• Journal of the Korean Society of Food Science and Nutrition
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• v.45 no.10
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• pp.1513-1517
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• 2016

Rice bran contains high amounts of fiber and various phytochemicals, including vitamin E, ${\gamma}$-oryzanol, and phenolic acids. The oxidative stabilities of corn oil added with three rice bran extracts from two rice cultivars (Dasan 1 and Ilpum) were evaluated. The three rice bran extracts were unsaponifiable matter of rice bran (USM), methanolic extract of rice bran oil (MEO), and methanolic extract of defatted rice bran (MEDR). Each sample was stored at $50^{\circ}C$ for 24 days. Oxidation of these samples was determined every 3 days by measuring the peroxide value (POV) and conjugated diene value (CDV). Vitamin E content was analyzed on day 0 and day 24. The results show that the POV and CDV values of samples increased gradually during the storage period. The order of oxidative stability was shown as BHT> MEDR> MEO> USM> control, regardless of cultivars. In the case of vitamin E, ${\alpha}$-T, ${\gamma}$-T, ${\alpha}$-T3, and ${\gamma}$-T3 contents decreased by 89%, 31%, 83%, and 32% after storage for 24 days, respectively. In conclusion, MEDR showed higher oxidative stability and may have potential as a source of natural antioxidants in the oil industry.

• Korean Journal of Food Science and Technology
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• v.40 no.2
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• pp.141-145
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• 2008

Oxidative stabilities of sesame oil prepared from black sesame flour and white sesame flour, and commercial sesame oil prepared from whole white sesame were compared by measuring oxidation induction periods, peroxide values and electron donating abilities of each oil. Oxidation induction period (12.25 hr) of sesame oil prepared from black sesame flour was longer than those (4.37 and 9.1 hr, respectively) of sesame oil from white sesame flour and commercial sesame oil. Peroxide values of sesame oil prepared from black sesame flour, sesame oil prepared from white sesame flour and commercial sesame oil were 1.3, 18.2 and 1.7 meq/kg oil, respectively. We ascertained that the oxidative stability of sesame oil prepared from black sesame flour was superior than sesame oil from white sesame flour as well as ommercial sesame oil. This was based on the fact that electron donating ability of sesame oil prepared from black sesame flour was 9% higher than that of sesame oil prepared from white sesame flour at the same concentration. The superior oxidative stability of sesame oil prepared from black sesame flour was expected, not only because only it had lignans such as sesamol and sesamolin, but also because of its brownish coloring compounds such as tannin which were not contained in white sesame flour.

• Transactions of the Korean hydrogen and new energy society
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• v.30 no.2
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• pp.128-135
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• 2019

In this study, the mesoporous $SiO_2$ (5, 10, or 15 wt%) was incorporated into the polybenzimidazole matrix in order to improve the proton conduction as well as physiochemical properties of composite membrane. The chemical structure of mesoporous $SiO_2$ and crystallinity of as-prepared membranes were analyzed by Fourier-transform infrared (FT-IR) spectroscopy and X-ray diffraction (XRD) analysis, respectively. The thermal stability of the pristine $X_1Y_9$ and composite membranes were evaluated by thermogravimetric analyzer (TGA). On other side, the physical and chemical properties of the pristine $X_1Y_9$ and composite membranes were also determined by acid uptake and oxidative stability tests, respectively. With the incorporation of 15 wt% $SiO_2$, the composite membrane exhibits the higher proton conductivity that may be applicable for non-humidified high temperature fuel cell applications.

• Applied Biological Chemistry
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• v.37 no.3
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• pp.168-174
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• 1994

Effects of filtration and centrifugation on the oxidative stabilities of sesame oils during storage at $70^{\circ}C$ were studied by combination of determining peroxide values and conjugated dienoic acid values of oils and measuring the hexanal formation using headspace gas chromatography. Crude sesame oil from roasted seeds contained more free fatty acids, conjugated dienes, and metals (Fe, Cu, Mg and Zn); on the other hand, higher contents of moisture and ${\gamma}-tocopherol$ were found in the filtered or centrifuged oil. Only filtered oil contained more peroxides than the crude oil in spite of the color advantage of the highest L and b values among three oils. All the oils showed the tendency of increasing in total color difference during storage at $70^{\circ}C$, fatty acid compositions were relatively constant except for decreasing tendency of linoleic acid in filtered oil. No significant difference at 1% in the oxidative stabilities was observed between centrifuged oil and crude oil with higher susceptibility to the oxidation in the filtered oil. Centrifuged sesame oil was the best in the aspect of both oxidative stability and the oil color.

