Supercritical Fluid Extraction of Phenolic Compounds from Mango (Mangifera indica L.) Seed Kernels and their Application as an Antioxidant in an Edible Oil

Phenolic compounds from mango (M. indica) seed kernels (MSK) var. Sugar were obtained using supercritical CO2 and EtOH as an extraction solvent. For this purpose, a central composite design was carried out to evaluate the effect of extraction pressure (11–21 MPa), temperature (40–60 °C), and co-solvent contribution (5–15% w/w EtOH) on (i) extraction yield, (ii) oxidative stability (OS) of sunflower edible oil (SEO) with added extract using the Rancimat method, (iii) total phenolics content, (iv) total flavonoids content, and (v) DPPH radical assay. The most influential variable of the supercritical fluid extraction (SFE) process was the concentration of the co-solvent. The best OS of SEO was reached with the extract obtained at 21.0 MPa, 60 °C and 15% EtOH. Under these conditions, the extract increased the OS of SEO by up to 6.1 ± 0.2 h (OS of SEO without antioxidant, Control, was 3.5 h). The composition of the extract influenced the oxidative stability of the sunflower edible oil. By SFE it was possible to obtain extracts from mango seed kernels (MSK) var. Sugar that transfer OS to the SEO. These promissory extracts could be applied to foods and other products.

A Deep Insight in the Antioxidant Property of Carnosic Acid: From Computational Study to Experimental Analysis

Since the deep cause for the anti-oxidation of carnosic acid (CA) against oleic acid (OA) remains unclear, we focused on exploring the CA inhibition mechanism via a combined experimental and computational study. Atomic charge, total molecular energy, phenolic hydroxyl bond dissociation enthalpy (BDE), the highest occupied molecular orbital (HOMO), and the lowest unoccupied orbital (LUMO) energy were first discussed by the B3LYP/6-31G (d,p) level, a density functional method. A one-step hydrogen atom transfer (HAT) was proposed for the anti-oxidation of CA towards OA, and the Rancimat method was carried out for analyzing the thermal oxidation stability. The results indicate that the two phenolic hydroxyl groups located at C7(O15) and C8(O18) of CA exert the highest activity, and the chemical reaction heat is minimal when HAT occurs. Consequently, the activity of C7(O15) (303.27 kJ/mol) is slightly lower than that of C8(O18) (295.63 kJ/mol), while the dissociation enthalpy of phenol hydroxyl groups is much lower than those of α-CH2 bond of OA (C8, 353.92 kJ/mol; C11, 353.72 kJ/mol). Rancimat method and non-isothermal differential scanning calorimetry (DSC) demonstrate that CA outcompetes tertiary butylhydroquinone (TBHQ), a synthetic food grade antioxidant, both in prolonging the oxidation induction period and reducing the reaction rate of OA. The Ea (apparent activation energies of reaction) of OA, TBHQ + OA, and CA + OA were 50.59, 57.32 and 66.29 kJ/mol, revealing that CA could improve the Ea and thermal oxidation stability of OA.

Relationship between Antioxidant Components and Oxidative Stability of Peanut Oils as Affected by Roasting Temperatures

The study sought to investigate the effect of roasting temperatures on antioxidant components and oxidative stability of peanut oils. The total phenolic content, total flavonoid content, α–tocopherol content, and phytosterol content in peanut oils was influenced by roasting at temperatures of 120 °C, 140 °C, and 160 °C, while those roasting temperatures had no effect on the fatty acid profile and γ–tocopherol content of peanut oils. Roasting promotes the quality of peanut oil aroma via the Maillard reaction, particularly when it is derived from N–heterocyclic compounds (such as pyrazine and pyrrole). The oxidative stability of peanut oils was investigated using the Rancimat method, and the results show that there is a linear relationship between roasting and natural logarithm of the induction period (R2: 0.959~0.998). This was determined based on the Arrhenius equation, which indicated the activation energy (Ea) was in the range of 82.08~108.61 kJ/mol. In principal component analysis (PCA) analysis, the antioxidant stability of the increase levels of phenols released in the peanut oils was found to rise with the increment of roasting temperatures. The data obtained in this study should be confirmed as the nutritional benefits of peanut oils that will be most appealing to consumers.

