• Journal of the East Asian Society of Dietary Life
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• v.18 no.2
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• pp.181-189
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• 2008

In this study, changes in total trans fatty acid (tFA) and fat contents were determined in soybean oil, shortening, and olive oil after potato sticks were fried 30 consecutive times, respectively. Prior to frying, the potato sticks contained 3.8% fat, with 43.2% tFAs, After the first frying in soybean oil, the total tFA content of the potato sticks sharply decreased to 3.2%, and then it gradually increased to 8.1 % after 30 consecutive times of frying. However, the total fat content of the potato sticks, fried in soybean oil increased to 15.2% after the first frying and thereafter it decreased to 9.75% with 30 repeated episodes of frying. When the potato sticks were fried in olive oil, similar changes in tFA and fat contents were shown; while such changes were not observed when shortening was used. After 30 consecutive frying events, the tFA contents in the soybean oil and olive oil increased to 4.15 and 5.75%, respectively; however, such an increase was not observed in the shortening. One can assume that most of the tFAs in the fried oils were from the potato sticks, which contained relatively high tFA content during the repeated deep-frying process.

• Culinary science and hospitality research
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• v.24 no.2
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• pp.79-86
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• 2018

The purpose of current study was to evaluate the oxidative stability of soybean oil after frying according to storage temperature. The soybean oil after 10 times deep fat frying with potato sticks (10% w/w of oil) were stored during 10 days at 30, 60 and $90^{\circ}C$ and chemical properties were determined. The acid value and peroxide value were the highest and the iodine value were the lowest when the oil stored at $90^{\circ}C$. Expecially, the production rate of peroxide was fast at over $60^{\circ}C$. According to the results, frying oil should not be stored for more than 6 days at $30^{\circ}C$ after use. Since the oil used had already produced unstable peroxides, oxidation could proceed relatively quickly even at low temperatures. Therefore, it is desirable to keep the used oil at a temperature as low as possible.

• Journal of environmental and Sanitary engineering
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• v.4 no.1 s.6
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• pp.29-36
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• 1989

The purpose of this investigation was performed for chemical values related to rancidity of fat and oils extracted from deep-frying food in Seoul. The samples were collected according to kinds of fat and oils, sampling sites and food stuffs for frying. The results were as follows 1. The most used frying oils were rice bran oil $(37.0\%)$ and shortening $(29.6\%)$, followed by rapeseed oil $(14.8\%)$. 2. The chemical values related to rancidity of fat and oils extracted from deep-frying foods were the next on average. Acid value-1.42, peoxide value-39.82, dinitrophenyl hydrazine value-16.73 thiobarbituric acid value-0.263. However the highest value among oils was showed in rice bran oil and the lowest value was shortening. 3. For the classification of sampling sites, acid value and peroxide value of samples of the markets were found higher than them of environs of school and roadside, and the differences between them were significant (P> 0.01), while dinitrophenyl hydrazine value and thiobar bituric acid value were not showed the significant differences. 4. For the classification of foodstuffs for frying, there were not recognized significant differences among all kinds of them.

• Korean journal of food and cookery science
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• v.14 no.2
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• pp.177-181
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• 1998

The changes of the physico-chemical characteristics of potato and chicken frying oil with frying number were examined. The changes in temperatures of frying oil during the potato flying were greater than that during the chicken frying. The weight loss of potato during deep frying was about 21.9% and about 12.3% for chicken. The acid values and conjugated dienoic acid values of the potato and chicken frying oils increased with increased frying number. Their values were greater in the chicken frying oil than in the potato frying oil. The peroxide values of frying oil did not change regularly as frying number increased. But iodine values of the frying oils decreased with increased frying number. Linoleic acid content of the frying oil decreased, whereas oleic acid content increased with frying number.

• Journal of the Korean Dietetic Association
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• v.4 no.1
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• pp.99-108
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• 1998

The purpose of this study was to investigate the effect of frying methods of chickens ; deep-fat frying with raw chickens(A), with pre-cooked chickens(B) on the physicochemical properties of frying oil and fried chickens in the school foodservice. Acid, peroxide and TBA value of frying oil were significantly increased by increasing the number of frying times and those of method A were higher than those of method B. On the contrary, Iodine value was decreased significantly with increasing the number of frying times but there is no significant difference between method A and B. In fatty acids, the content of saturated fatty acid increased while that of unsaturated fatty acid decreased as the frying times increased. Also viscosity, yellowness and redness increased significantly by increasing the number of frying times. The content of vitamin $B_1 $, of fried chicken by the frying methods was not significantly different, but vitamin $B_2 $the method A was higher than by the method B. Ca, P, Na, K and Fe contents of fried chickens by the method A were higher than those by the method B.

• Food Science of Animal Resources
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• v.36 no.5
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• pp.612-616
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• 2016

This study was conducted to investigate the condition of frying oil used for frying chicken nuggets in a deep fryer. The acidification of the frying oils used, soybean oil (SB), canola oil (CA), palm oil (PA), and lard (LA), were determined as peroxide value, acid value, and fatty acid composition, after chicken nuggets were fried in them for 101 times. The acid value and peroxide value obtained were 5.14 mg KOH/g and 66.03 meq/kg in SB, 4.47 mg KOH/g and 71.04 meq/kg in CA, 2.66 mg KOH/g and 15.48 meq/kg in PA, and 5.37 mg KOH/g and 62.92 meq/kg in LA, respectively. The ranges of the major fatty acid contents were palmitic acid, 8.91-45.84%; oleic acid, 34.74-58.68%; linoleic acid, 10.32-18.65%; and stearic acid, 2.28-10.86%.Used frying oils for food except animal products have a legal limit for the freshness standard, set by the Food Codex regulations (AV<2.5, POV<50). Therefore, this study could help develop a freshness standard for frying oils used for animal products such as chicken nuggets. Based on the quality limits associated with food regulations stated, we suggested that the estimated frying times before acceptable freshness was exceeded were 41 for SB, 38 for LA, 53 for CA, and 109 for PA. This data may be useful in determining food quality regulations for frying oil used for animal products.

