• Journal of Food Hygiene and Safety
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• v.22 no.4
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• pp.311-316
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• 2007

Trans fatty acid components separated and quantified using a SP-2560 capillary column in a gas chromatograph (GC) with flame ionization detector (FID). Trans fatty acid and total fatty acid contents were measured in 21 corn oils. Ranges of values for trans fatty acid (tFAs) contents of total fat (as g/100g fatty acids) were com oils $0.65{\pm}0.31$. Corn oils were heated at $175{\pm}5^{\circ}C$ for 5mins $(0{\sim}15\;times)$. The contents of tFAs (g/100) were increased from 0.292 (0 time) to 2.585 (15 times) in com oil. When frying oils (15 times) were incubated at $20{\pm}5^{\circ}C$ for 150 days, the contents of tFAs (g/100g) were increased from 2.585 to 3.683 in com oil. The amounts of tFAs (g) per serving size of frying oils (15 times) were increased from 0.01 to 0.18 in corn oil. The levels of the 18:1 trans isomers increased significantly the time of reusing of com oil.

• Korean Journal of Food Science and Technology
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• v.30 no.2
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• pp.288-292
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• 1998

Thermooxidative stabilities of soybean oil, beef tallow and palm oil were studied during frying of steamed noodles. Steamed noodles were fried in $150^{\circ}C$ oils for 70 sec at the interval of 30 min. The frying oil was taken every 8 hrs for the analysis of peroxide value (PV) and free fatty acid (FFA) content, fatty acid composition, and tocopherol and tocotrienol content. A little change was shown in PV and FFA content in soybean oil during frying; on the other hand, rapid increase in beef tallow and palm oil was observed. Unsaturated fatty acid content was the highest in soybean oil, followed by palm oil and beef tallow. While fatty acid composition in soybean oil was not changed during frying, unsaturated fatty acid content decreased and saturated fatty acid increased in beef tallow and palm oil, which showed susceptibility to the oxidation. The ratio of linoleic acid to palmitic acid did not show difference with frying time in soybean oil: however, it decreased in other oils with a high correlation with frying time and higher decreasing rate in palm oil was observed. These suggested that soybean oil was the most stable to thermooxidation and the stability was followed by beef tallow and palm oil. Tocopherol was disappeared during frying and 87.5, 81.1, and 73.1% were remained in soybean oil after 8, 16 and 24 hour frying, respectively. Also the rate decreased in the order of ${\gamma}-,\;{\beta}-\;and\;{\alpha}-tocopherol$. However, 34.2 and 169.0 ppm tocopherol and tocotrienol which were present in control samples of beef tallow and palm oil were completely disappeared by 8 hr frying. Therefore, high thermooxidative stability of soybean oil resulted from higher residual amount of tocopherol during frying, and lower stability of palm oil than beef tallow was partly due to high degree of unsaturation.

• Korean Journal of Food Science and Technology
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• v.19 no.6
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• pp.556-560
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• 1987

In this study, silicone oil was added into soybean oil in order to investigate its effect on acid value (AV), carbonyl value (COV), TBA value, fatty acid composition and color intensity of soybean oil during frying at $170^{\circ}C$. It was found that the AV, COV and TBA value were significantly decreased as the concentration of silicone oil increased from 0 to 5 ppm in soybean oil after frying for 7 hours. The color intensity was also decreased by 26% of color of 7 hours-heated soybean oil without silicone oil addition. Little changes in fatty arid composition was measured between the samples after 7 hours frying. From the overall result of this study, addition of silicone oil by 1 ppm was recommended for effective reduction of rancidity development of soybean oil ing frying.

• Journal of the Korean Applied Science and Technology
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• v.4 no.2
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• pp.15-18
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• 1987

The storage stability of Instant Ramyon by industrially prepared with palm, beef tallow and blended rapeseed oils for frying oil was studied. The products was stored under fluorescent light at $60^{\circ}C$ with illumination of 9,000 lux. Changes of peroxide value, total carbonyl value, and absorbance at 232 nm of lipids extracted from Ramyon were investigated during storage. The storage stability of Ramyon prepared with oils containing TBHQ had better than that prepared with a mixture of BHA and BHT. The Ramyon prepared with 4 part of rapeseed oil to 6 part of tallow containing 0.02% BHA/BHT showed higher storage stability than that prepared with palm oil alone but showed lower stability than that prepared with tallow alone both under the same condition of antioxidant treatment.

