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

• Korean journal of food and cookery science
• /
• v.28 no.4
• /
• pp.443-450
• /
• 2012

This study was investigated the effect of an oil-water fryer on quality properties of deep frying oil used for chicken. The acid and conjugated dienoic acid values of frying oil using an oil-water fryer were lower than those using a deep fat fryer, whereas the iodine value of frying oil using an oil-water fryer was higher than that using a deep fat fryer. The peroxide values of frying oil did not increase with frying number. Frying oil with an oil-water fryer had lower palmitic acid, stearic acid and oleic acid, and higher linoleic and linolenic acid contents than those with a deep fat fryer. The contents of trans-fatty acids in frying oil using a deep fat fryer and oil-water fryer after frying 110 chickens were 0.75% and 0.47%, respectively. The benzopyrene contents of frying oil using a deep fat fryer and an oil-water fryer after frying 110 chickens were 2.20 and $1.61{\mu}g/kg$, respectively.

• Journal of the Korean Home Economics Association
• /
• v.19 no.2
• /
• pp.213-221
• /
• 1981

This theiss deals with the effects of addition of silicone oil to the polymerization and oxidation of frying oil in the practical deep fat frying process. The measurement of frying oil stability was carried out under various silicone oil content and compared with controlled frying process. In controlled frying process A.V., C.O.V., TBA, and contents of petroleumether insoluble fatty acids were increased as time was increased. It means thermal oxidized polymerization and hydrolysis of frying oil was occurred. When silicone oil was added to frying oil, it's thermal stability was better than that of the controlled oil and the degree of thermal stability was changed according to the contents of silicone oil. We obtained the highest degree of thermal stability when silicone oil was added 1ppm.

• Journal of the Korean Home Economics Association
• /
• v.24 no.4
• /
• pp.75-84
• /
• 1986

The followings are the results of the study on decomposition of oil during the process of frying hot-dogs with soybean oil. First, the oil was heated repeatedly for six days, four hours two session per day. Then the oil was observed when heated under identical condition except for the exclusion of the frying ingredients. And the oil itself was heated constantly for a period of 48 hours. 1. The AV and Carbonyl Value of all frying oils increased with each use (but the oil in which frying ingredients with all other oils) 2. All frying oils showed a tendency to increase initially, then decrease their POV and TBA Number during their heating process. 3. The IV of all oils showed a slight decrease except for oil with frying ingredients added, with showed a substantial decrease. 4. Oil with frying ingredients showed a substantial increase in its oxidized fatty acid level, and others showed a tendency to increase according to the frying time. Decomposition of soybe an oil during the process of frying hot-dogs was studied. Three treatment was performed first, the oil was heated (with hot-dogs) repeatedly four hours in each session, two sessions per day for six days. Second, the oil was heated without hot-dogs under identical condition, Third, the oil was heated constantly for 48 hours.

• Journal of the East Asian Society of Dietary Life
• /
• v.22 no.4
• /
• pp.527-534
• /
• 2012

This study investigated changes in the quality properties of deep frying oil and fried chickens according to frying number. Acid values of frying oil and fried chicken after frying 110 chickens were 2.27 and 1.90, respectively. The peroxide values of frying oil did not increase uniformly as frying number increased. Conjugated dienoic acid value of frying oil and fried chicken after frying 110 chickens were 0.70 and 0.44, respectively. Regarding the fatty acid composition after frying 110 chickens, linoleic and linolenic acids decreased, whereas palmitic, stearic, and oleic acids increased. Contents of trans fatty acids in frying oil and fried chicken after frying 110 chickens were 0.75% and 0.45%, respectively. Contents of benzo [a] pyrene in frying oil and fried chicken after frying 110 chickens were 2.20 and 2.19 ${\mu}g/kg$, respectively. The quality properties of frying oil and fried chickens significantly decreased after frying 60 chickens.

• Korean journal of food and cookery science
• /
• v.18 no.3
• /
• pp.340-348
• /
• 2002

Changes in the physicochemical properties of frying oil after single or repeated use in foodservice establishments were studied. The experiment was designed to simulate the practical frying practice based on a survey from the dieticians in the food service establishments. Used oils came from the single frying of mackerel and the sequential frying of 1) potato and mackerel, 2) battered pork and mackerel, and 3) potato, battered pork, and mackerel. The used oil samples were analyzed and compared with the fresh one. Oil quality parameters such as acid value, peroxide value, thiobarbituric acid value, iodine value, viscosity, and color were measured at each step of deep-fat frying. The physicochemical properties of the frying oils have been more or less affected by the frying conditions. However, the used oils resulted from the experimental trials were within the range of acceptance as indicated by the acid and peroxide values.

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

• Korean journal of food and cookery science
• /
• v.9 no.4
• /
• pp.293-297
• /
• 1993

This study aims to seek ways to improve frying stability of soybean oil which is widely used for deep frying while at the same time attempting to develop new frying oil and fat of high quality. Taking soybean oil as a control group, the study fried frozen potatoes with hydrogenated soybean oil with iodine value ranging from 60 to 110 for 15 hours. The test results showed that in frying stability, hydrogenated soybean oil with iodine value of 87 and 63 was superior to normal soybean oil and hydrogenated soybean oil with iodine value of 111(P<0.05). In sensory evaluation, however, no significant difference can be detected among groups(P>0.05). The correlation between physicoche-mical properties and sensory evaluation results was highest for smoke point and viscosity. This study concludes, therefore, that hydrogenated soybean oil with iodine value of 60~90 is better than normal soybean oil as deep-frying oil.

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

• Journal of the Korean Applied Science and Technology
• /
• v.10 no.2
• /
• pp.7-10
• /
• 1993

This study was carried out to investigate the effect of silicone oil on preventing deterioration of oil in frying potatoes. The results obtained are summarized as follows: 1. Frying potatoes in oil, the oil added silicone oil slowly increased acid value, dielectric constant and decreased smoke point as compared with the oil without silicone oil. In the early stage of frying, there was on difference in deterioration degree of the frying oil between 1ppm and 10ppm addition of silicone all. But as frying time prolonged, the higher silicone oil was added. the more stable in deterioration of frying oil. 2. When silicone oil was added at the level of $1{\sim}10ppm$ into the oil for frying potatoes. it was possible to prevent deterioration of the frying oil.