• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
• /
• 1998.10a
• /
• pp.175-180
• /
• 1998

This paper describes evaluation of oxidation stability for diesel engine oils by Hot-tube oxidation tester at high temperature. Evaluation was rated by visual inspection of lacquer in capillary glass tube and TAN determination of used oil. Air, NO$_2$-air and SO$_2$-air mixed gases were used as oxidizing gas. One oil which has low oxidation stability is selected and reformulated by addition of some additives such as antioxidant, detergent and disperant to improve oxidation stability. As a results of reformulation, antioxidant and detergent was effective for improvement of high temperture oxidation stability on diesel engine oil.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.21 no.4
• /
• pp.135-143
• /
• 2013

In this study, we suggested effective countermeasure of biodiesel oxidation problems by investigating the oxidation degradation of biodiesels derived from variable resources and the level of oxidation stability of current distributing biodiesel blended fuels (2%) in Korea, and oxidation stability change according to storage time (for 3 month) and biodiesel blending ratio (2, 5, 7, 10%). By the composition analysis results of biodiesel from various resources which are possible to distribute in Korea, the biodiesel from animal fat has poor oxidation stability and cold performance, while the biodiesel from coconut and palm kernel which are considered as future potential raw material showed good oxidation stability and cold performance. The oxidation stability level of current distributing biodiesel blended fuels in Korea was excellent with showing over 30 hours (average 68 hours) stability, but the oxidation stability of the blended fuel with animal fat biodiesel having poor oxidation property (1.22 hours) was rapidly decreased to below 32 hours by mixing only 2%. Therefore, we have to pay attention to quality control of oxidation property, because the oxidation stability problem can be caused by increasing biodiesel blending ratio and diversifying raw materials those have worse property.

• Journal of the Korean Applied Science and Technology
• /
• v.7 no.1
• /
• pp.63-70
• /
• 1990

Influence of mixing ratio of blending oil (rice bran oil : RBD palm olein = 1 : 1, 1 : 4 mixture: w/w) and natural tocopherol, citric acid, and sodium polyphosphate on enhancement of oxidation stability of blending oil under the condition of tap water infulx(1 ml/min/200g oil) were compared by AOM test after heating these system at l80$^{\circ}C$. In addition, the effects of tocopherol, and synergist on oxidition stability were also tested with potato chips fried with blending oil(1 : 4 mixture). The result obtained were as followes; 1. The test of RBD palm olein addition of 50% and 80% against rice bran oil on oxidation stability showed that the higher the palm olein contents in blending oil, the higher the oxidation stability. 2. The test of oxidation stability, adding l00ppm, 200ppm and 400ppm of natural tocopherol in two different types of blending oils, A(1 : 1 mixture) and B(1 : 4 mixture), disclosed that blending oil B was more positively effective, and this trend was superior at 200ppm level particularly, Furthermore, oxidation stability was enhanced remarkably upon addition of 100ppm of natural tocopherol, and 50ppm of citric acid together with 50ppm, 100ppm and 200ppm of sodium polyphosphate in general. Especially, 200ppm of sodium polyphosphate addition induced the most synergetic effect on oxidation stability showing as much as 3 times compare to control. 3. The results of oxidation stability obtained by peroxide value on potato chips fried with blending oil (1:4 mixture} added tocopherol, citric acid and sodium polyphosphate and preserved at $60^{\circ}C$ revealed that addition of tocopherol and 50ppm of citric acid together with 200ppm of sodium polyphosphate treatment was the most synergistic coinciding with AOM test results.

• Preventive Nutrition and Food Science
• /
• v.17 no.2
• /
• pp.158-165
• /
• 2012

This study was designed to investigate whether the fatty acid composition could make a significant contribution to the oxidation stability of vegetable oils marketed in Korea. Ten kinds, 97 items of vegetable oils that were produced in either an industrialized or a traditional way were collected and analyzed for their fatty acid compositions and lipid oxidation products, in the absence or presence of oxidative stress. Peroxidability index (PI) calculations based on the fatty acid composition ranged from 7.10 to 111.87 with the lowest value found in olive oils and the highest in perilla oils. In the absence of induced oxidative stress, malondialdehyde (MDA), the secondary lipid oxidation product, was generated more in the oils with higher PI (r=0.890), while the tendency was not observed when the oils were subjected to an oxidation-accelerating system. In the presence of the oxidative stress, the perilla oils produced in an industrialized manner generated appreciably higher amounts of MDA than those produced in a traditional way, although both types of oils presented similar PIs. The results implicate that the fatty acid compositions could be a predictor for the oxidation stability of the vegetable oils at the early stage of oil oxidation, but not for those at a later stage of oxidation.