• Korean journal of food and cookery science
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• v.17 no.5
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• pp.478-482
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• 2001

This experiment was carried out to clarify the effect of frying temperature and gelatinization method on the quality of popped rice for Salyeotgangjung. Frying at 220$^{\circ}C$ or 230$^{\circ}C$ gave a good expansion and score of sensory evaluation. But the frying oil began to smoke at 230$^{\circ}C$. There was no significant difference in the quality of popped rices between the treatments of minimum gelatinization after washing rice and moderate gelatinization after soaking for 80 minutes at 30$^{\circ}C$. In conclusion, frying washed rice with minimum gelatinization at 220$^{\circ}C$ would be considered as the best method for making Salyeotganagjung.

• Journal of the Korean Society of Food Science and Nutrition
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• v.18 no.3
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• pp.247-254
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• 1989

In deep-fat frying, the fats and oils are used over and over again, and moisture and air are mixed in to the hot oil. Many reports related to these fats and oils have been established that thermal and oxidative decomposition products and polymers formed under the conditions of deep fat frying are harmful to health. This work was carried out with 3 domestic frying oils and 6 used oils commercially, and that there were difficulties in finding a good definition between fresh oil and used oil with adding unheated oil. As starting materials, commercially used soybean oil and rapeseed oil already passed over induction period in the lipids oxidation standard. From the qualitative point of view, they were inferior to domestic frying oils. Free fatty acid and peroxide value of heated oils were increased gradually by the time pass whereas iodine value were decreased. After adding unheated oil to the heated oil, these values were restored to that of initial levels. On the other hand, content of polar components in the heated oil were directly related to the heating time. This result showed that polar compounds may be a clear indicator of used oils. Fatty acid composition in the used oils, unsaturated fatty acids such as linoleic and linolenic acid decreased while saturated fatty acid content increased with heating.

• Journal of the Korean Society of Food Culture
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• v.23 no.4
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• pp.469-478
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• 2008

In this study, degree of rancidity and trans fatty acid formation were examined in fat and oils, including soybean oil (SB), canola oil (CA), corn germ oil (CO), olive oil (OL), palm oil (PO), and beef tallow (BT), during heating for 10-130 minutes at 160-200$^{\circ}C$. In order to determine the rancidity of the fat and oils, acid values (AV), iodine values (IV), viscosity, and color were measured. Changes in the amounts of fatty acids and the formation of trans fatty acids were measured using GC and HPLC. For all groups, AV increased, IV decreased, and coefficients of viscosity and color increased as the heating temperature and heating time increased, indicating there were positive correlations between the heating temperature and time and AV. In addition, all groups had similar amounts of trans fatty acids, with the exception of the beef tallow; however, its level only slightly increased with heating. The olive oil had the lowest trans fatty acid content and the lowest amount created by heating. The order of trans fatty acid amounts generated while heating was BT>PO>CO>CA>SB>OL. According to the study results, the deep frying temperature during cooking should be 160-180$^{\circ}C$ in order to reduce AV and the amount of trans fatty acids that are formed. In addition, it is better to remove beef tallow during cooking and avoid heating at high temperatures since it results in high levels of trans fatty acids. The correlation between the amount of trans fatty acids and AV was positive, while the correlation between the amount of trans fatty acids and IV was negative, indicating that AV and trans fatty acid levels increase while IV decreases as the deep frying temperature and time increase. From the results, it was found that reducing the deep frying temperature and time can lessen increases in AV and trans fatty acids, and decrease IV. Accordingly, to reduce AV and trans fatty acid formation, the ideal deep frying conditions would be to use olive oil or soybean oil rather than beef tallow or palm oil at a temperature of 160-180$^{\circ}C$.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.53 no.6
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• pp.834-841
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• 2020

Laver Pyropia sp. is the most exported seafood in Korea and is one of the most consumed edible seaweeds. The export of laver has been centered on seasoned laver products; of note, laver snack products coupled with rice papers or glutinous rice paste are becoming more popular in Western countries. These laver snacks are manufactured using a deep frying process. Therefore, the frying conditions affect the physicochemical and sensory characteristics of fried laver snacks. In this study, we optimized the deep-frying conditions for laver snacks with gelatinized rice dough using a response surface methodology. The frying temperature (X1, 190-220℃) and frying time (X2, 10-30 sec) were selected as independent variables; the dependent variables were the overall acceptance (Y1, points), hardness (Y2, N), and oil content (Y3, %). The optimal values of the frying temperature (X1) and time (X2) as per the overall acceptance (Y1) were 208℃ and 23.1 sec, respectively. The predicted overall acceptance (Y1=8.0 points), hardness (Y2=98.74N), and oil content (Y3=27.69%), were similar to the experimental values under the optimal conditions. Overall, the acceptance was inversely proportional to hardness; the decrease in hardness caused an increase in the crispiness of the laver snacks.