• Journal of the Korean Home Economics Association
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• v.11 no.4
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• pp.374-387
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• 1973

This work was carried out to investigate the changes of chemical and physical properties of frying oil, when it was used many times continuously without adding new oil. Four kinds of frying oil (soybean oil, rapeseed oil, shortening and crude lard) and slices of potato and Aji (kind of fish) were used in the experiment under the condition of home cooking. Obtained results were as in the followings. 1. Acid values and peroxide values of each frying oil were under the safety level (A. V = 1.5, Po. V = 50) except crude lard, when frying works were continuously repeated five times for 50 days. 2. Changes of saponification values of each frying oil showed a decreasing tendency except the crude lard. But in cases, stickiness or clothing of oil were not seen in frying even at the five times frying. 3. Changes of optical density of each frying oil showed a decreasing tendency in all cases, according to the times of frying, especially at the first time frying. 4. Maximum heights of the shamp of each frying oil and their shampholding activites when heated, were slowly increased according to the times of frying. 5. Without concerning the cooking condition (kinds of oil, cooking material and repeating times of frying) decrement of oil in once frying was almost exactly 20g per 150g. 6. Decrements of cooking material in all cases of frying showed almost constant values, potato to be 40% and Aji 20%. 7. Differences of smoke point between new and old oil (frying repeated 5 times) showed also almost constant values. Liquid oil (soybean oil and rapeseed oil) showed number (6-$10^{\circ}C$), on the contrally solid oil (shortening and crude lard) a high number (10-$25^{\circ}C$). 8. Results of public tastic for the frying products were almost good even in that of a low five times frying, but the products, of third time frying with crude lard were expressed as disagreeable.

• 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.

• Journal of the East Asian Society of Dietary Life
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• v.16 no.6
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• pp.717-723
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• 2006

Chemical characteristics of soybean oil after deep-frying with potato sticks (200 g, 10% w/w of soybean oil) were studied according to the 34 deep-frying times. After consecutive 34 deep-frying, total polyunsaturated FA contents was gradually decreased while the total saturated FA and trans FA were increased. Acid value and peroxide value were increased while iodine value decreased, respectively. The Hunter $L^{\ast}$ value decreased while each $a^{\ast}\;and \;b^{\ast}b$ value were gradually increased. Electronic nose equipped with 12 metal oxide sensors was used for the discrimination of odor pattern of frying oils against the times of deep-trying. The proportions of 1st and 2nd principal component analysis showed 75.97% and 21.23%, respectively. While 6 among total 12 sensors well responded to discrimination of odor in the repented frying oils, suggesting that the odor pattern of each oil after deep-frying would be discriminated against fresh soybean oil, especially after 14 times. From the results, electronic nose could differentiate the degree of quality deterioration of the repeated deep-frying oils.

• Journal of the Korean Society of Food Science and Nutrition
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• v.39 no.7
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• pp.1011-1017
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• 2010

Sunflower oil (SO), canola oil (CO) and frying oil (FO) were used as edible oils in this study. According to the frying number, the extracted oils from French fried potatoes were used as experimental samples. To investigate the relationship between the change of fatty acid composition and the stability of the lipid oxidation during frying, the changes of fatty acid composition and the degree of the lipid oxidation of samples were examined. Acid values and peroxide values were evaluated as the degree of lipid oxidation. The acid values of CO and FO were increased with the frying times. The increased acid values of CO and FO were 0.20 and 0.17 on the basis of initial value at 30 times, respectively, but the acid value of SO was lower than those of CO and FO. The peroxide values of the samples were not increased uniformly with the frying number. As the number of frying times was increased, the fatty acid composition of SO and FO were changed. Namely, the oleic acid composition was decreased, whereas the linoleic acid composition was increased with the number of frying times. The benzo(a)pyrene contents of the extracted oils from French fried potatoes did not change regularly as the frying times was increased.

• Korean journal of food and cookery science
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• v.16 no.4
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• pp.328-335
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• 2000

This study was investigated the effect of application methods of frying oil on the physicochemical properties of frying oil in the school foodservice. Frozen pork cutlet was fried for this study. The most frequent application methods of frying oil in school foodservice and treatments of this paper were as follows ; (A) use the frying oil (36ι) just one day(200ea.$\times$ 5times) (B) reuse the used oil(A method) once more adding 50%(18 ι) fresh oil after 3 or 5 or 7 days (C) reuse the used oil(A method) once more after 3 or 5 or 7 days. The major fatty acids of fresh oil were linoleic acid, oleic acid, palmitic acid, and linolenic acid in order to content. The viscosity of frying oil was increased gradually by increasing the number of frying times and storage period of frying oil after once used. Both redness and yellowness of frying oil showed similar trend to viscosity. As a result of this study, the application methods of frying oil in the school foodservice influenced on the physicochemical properties of frying oil, but acid and peroxide value were under the safety level of frying oil prescribed in the Health Social Affairs Ministry.