• Food Science of Animal Resources
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• v.39 no.3
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• pp.446-458
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• 2019

The aim of this study was to investigate the oxidative status and quality characteristics of four animal skin-derived fats extracted using an identical extraction method. Pressurized hot water extraction, a green extraction method, was used to extract animal skin fats (duck, chicken, swine, and bovine skin). Multiple experiments were performed during accelerated storage at $60^{\circ}C$ for 90 days. Quality characteristics, such as extraction yield, iodine value (IV), fatty acid composition, and fat viscosity were determined. In addition, indicators for oxidative status, including acid value (AV), peroxide value (PV), p-anisidine value (p-AV), thiobarbituric acid reactive substances (TBARS), conjugated dienes (CD), and total oxidation (totox) values were evaluated. The fat extraction yield was highest in bovine fat, followed by duck, swine, and chicken fats. The IV was higher in duck and chicken fats. Duck fats contained the most unsaturated fats and the least saturated fats. Fat oxidation indicators, such as PV, TBARS, and totox values, were relatively higher in duck fats during storage compared to the other fats. Other indicators, including AV, p-AV, and CD, were similar in duck, chicken, and swine fats. Viscosity was similar in all the tested fats but markedly increased after 70 days of storage in duck fats. Our data indicate that duck skin fat was more vulnerable to oxidative changes in accelerated storage conditions and this may be due to its higher unsaturated fatty acid content. Supplementation with antioxidants might be a reasonable way to solve the oxidation issue in duck skin fats.

• Journal of Animal Science and Technology
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• v.63 no.1
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• pp.46-57
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• 2021

Fruits with antioxidant enrichment can be an economically affordable supplement for mitigating oxidative damage prone spermatozoa membrane pathologies. Computer-assisted sperm analyzer and oxidative status were utilized to evaluate the impact of watermelon (Citrullus lanatus) fortification of dextrose saline as diluent for rooster semen and fertility response of hens inseminated. Watermelon juice and dextrose saline were used to formulate diluent of 7 treatments consisting of unextended semen (positive control), 10%, 20%, 30%, 40%, 50% and only dextrose saline (negative control) designated as Treatments 1-7. Pooled semen was obtained from fertile roosters and equilibrated with diluents at ratio 1:2 in the various treatments and were evaluated using computer software coupled microscope and seminal oxidative status assay. 168 laying hens randomly divided into 7 treatment of 8 replicates and 3 hen per replicate. Hen were everted, and semen (2 × 108 Spermatozoa) deposited intra-vagina and eggs collected over 8 weeks to assess fertility and hatchability of eggs laid. The result obtained revealed that watermelon-dextrose saline rooster semen diluent enhanced progressive motility, sperm kinetics and lowered non-progressive motility in T2-T6 compared to T7 over the 3 hours of evaluation. Watermelon addition to rooster semen diluent enhance the antioxidant capacity of rooster semen and lowered lipid peroxide generation. The percentage fertility was highest in T3 (81.01%) and T4 (81.24%) with lowest value obtained in T7 (73.46%). The hatchability of eggs set of hens inseminated with undiluted semen (71.46%) was lower than values for hens inseminated with watermelon inclusive extended semen (75.71%-80.39%). The optimal inclusion of 30%-40% watermelon in dextrose saline diluent enhance rooster semen kinetics, seminal oxidative stability and egg fertility.

• Journal of Life Science
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• v.33 no.7
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• pp.586-592
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• 2023

Oxidative stress is a critical factor affecting the quality and viability of sperm during boar semen storage. Oxidative stress is also a significant concern during the process of freezing semen. The process of semen storage involves exposing the sperm to various stressors, including temperature changes, cryoprotectants, and extended periods of incubation. In addition, oxidative stress can lead to the production of reactive oxygen species (ROS) within the sperm, resulting in oxidative damage to cellular components, such as lipids, proteins, and DNA. Striking a balance between ROS production and the antioxidant defense system is crucial for maintaining sperm viability and functionality during semen storage. Moreover, the prolonged storage of boar semen leads to an increase in ROS levels, which can impair sperm motility, membrane integrity, and DNA integrity. ROS-induced lipid peroxidation affects the fluidity and stability of sperm membranes, leading to decreased sperm motility. Moreover, oxidative damage to the DNA can result in DNA fragmentation, compromising the genetic integrity of the sperm. In conclusion, oxidative stress is a significant challenge in maintaining sperm quality during boar semen storage. Understanding the mechanisms underlying oxidative stress and their impacts on sperm function is crucial for developing effective strategies to minimize oxidative damage and improve sperm storage outcomes.