• Tribology and Lubricants
• /
• v.34 no.4
• /
• pp.160-167
• /
• 2018

Vegetable oils can contribute to the goal of energy independence and security owing to their naturally renewable resources. One of the representative vegetable oils is biodiesel, which is being used in domestic and European markets as a blended fuel with automotive diesel. Vegetable oils are promising candidates as base fluids to replace petroleum lubricants because of their excellent lubricity and biodegradability. We prepared biodiesel with a purity of 99.9% via the esterification of waste cooking oil. Blended biodiesel and Petro-lube base oil were mixed to produce five types of mixed lubricating oil. We analyzed the various characteristics of the blended biodiesel with Petro-lube base oil for different blending ratios. The lubricity of the vegetable lubricant improves as the content of biodiesel increases. In addition, since zinc dialkyldithiophosphates (ZnDTPs) are widely used as multifunctional additives in petroleum-based lubricants, we optimized the blending ratio for lubricity, oxidation stability, and shear stability by adding ZnDTP as a performance additive to improve the biodiesel properties, such as oxidation stability and hydrolysis. The optimized lubricants improve by approximately 25% in lubricity and by 20 times in oxidation stability and shear stability after the addition of ZnDTP.

• Journal of the Korean Chemical Society
• /
• v.19 no.1
• /
• pp.50-52
• /
• 1975

The oxidation stability of samples prepared by blending samples reported previously with diesel oil and diesel oil with additives(alkyl benzene and phenolic type of materials), was tested to study the mechanism of thermal oxidation stability of the regenerated lubricating oils. It was found that the improvement of thermal oxidation stability of such oils was caused by the formation of aromatic compounds, especially phenolic type of organic materials.

• Journal of the Korean Applied Science and Technology
• /
• v.6 no.1
• /
• pp.9-14
• /
• 1989

Effectiveness of some natural antioxidants were investigated by measuring the physico-chemical charcteristics and fatty acid composition during thermal oxidation in palm oil. Tocopherol showed most enhanced thermal oxidation stabilities compared to the other natural antioxidants. AR spice was no good AOM stability and changes of acid value but the other parameters were obtained desirable results. The changes of linoleic aicd content was slightly decreased during thermal oxidation. Addition of rosemary and glycyrriza extract increased the stabilities of oil less than tocopherol and AR spice. Order of antioxdative effects was tocopherol, AR spice and others. There was no significiant difference in stability of rosemary and glycyrriza extract.

• Tribology and Lubricants
• /
• v.11 no.5
• /
• pp.47-54
• /
• 1995

An advanced liquid lubricants for heat engines has been developed and tested successfully in a prototype engine. The lubricant possesses superior oxidation stability and high temperature stability and is capable of surviving for a minimum of three minutes at 425$^{\circ}$C (800$^{\circ}$C) at the ring zone and maintains stability at an oil sump temperature of 171$^{\circ}$C. The lubricant has been evaluated by the Cummins Engine Co. Out of a field of several dozens of lubricant, six lubricant was selected for a prototype 200 hours endurance testing. The NIST lubricant was one of the two lubricants that successfully finished the endurance testing. This paper describes the key lubricant considerations including oxidation and thermal stability, volatility, deposit control. The engine test conditions and the results will be presented.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.48 no.5
• /
• pp.589-595
• /
• 2015

Alginates are used to encapsulate various materials, including food, cosmetics, and pharmaceuticals. This study examined the properties and oxidation stability of fish oil capsules manufactured with calcium alginate gels. The fish oil capsules were manufactured by dropping sodium alginate solution and fish oil into a calcium chloride solution through nozzles. The membrane thickness, sphericity, rupture strength and deformation depth of the fish oil capsules were determined. The peroxide value of the fish oil was assayed to determine the oxidation stability of the capsules. The capsules measured approximately 3 mm with a membrane thickness of 90 μm independent of the amount of fish oil added. As the amount of fish oil encapsulated increased, the sphericity, rupture strength and deformation depth of the capsules decreased. The encapsulation efficiency increased until the amount of fish oil was 30%. The oxidation stability of fish oil in capsules was dependent on the type of nozzle, e.g., the oxidation stability of fish oil in capsules made using a double nozzle was greater than with a single nozzle. These results should lead to industrial application of fish oils including eicosapentaenoic (EPA) and docosahexaenoic (DHA) acids, as nutraceuticals.

• Food Science of Animal Resources
• /
• v.38 no.5
• /
• pp.1029-1042
• /
• 2018

This study aimed to investigate the use of golden thread extract (GTE), clove extract (CE), and commercially available nitrite for retarding lipid and protein oxidation and for maintaining color stability and sensory attributes in beef patties stored at $4^{\circ}C$. GTE, CE, and nitrite treatment samples were found to be efficient in retarding lipid oxidation as all three treatments resulted in low thiobarbituric acid reactive substance (TBARS) content (p<0.05). By using GTE, CE, and nitrite into beef patties, protein oxidation was not developed. Incorporation of GTE and CE into beef patties maintained color stability by protecting against the decrease of $L^*$, $a^*$, $b^*$, chroma, and hue angle values and exhibited significant influence on sensory characteristics, including color and odor of beef patties (p<0.05). Compared to commercially available nitrite, GTE and CE were more effective as antioxidants for inhibiting lipid oxidation, and preserving color stability of fresh beef patties. The study indicated that GTE and CE could be utilized efficiently to extend the shelf life of beef patties.