesamol was significantly higher (P < 0.05) than that of sesamin, sesamolin, or α‐tocopherol. Lignan compounds added to ML were degraded during the autoxidation of ML, and the degradation rate was higher in sesamol‐ than in sesamin‐, or sesamolin‐added ML, but was lower than in tocopherol‐added samples. As the lignan compounds concentration in ML increased, the degradation rate of lignans decreased, and the inhibition of the ML autoxidation by lignan compounds increased. The results strongly suggested that the autoxidative stability of ML could be improved by the addition of sesamol, sesamin, or sesamolin extracted from the roasted sesame oil.

Effects of the cold percolation system on the quality of virgin olive oil

The effects of the cold percolation system on the quality of virgin olive oil from two different Italian cultivars (Coratina and Oliarola) were determined. The quality was also compared with that of oil extracted with the current centrifugation system using a two-phases decanter. Tests were performed in an industrial oil mill equipped with the two extraction systems. The oils extracted with cold percolation system showed, in all cases, lower free acidity, peroxide value, and ultraviolet (UV) absorption (K232 and K270) and higher polyphenol contents in comparison to oils obtained by two-phases centrifugation. These results were confirmed by the autoxidation stability of the oils examined.

Análisis mediante HPLC de la fracción fenólica del aceite de oliva virgen de la variedad Arbequina. Relación con la medida del amargor K225 y la estabilidad

Phenolic compounds have a high importance because of their effect on shelf life and sensorial characteristics of virgin olive oil. In this paper, the phenolic fraction of Arbequina virgin olive oils has been characterized by HPLC. Bitterness index K225, total phenols and autoxidation stability have been evaluated for olive oil samples. From the phenolic compounds separated using HPLC method, one of then (tr: 34,49 min) was close correlated both with bitterness K225 and oil stability Rancimat at 98oC. The regression coefficients, with high significance p<0,001, were r: 0.974 and r: 0.918 respectively. Phenolic compound responsible of bitterness K225 and oil stability has been found for the Arbequina virgin olive oils.

Elaboración del aceite de oliva virgen mediante sistema continuo en dos fases. Influencia de diferentes variables del proceso en algunos parámetros relacionados con la calidad del aceite

The introduction of new technology for industrial extraction of olive oil requires a knowledge of how this could affect certain oil parameters in regulation of the extraction process. The oil's total polyphenols content, K225 and autoxidation stability were related with variations in temperature, kneading time, paste injection flow rate and oil washing in vertical centrifuges in a two-phase decanter without addition of water to the olive paste. Kneading the olive paste at low temperature, extended kneading at low paste injection rates, oil washing with hot water and high water:oil ratio, yielded oil of low stability, low polyphenols content and low bitterness.

Comparison of oxidative stability of high‐ and normal‐oleic peanut oils

A peanut breeding line with high‐oleic acid and an isogenic sister line with normal fatty acid composition were obtained. Oil was extracted with dichloromethane and processed in the laboratory by alkali neutralization and bleaching. Fatty acid compositions were determined by gas chromatography and application of theoretical response factors. Oils were extracted and processed in duplicate. The oxidative stability of the oils was measured by the Schall oven test (80°C), active oxygen method (AOM) (112°C) and by comparison of oxidation rates on thin‐layer chromatography‐flame ionization detector (TLC‐FID) rods (100°C). Fatty acid analysis indicated that the high‐oleic line had 75.6 and 4.7% oleic and linoleic acids, respectively, compared to 56.1 and 24.2% for the normal line. The induction times for the Schall test were 682 and 47 h for high‐ and normal‐oleic oils (P&lt;0.01). The AOM induction times were 69 and 7.3 h for high and normal oils, respectively (P&lt;0.01). The times to reach 50% loss in triglyceride area on TLC‐FID were 847 and 247 min for high‐oleic compared to normal‐oleic oils (P&lt;0.01). The results indicate that high‐oleic peanut oil has much greater autoxidation stability as compared to normal oil.

Simple and hydrolyzable phenolic compounds in virgin olive oil. 1. Their extraction, separation, and quantitative and semiquantitative evaluation by HPLC

Phenolic compounds have a fundamental importance in the nutritional and sensory characteristics of virgin olive oil. Problems regarding their qualitative and quantitative evaluation have not been completely solved; hence, in this paper the extractive and HPLC methods of analysis are examined and some modifications are presented. By means of these techniques, elenolic acid and four unknown compounds having phenolic behavior were separated from virgin olive oil. Four of them were correlated with total phenols evaluated by means of the Folin-Ciocalteu reagent, and two of them were correlated with olive oil autoxidation stability

Influence of triglyceride molecular species on autoxidation.

The autoxidative stability of triglyceride molecular species was analyzed by determining the residual molecular species after incubating synthesized triglycerides (TGs), interesterified TGs and soybean oil TGs, respectively. The autoxidative stability of each molecular species of TG depends on the degree of unsaturation of TGs and the length of the saturated acyl chain present in glycerides. Thirteen types of soybean oil TG molecular species were isolated by high performance liquid chromatography. Among them, the TG groups most resistant to autoxidation were 2-oleoyl-1(3)-stearoyl-3(1)-palmitin, 1,3-dipalmitoyl-2-olein, 2-oleoyl-1(3)-oleoyl-3(1)-stearin and 2-oleoyl-1(3)-oleoyl-3(1)-palmitin.

Influence of interesterification on the autoxidative stability of vegetable oils.

Influence of interesterification on the autoxidative stability of vegetable oils.

Influence of Interesterification on the Autoxidative Stability of Vegetable Oils

Influence of Interesterification on the Autoxidative Stability of Vegetable Oils Get access Dong Ki Park, Dong Ki Park Research Institute for Food Science, Kyoto University, Uji Kyoto, 611, Japan Search for other works by this author on: Oxford Academic Google Scholar Junji Terao, Junji Terao Research Institute for Food Science, Kyoto University, Uji Kyoto, 611, Japan Search for other works by this author on: Oxford Academic Google Scholar Seturo Matsushita Seturo Matsushita Research Institute for Food Science, Kyoto University, Uji Kyoto, 611, Japan Search for other works by this author on: Oxford Academic Google Scholar Agricultural and Biological Chemistry, Volume 47, Issue 1, 1 January 1983, Pages 121–123, https://doi.org/10.1080/00021369.1983.10865593 Published: 01 January 1983 Article history Received: 25 March 1982 Published: 01 January 1983