• Carbon letters
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• v.25
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• pp.60-67
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• 2018

In the present work, capability of thymolphthalein-grafted graphene oxide, which was successfully synthesized in this study, in stabilization of polypropylene against thermal oxidation were investigated and compared with that of SONGNOX 1010, a commercially used phenolic antioxidant for the polymer. The modified graphene oxide were incorporated into polypropylene via melt mixing. State of distribution of the nanoplatelets in the polymer matrix was examined using scanning electron microscopy and was shown to be homogeneous. Measurements of oxidation onset temperature and oxidative induction time revealed that thymolphthalein-grafted graphene oxide modifies thermo-oxidative stability of the polymer in the melt state remarkably. However, the efficiency of the nanoplatelets in stabilization of polypropylene against thermal oxidation in melt state was shown to be inferior to that of SONGNOX 1010. Furthermore, oven ageing experiments followed by Fourier transform infrared spectroscopy showed that the modified graphene oxide improves thermo-oxidative stability of the polymer strongly in the solid state, so that its stabilization efficiency is comparable to that of SONGNOX 1010.

• Journal of the Korean Society of Food Science and Nutrition
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• v.34 no.1
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• pp.93-98
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• 2005

Total tocopherol and phenol contents were determined for virgin and pure oilve oil, and their autoxidation and thermal oxidation were compared with those of commercial soybean oil, in the presence or absence of fluorescent light. The total tocopherol contents of virgin, pure olive oil, and soybean oil were 15.7, 11.2, and 80.7 mg/100 g, respectively. Their total phenol contents were 10.4, 1.6 and 0.5 mg/l00 g, respectively. In autoxidation under dark place at 45$^{\circ}C$, the oxidative stability of the substrate oils decreased in order of virgin oilve oil, pure olive oil, and soybean oil. The average temperature coefficients of the virgin, pure olive oil and soybean oil in the range of 45∼$65^{\circ}C$ were 1.73, 1.83 and 1.64, and the activation energies were 26.86, 29.49, and 24.07 KJ/mol, respectively. In temperature range of 45∼$65^{\circ}C$, pure olive oil was the most susceptible to temperature change, whereas soybean oil the least. In autoxidation under fluorescent light at 45$^{\circ}C$, the oxidative stability of substrate oils decreased in the order of soybean oil, pure olive oil, and virgin olive oil. In thermal oxidation at 18$0^{\circ}C$, the oxidative stability of substrate oils decreased in order of pure olive oil, virgin olive oil, and soybean oil.

• Journal of the Korean Society of Food Science and Nutrition
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• v.39 no.11
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• pp.1715-1718
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• 2010

The oxidative stability of grape seed oils (GSOs) prepared from grape seeds roasted at different temperatures (100, 150 and $200^{\circ}C$ for 1 hr) was evaluated and compared with that of GSO from unroasted grape seed. Stability of the GSOs stored in air at $50^{\circ}C$ up to 40 days was assessed by acid value (AV) and peroxide value (PV). Simultaneously, the cont ents of tocopherols and tocotrienols and color changes were monitored up to 40 days. During the storage period, the PV of the unroasted GSO increased from 1.95 to 90.72 meq/kg. On the other hand, the PV for GSOs roasted at 100, 150 and $200^{\circ}C$ increased from 1.96, 2.03, 1.98 to 76.09, 71.72, 49.38 meq/kg, respectively. AV is in conformity with PV. Color development of GSOs increased as roasting temperature increased. The contents of tocopherols and tocotrienols in GSOs increased as roasting temperature increased from 100 to $200^{\circ}C$. The contents of tocopherols and tocotrienols gradually decreased along with the storage period. These results suggest that roasting treatment prolongs the oxidative stability of GSOs.