Pistacia atlantica subsp. mutica (PAM) and kurdica (PAK) kernel oils showed significantly lower unsaturated to saturated fatty acid ratios (6.39, 6.33, respectively) and calculated oxidizability (Cox) values (3.99, 4.13, respectively) than those of the P. vera L. cv. Ohadi (PVO) kernel oil (8.91, 4.41) samples. The highest peroxide value was observed for the PAK oil (4.07 mequiv kg−1) (PAM, 1.94; PVO, 0.37) samples. Iodine values for the PAM, PAK, and PVO oils were 104.26, 104.77, and 110.66, respectively. The saponification number of the PVO oil was significantly greater than the PAM and PAK oils, which were statistically not different. The unsaponifiable contents, which were composed mainly of sterols, ranged from 5.63 to 6.14%. Statistically the total tocopherols contents of the PAM (818.58 mg α-tocopherol kg−1) and PVO (815.90 mg α-tocopherol kg−1) oils were significantly higher than that of the PAK oil (499.91 mg α-tocopherol kg−1). Total phenolics contents differed significantly, the greatest concentration was for the PAM oil (81.12 mg gallic acid kg−1), followed by the PVO (62.84 mg gallic acid kg−1) and PAK (56.51 mg gallic acid kg−1) oil samples. The wax contents of the oil samples were statistically in the same range, namely 5.67–6.48%. Oxidative stability data indicated that the PAM oil is the most resistant to the formation of lipid oxidation products, followed by the PAK and PVO oil samples.

Chemical Composition and Oxidative Stability of Kernel Oils from Two Current Subspecies of Pistacia atlantica in Iran

Kinetics of lipid oxidation in omega fatty acids rich blends of sunflower and sesame oils using Rancimat.

A comparative study was carried out in order to evaluate the kinetics of the formation of a number of primary and secondary oxidation products during oxidation of olive oil in the Rancimat test at 100–130 °C. There were good correlations between the Rancimat index (OSI) and stability indices (IP) measured in the Rancimat test with no significant differences in kinetic parameters calculated from them. Mean values of the temperature coefficient, Q
 10 number, activation energy (E
 a), frequency factor (A), and free energy of activation (ΔG
 ++) for olive oil oxidation were calculated to be −3.44 × 10−2 °C−1, 2.21, 98.91 kJ/mol, 12.17 × 1012 h−1, and 128.25 kJ/mol, respectively. Each unit change in E
 a was accompanied by an average 1.43 × 1012 change in A, indicating a higher contribution for factor A than for E
 a to the olive oil stability. The E
 a and A correlated well with the values of enthalpy and entropy, respectively. The values of OSI or IP could be described well by the ΔG
 ++ values. Kinetic data indicated that olive oil stability is more affected by the indigenous antioxidants than by the fatty acid composition.

Evolution of Oxidative Values during Kinetic Studies on Olive Oil Oxidation in the Rancimat Test

Simultaneous monitoring of the conventional qualitative indicators during frying of sunflower oil

Abstract Cutting fluid is crucial in ensuring surface quality and machining accuracy during machining. However, traditional mineral oil-based cutting fluids no longer meet modern machining’s health and environmental protection requirements. As a renewable, pollution-free alternative with excellent processing characteristics, vegetable oil has become an inevitable replacement. However, vegetable oil lacks oxidation stability, extreme pressure, and antiwear properties, which are essential for machining requirements. The physicochemical characteristics of vegetable oils and the improved methods’ application mechanism are not fully understood. This study aims to investigate the effects of viscosity, surface tension, and molecular structure of vegetable oil on cooling and lubricating properties. The mechanisms of autoxidation and high-temperature oxidation based on the molecular structure of vegetable oil are also discussed. The study further investigates the application mechanism and performance of chemical modification and antioxidant additives. The study shows that the propionic ester of methyl hydroxy-oleate obtained by epoxidation has an initial oxidation temperature of 175 ℃. The application mechanism and extreme pressure performance of conventional extreme pressure additives and nanoparticle additives were also investigated to solve the problem of insufficient oxidation resistance and extreme pressure performance of nanobiological lubricants. Finally, the study discusses the future prospects of vegetable oil for chemical modification and nanoparticle addition. The study provides theoretical guidance and technical support for the industrial application and scientific research of vegetable oil in the field of lubrication and cooling. It is expected to promote sustainable development in the manufacturing industry. 

/pdf/vegetable-oil-based-nanolubricants-in-machining-from-bsybb0js.pdf

Vegetable Oil-Based Nanolubricants in Machining: From Physicochemical Properties to Application

In this research, five different vegetable oils were oxidized at four different temperatures (373, 383, 393, and 403 K) under Rancimat test conditions. An increasing rate of oxidation could be observed as temperature increased. The natural logarithms of the kinetic rate constant (k value) varied linearly with respect to temperature, with the temperature coefficients (TCoeff) ranging from 6.95×10–2 to 7.40× 10–2 K–1 for the vegetable oils. On the basis of the Arrhenius equation and the activated complex theory, frequency factors (A), activation energies (Ea), Q10 numbers, activation enthalpies (ΔH++), and activation entropies (ΔS++) for oxidative stability of the vegetable oils were calculated. The A, Ea, Q10, ΔH++, and ΔS++ values for the vegetable oils ranged from 6.38×103 to 28.03×103 h–1, from 86.86 to 92.42 kJ/mol, from 2.08 to 2.18, from 83.64 to 89.20 kJ/mol, and from –116.66 to –104.35 J/mol K, respectively.

Kinetic parameter determination of vegetable oil oxidation under Rancimat test conditions

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Kinetic parameter determination of vegetable oil oxidation under Rancimat test conditions