• Preventive Nutrition and Food Science
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• v.7 no.3
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• pp.255-260
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• 2002

Yukwa is a popular Korean traditional fried rice snack. The high fat content and porous structure of Yukwa cause it to rapidly become rancid, presenting difficult challenges for commercial distribution. In this study, an-tioxidant activities of green tea extracts (GTE) were evaluated in Yukwa fried in soybean oil (SBO), rice bran oil (RBO) and winterized rice bran oil (WRBO) during storage at 4$0^{\circ}C$ for 12 weeks. Lipid oxidation of Yukwa was determined by acid value (AV), peroxide value (POV), p-anisidine value(AnV), totox value and sensory evaluation. The addition of GTE to the oils reduced the increases in AV, POV, AnV, and totox. Totox increased most vapidly in Yukwa fried in SBO, fellowed by RBO>WRBO>SBO+200 ppm GTE>RBO+200 ppm GTE > WRBO + 200 ppm GTE (p<0.05). Sensory evaluation revealed that the addition of 200 ppm GTE delays rancidity in Yukwa by 7~8 weeks; providing compelling evidence that GTE is an effective antioxidant for Yukwa.

• Journal of the Korean Applied Science and Technology
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• v.4 no.2
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• pp.7-13
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• 1987

A preliminary investigation was performed to evaluate the possibility of partially replacing palm oil and beef tallow by rapeseed oil for frying oils of instant Ramyon manufacturing. The AOM stability of rapeseed oil was inferior than of palm oil, but was comparable to that of beef tallow. When rapeseed oil was blended with palm oil or beef tallow, the AOM stability of the blended oil was improved. As far as AOM stability is concerned, best results were obtained with a blending ratio of 3 part of rapeseed oil to 7 part of palm oil and a ratio of 4 part of rapeseed oil to 6 part of beef tallow. These blended rapesee oils was retarded the formation of conjugated dienes and polymers during heating. The antioxidative effects on the stabilities of AOM and thermal in blended rapeseed oils showed that TBHQ was superior to tocopherols and a mixture of BHA and BHT was inferior.

• Korean journal of food and cookery science
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• v.23 no.6
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• pp.1015-1024
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• 2007

Trans-fatty acids (TFAs) are defined as the sum of all unsaturated fatty acids that contain one or more non-conjugated double bonds in a trans configuration. Dietary trans- fatty acids originate from commercially hydrogenated oils and from dairy and meat fats. From the perspective of the food industry, partially hydrogenated vegetable oils are attractive because of their long shelf life, stability during deep-frying, and semisolidity, which can be customized to enhance the palatability of baked goods and fried foods. Although no definite differences have been documented so far between the metabolic and health effects of industrial and ruminant TFAs, the intake of industrially produced TFA has declined, and in Europe, the majority of TFAs are of ruminant origin. Due to the scientific evidence associating TFA intake with increased risk of coronary heart disease (CDH), the Korea Food and Drug Administration (KFDA) issued a final rule that requires the amount of trans fat present in foods to be declared on the nutrition label, by December 1, 2007. In addition, many food manufacturers who use partially hydrogenated oils in their products have developed, or are considering ways, to reduce or eliminate trans-fatty acids from certain food products.