Impact of plum processing on the quality and oxidative stability of cold-pressed kernel oil

Plum kernels of the “Čačanska rodna” variety, by-products from plum brandy production, were collected before and after fermentation and distillation, and used for cold-pressed oil production. Fatty acid and tocopherol contents were determined by capillary GC and HPLC, while the oxidation stability of the resulting cold-pressed oils was tested by the Rancimat method. The results showed that oleic fatty acid was dominant in the oil samples with a content of 56.6 to 61.8%, regardless of the plum kernels’ origin. The fermentation and distillation processes had a pronounced effect on the tocopherol content and oxidative stability of the resulting kernel oils. Tocopherol contents were 61.8 mg·100g-1, 87.4 mg·100g-1, 79.6 mg·100g-1 of oil, while the induction periods were 38.7, 44.4 and 33.6 hours for samples before fermentation, after fermentation and distillation, respectively. Based on the results, it could be concluded that the fermentation process increased the content of tocopherols in kernel oil whereas the high temperature during the distillation process adversely affected the tocopherol content and oxidative stability of the obtained kernel oil.

Efficiency of different additives in improvement of oxidation stability of fatty acid methyl esters with different properties

This study evaluates six formulations in improving oxidation stability of different fatty acid methyl esters (MEs). Two MEs differed in the unsaturation levels as they were synthesized from different feedstocks: a blend of soybean and sunflower oils (SoSuME), and waste cooking oil (WCOME); they did not fulfill the requirements of the EN 14214 standard concerning the oxidation stability (~0.6 h) and some impurities. The third MEs (SoSuME-EN) were fully compliant with the standard. Five formulations were phenolic-based, containing single or mixed antioxidant compounds of different molecular structures; one was amine-based. Different dosages of the formulations were added to the ME samples (corresponding to the addition range ~50-48300 ppm). The MEs stability expressed as induction periods, IPs, determined by the Rancimat method, were used for calculation of stabilization factors, SFs, indicating the efficiency of the applied formulation. The formulation containing TBHQ was the most efficient concerning the lowest consumption rate and the highest SF achieved for the low quality ME. 2,2?-methylene-bis-(4-methyl-6-tert-butylphenol) was linked with higher antioxidant potency than amine-based formulation and the phenolic com-pounds with two bulky tert-butyl groups. Among 4 selected phenolic additives, BHT and 2,2?-methylene-bis-(4-methyl-6-tert-butylphenol) proved similar efficiency in SoSuME-EN (at ~500 ppm they produced SF~2), while it took twice of this amount for mixed butylphenols to achieve the same effect.

Effect of leaf and fruit extracts of Schinus molle on oxidative stability of some vegetables oils under accelerated oxidation

The most highly recommended oils for the diet are those which are rich in unsaturated fatty acids. However, the presence of these components in the oils is related to oxidation, which can be determined by the induction period. Further safety and the prolongation of the storage period for such oils can be achieved by the addition of efficient antioxidants, which today are preferably from natural sources. In order to contribute to the related research, the main objective of this study was to evaluate the efficacy of Schinus molle extracts compared to synthetic antioxidants (BHT) in delaying the oxidation of some vegetable oils. The results of the present study showed that the fruit and leaf extracts of Schinus molle presented activities and potential for being used as antioxidants in vegetable oils based on the tested methods (DPPH and ABTS). The extracts were also characterized as containing phenolic compounds by the Folin Ciocalteau method and by high performance liquid chromatography (HPLC). The action of the extracts as natural antioxidants was proven in the vegetal oils of chia (Salvia hispanica) and peanut (Arachis hypogaea) by the Rancimat method. It was observed that the oils increased their resistance to oxidation when incorporated with the extracts of Schinus molle, and the extract from the leaves increased the induction period of peanut oil by more than three hours (from 19.5 to 22.9 hours) with an extract concentration of 2.5%. The fruit extract was more efficient in delaying the oxidation of chia oil, prolonging its induction period by more than one hour with a concentration of 2.5% (from 3.1 to 4.3 hours). According to the results, the extracts of Schinus molle have favorable properties for possible use as an additive which inhibits the oxidation process of the tested vegetables oils.

Safety Factors of Oils Marketed in Iran and Applicable Strategies in Control of Food Derived Cardiovascular Diseases