• Korean journal of food and cookery science
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• v.10 no.3
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• pp.301-307
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• 1994

Benzo(a)pyrene [B(a)P], one of the polycyclic aromatic hydrocarbons(PAHs) is know as a potent careinogen. As consumption of lipid food and fried food increases recently, the toxic effect of overheated lipid foods has report increasingly. This study was undertaken to measure the contents of B(a)P and other PAHs of fried chicken and frying oil. At the same time, the rancidities of frying oil and descarded oil were determined. B(a)P and other PAHs contents of all samples were measured by HPLC/UV method. The results obtained were as follows; B(a)P contents of fresh chicken and soybean oil were 0.073 and 0.146 ${\mu}$g/kg, respectively. During fried chicken at 180${\pm}$5$^{\circ}C$ and 200${\pm}$5$^{\circ}C$, B(a)P and PAHs contens decreased or increased In 20 times fried chicken, PAHs contents except Pyr and DMBA increased at 180${\pm}$5$^{\circ}C$ and PAHs contents except DMBA, DBA, and 3-MC increased at 200${\pm}$5$^{\circ}C$. In frying oils fried chicken, PAHs contents increased in 10 and 15 times frying oil at 180${\pm}$5$^{\circ}C$ and grew more increase and more increase during frying at 200${\pm}$5$^{\circ}C$. The changing pattern of PAHs contents of frying oils was remotely related that of rancidities of frying oils. In fried chicken, frying oils, and discarded oils obtained from fried chicken house at market, PAHs contents of fried chickens were lower than those of fried chicken cooked at laboratory but those of frying oils and discarded oils were higher than those of frying oils cooked at laboratory.

• Food Science of Animal Resources
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• v.40 no.5
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• pp.785-794
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• 2020

Food Codex regulations have set freshness limits for oils used to fry food, such as potato and fish products, and fried food itself; however, no such freshness limits have been set for meat products, such as sweet and sour pork. The freshness standard suggest that acid values (AVs) and peroxide values (POVs) for frying oil should be less than 2.5 and 50, respectively, whereas AVs and POVs for common fried food should be less than 5.0 and 60, respectively. Therefore, in this study, we investigate the effect of the number of frying cycles on oxidation-promoted changes in the oils used to fry sweet and sour pork and fried food itself during repeated frying over 10 d by determining their AVs and POVs, which were found to be highly correlated. Soybean, canola, palm, and pork lard oils could be reused approximately 37, 32, 58, and 87 times, respectively, to fry sweet and sour pork based on oil freshness, and 78, 78, 81, and 286 times, respectively, based on the freshness of fried food. Our data may help establish food-quality regulations for oils used to fry animal-based foods.

• 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.

• Korean Journal of Agricultural Science
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• v.42 no.4
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• pp.439-446
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• 2015

Kimbugak is one of Korea's traditional snacks made of laver. This study was conducted to investigate the physical drying and frying characteristics of kimbugaks made by a pasting & garnishing machine. The drying and frying characteristics should be analyzed to develop a continuous operation system for manufacturing kimbugak because kimbugak has a high moisture content after pasting process. Materials for pasting and garnishing on laver were rice gruel and sesame. The aluminum shelf with square hole was selected as a drying shelf. The recommended size of the square hole type was $1.5mm{\times}1.5mm$ because characteristics of deformation and easy separation from the shelf were excellent at the hole size. The drying time of 2 hours was also recommended with the drying temperature of $70^{\circ}C$ based on the test results such as dried condition (good), moisture conten t (3.7%), deformation (12.1 mm), and shrinkage rate (19.8%). As the frying conditions for dried kimbugaks, recommended oil temperature and frying time were $170^{\circ}C$, 15 seconds, respectively when corn oil was used. In the case of frying for undried kimbugaks, recommended oil temperature and frying time were $210^{\circ}C$, 2 - 3 minutes, respectively for improvement of work efficiency.