• Korean Journal of Food Science and Technology
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• v.10 no.2
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• pp.112-118
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• 1978

Four domestic frying oils (soybean, corn, rapeseed and rice bran oil) were studied on their changing properties according to thermal oxidation by means of chemical analysis of their compositions and measurements of various physical and chemical properties. The content of linoleic acid which is an essential unsaturated fatty acid and the total amount of unsaturated fatty acids were highest in soybean oil (53.2% and 80.3% respectively) among the unheated frying oils and the degree of its thermal degradation was lowest during the continuous heating period for 48 hours at $180^{\circ}C$. However in general, the contents of unsaturated fatty acids were sharply decreased by thermal oxidation whereas the saturated fatty acid contents ranging 10-17% were not changed considerably, which largely agreed with the results of iodine value measurements. The free acid and peroxide values were also lowest in soybean oil (0.09 and 5.6 respectively) among the unheated oils whereas an anomalously high free acid value was observed in rapeseed oil (54.8) which was packed in unleveled glass bottles. Such a high value is probably ascribed to the photo-catalyzed oxidation during storage. The viscosity measurements have shown similar values before heating, but after thermal oxidation for 32 hours the rapeseed and rice bran oils became too thick to measure viscosity by capillary flow method with heavy darkening in color.

• Journal of the Korean Society of Food Science and Nutrition
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• v.29 no.1
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• pp.120-127
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• 2000

Deep-fat frying is a common cooking practice. There has been considerable concern regarding the mutagenic and carcinogenic potential of thermally oxidized oils. Studies on deep-fried foods so far have revealed not much on the mutagenicity of the oils in the foods. Therefore, in the present study, it was attempted to investigate the mutagenicity ofthe thermally oxidized safflower oil. Oil was heated in a home-fryer at a temperature of 180$\pm$3$^{\circ}C$ for 48 hours. Oil samples were taken at 0, 8, 16, 24, 32, 40 and 48 hours of heating, respectively. Each sample was used to study the changes in peroxide value (POV), acid value (AV), iodine value (IV), conjugated dienoic acid (CDA) content, %, and fatty acid composition. Another series of samples were fractionated into non-polar and polar fractions by column chromatography. The mutagenicity of the samples taken from the thermally oxidized oils, as well as the non-polar and polar fractions of the thermally oxidized oils, was investigated with the Ames test. The Ames test was carried out with and without metabolic activation. Bacterial tester strains used in the present study were the histidine auxotrophic strains of Salmonella typhimurium TA100, TA1535 and TA102 were used for the detection of base pair mutations, and TA98 and TA1537 for frame shift mutations. Each series of samples was dissolved in tetraphydrofuran (inhibitor-free) and tested at doses ranging from 0.05 to 5 mg/plate. None of the oil samples taken during the 48 hour oxidation period showed any mugagenic activity. This was the case, even after the activaton with 59 mix. Also, none of the polar and non-polar fractions showed any mutagenic activity on all the strains tested.

• Korean Journal of Food Science and Technology
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• v.15 no.1
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• pp.77-89
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• 1983

Properties and frying performance of domestic rice bran oil were studied. For this purpose, the analyses on the following characteristics were performed and their comparison with the characteristics of soybean oil was made: fatty acid composition, glycerides, composition, acid value, specific gravity, color, petroleum ether insoluble oxidized fatty acid, viscosity, smoke point, foam test, and water solubility. The results were as follow: 1) Fatty acid composition of domestic rice bran oil by gas chromatography was same as perviously reported, and similar to the fatty acid composition of the rice bran oil in foreign countries. Also the glyceride composition of domestic rice bran oil was analyzed by the methods of TLC, column chromatography, and high performance liquid chromatography. The results were monoglyceride ranged from one to four percent; diglyceride 30-30% and triglyceride 66-80%. Consequently, the composition was proven completely different from that of the other edible oils. 2) The high contents of mono-glyceride in rice bran oil resulted in high values of specific gravity and water-solubility respectively. However, high contents mono glyceride and diglyceride indicated little affection to changes of acid value, color, petroleum ether insoluble oxidized fatty acid, and smoke point on frying. 3) Because of low contents of linoleic acid, domestic rice bran oil was estimated stable on frying, whereas soybean oil was easily polymerized. 4) A serious foaming and low smoke point on Frying in domestic rice bran oil were caused by its impurities. It seems that monoglyceride and diglyceride had little relation with foaming and smoke point. 5) Oils with serious foaming and low smoke point on frying caused a substantial quality loss in terms of flavor and appearance of fried materials.