Background: The proposed criteria for a healthy daily diet play a drastic role in the prevention of non-communicable disease. Several cases of acute and chronic diseases occurred due to the presence of toxic and unsafe agents in the body. Trans and some saturated fatty acids as an example of these unfavorable components, could pose some dangerous effects on human health such as cardiovascular disease. Objective: In the current study, health criteria were undertaken to evaluate the safety of collected edible oils samples from Iranian market, and then some of the approaches for elimination and control of arisen health concerns were discussed. Methods: Totally 18 edible oil samples including cooking oil (n=5), frying oil (n=9) and table margarine (n=4) were collected from Tehran local market and were analyzed in 2016. The fatty acid profile was determined by using gas chromatography equipped with a flame ionization detector. Furthermore, the stability of frying oil was also measured by the Rancimat method. Results: All samples contained the trans and saturated fats in concentrations lower than the maximum recommended values (1%, 2% and 4% of trans for cooking oils, frying oils and table margarines, and 30% and 48% of saturation in frying oils and table margarines, respectively). The frying oils demonstrated the desired stability against high temperatures. Optimization of stability was done mainly by the addition of palm oil to the formula in the past. However, based on the fact of the high saturation of palm oil and its carcinogenicity under uncontrolled consumption, a risk assessment conducted in Iran led to the limited import of palm oil. This approach resulted in the production of healthier alternatives in the country. Conclusion: The usage of applicable approaches such as inter-esterification, fractionation and blending by more stable oils fractions is suggested to achieve healthier products.

Reproducibility of PetroOxy and its correlation with the Rancimat method

The current trend of reducing greenhouse gas emissions and carbon footprint as well as legislation requirements means an increase in the effort to replace fossil fuels by using renewable sources. One of the possibilities is usage of methyl esters (FAME or UCOME) as a bio-component in diesel fuel. Now the maximum FAME content in diesel is 7 vol% (according to the standard EN590 – B7). Increasing the proportion of FAME means a deterioration in oxidation stability. FAME is produced by the transesterification of the triglycerides present in vegetable oils. A major disadvantage of biodiesel (FAME) is ability to be slowly oxidised by air oxygen. Oxidation products may impair fuel properties, quality and engine performance. This is the reason why the oxidation stability of diesel and biodiesel is an important quality parameter. It could be detected using several methods, for example: Rancimat, PetroOxy or thermal techniques. The Rancimat method is intended for biodiesel and for diesel with a minimum 2 vol% content of FAME as mentioned in the standards EN 590 and EN 14214. The disadvantage is the time required for this method (more than 8 h for biodiesel and 20 h for diesel). The PetroOxy is shorter and its results can be converted to Rancimat stability. The set of 75 samples (40 samples of B7 and 35 samples of FAME) was measured using both mentioned methods. Three values of oxidation stability were determined for all of the analysed samples. In the first laboratory, oxidation stability of the samples was measured using both methods. In the second laboratory, oxidation stability was measured using only the PetroOxy. The PetroOxy results from both laboratories were compared with a high correlation value (R2 = 0,954). In the next step, outliers were removed from dataset. Experimental results of the Rancimat method were correlated with recalculated values of PetroOxy method from both laboratories. Correlation equation provided by the manufacturer of PetroOxy was used for recalculation of PetroOxy results to Rancimat results at first. Measured results were then compared with recalculated results. The largest difference in results was found in the B7 samples. Because of these differences the correlation equation between PetroOxy and Rancimat was optimized. Two different equation were made (for each laboratory). The recalculated oxidation stability results were compared with the primary results from Rancimat. The newly correlated values showed a higher degree of agreement with the experimental data than when the results were recalculated using the correlation equation provided by manufacturer. These optimized correlation equation have proven to be more suitable for industrial laboratories.

Kinetics of Lipid Oxidation in Ternary Mixtures of Grape, Sesame and Sunflower Oils by Rancimat Method

O óleo extraído das sementes de uva é um produto com excelentes características antioxidantes e nutricionais, que pode ser utilizado na indústria de alimentos. Devido a essas características, este óleo foi incorporado, juntamente com o óleo de gergelim, em diferentes proporções, ao óleo de girassol, mantido na proporção de 50% em todas as misturas. Os óleos puros e misturas foram avaliados quanto à estabilidade termo-oxidativa (índice de estabilidade do óleo, OSI), compostos fenólicos, DPPH, cromatografia em fase gasosa, cinética de oxidação, entalpia e entropia e prazo de validade (a 25 ° C). A equação de Arrhenius e a teoria do complexo ativado foram utilizadas para estimar as energias de ativação, entalpias e entropia de ativação, variando de 80,66 a 90,37 kJ / mol, 77,84 a 86,61 kJ / mol e -129,46 a -104,37 J / mol K, respectivamente. O óleo de uva puro e as misturas com a maior proporção destes adicionados (B1 e B2) apresentaram os melhores valores em todos os parâmetros analisados. Os valores de energia livre de ativação (ΔG), que variaram de 27,68 a 38,59 kJ / mol, unificaram e verificaram os resultados dos outros parâmetros cinéticos, que indicam uma menor taxa de oxidação lipídica para a mistura B1, com maior proporção de uvas adicionadas.