• Journal of Food Hygiene and Safety
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• v.9 no.4
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• pp.199-203
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• 1994

The oxidation of cholesterol in tallow heated at three frying temperatures, 130, 150 and 18$0^{\circ}C$ was studied by assaying cholesterol oxidation products(COP)by GC-MS. The correlation between levels of COP and changes of physicochemical parameters (peroxide value, polymer, polar components and dielectric constant) in tallow heated were studied. As temperature increased, the amount of cholesterol was decreased proportionally with heating time. However, the levels of COP did not increase considerably with increased frying temperature. The rate of cholesterol disappearance was the greatest at 18$0^{\circ}C$ and the smallest at 13$0^{\circ}C$. Larger amounts of COP formed were found at 15$0^{\circ}C$ than at 18$0^{\circ}C$. The levels of COP formed in tallow heated showed highly correlation with(r=0.94, n=30, p<0.01) polymer, polar components and dielectric constant, respectively.

• Food Science and Preservation
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• v.8 no.3
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• pp.338-344
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• 2001

The oxidative stability of cholesterol in tallow heated at different frying temperatures (130$\^{C}$, 150$\^{C}$, and 180$\^{C}$) was studied by identifying cholesterol oxides by thin layer chromatography(TLC). And fatty acid compositions in tallow heated were also measured and compared with cholesterol oxides. Unsaturated fatty acid contents slightly decreased as the heating time increased, whereas saturated fatty acid contents increased This phenomenon became excessive especially by heating to higher temperature. It was found that RF value and spot color of the nonsaponifiable lipids from tallow heated on TLC analysis accorded with the synthetic cholesterol oxides in this experiment. Four kinds of cholesterol oxides were detected in tallow heated for 24 hours at three different temperatures. The oxides were identified as 7-$\alpha$-hydroxycholesterol, 7-$\beta$-hydroxycholesterol, 7-ketocholesterol and cholesterol epoxide. It was found that there was a little difference in oxidative pattern of cholesterol between several heating temperatures.

• Food Science and Preservation
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• v.8 no.3
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• pp.331-337
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• 2001

The oxidative stability of tallow heated was studied by different frying condition (temperature 130, 150, and 180$^{\circ}C$;heating time, each 10hours per day, total 240hrs). Changes of physicochemical parameters such as acid value, peroxide value, iodine value, dielectric constant, content of polar components and polymer, refractive index, smoke point, viscosity and color changes in tallow heated were also measured. Acid value, dielectric constant, refractive index, viscosity, and content of polar component and polymer increased as the tallow was heated longer, whereas iodine value and smoke point decreased and peroxide value was increased and decreased repeatedly. These parameters changed to a greater extent as the heating temperature went up. The color became darkened with the increase of red and yellow values during heating. The decree of coloration was proportional to heating temperature.

• Journal of Nutrition and Health
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• v.24 no.5
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• pp.408-419
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• 1991

The effects of various dietary fats on plasma lipids. liver lipids, and Plasma Peroxide levels were studied in rats fed for 6 wk with diets containing 15 wt% fat, as sesame oil. raw perilla seed oil. roasted perilla seed oil, heated perilla seed oil. mackerel oil or beef tallow. TBA values of these lipids during 4 wk storage, and linolenic acid contents of three kinds of perilla seed oil were also measured. Linolenic acid contents of raw perilla seed oil. roasted perilla seed oil and heated perilla seed oil were 62.3%, 61.6% and 53.1% respectively. Raw perilla seed oil showed the lowest rate of lipid peroxidation after 4 wk storage at 4$^{\circ}C$, and mackerel oil showed the highest peroxidation rate. The plasma cholesterol levels of rats consuming diets in which the carbohydrate was rice were not affected by n-3 PUFA. Rather, the degree of peroxidation seems to have a direct effect on cholesterol levels as shown by the hypocholesterolemic effect of raw perilla seed oil and beer tallow. However. the HDL-cholesterol level was greater in rats fed either roasted perilla seed oil or mackerel oil. Rats fed roasted perilla seed oil and raw perilla seed oil had lower levels of plasma triglycerides than rats fed beef tallow. In rats fed roasted perilla seed oil, the total lipid and cholesterol contents of liver were significantly lower than in those fed the other kinds of perilla seed oil. The plasma lipid peroxide levels were lower in rats fed either roasted perilla seed oil or beef tallow.

• Korean Journal of Food Science and Technology
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• v.5 no.1
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• pp.36-41
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• 1973

Chemical changes with time of frying-fats during the frying process (beef tallow with 0.01% BHA and 0.01% BHT, turnover rate 9%/hr and $140{\pm}10^{\circ}C$ temperature) of Ramyon on a commercial scale were studied. No significant changes of carbonyl value and peroxide value were noted up to 120 hrs. However, small increases in acid value, color and dimeric fatty acid were noted. Small decreases in iodine value and the content of unsaturated fatty acids were also observed. Under the experimental storage condition, when the stability of fats heated were compared to fresh fat, minor differences in carbonyl value and weight gain were noted. All of these demonstrated that frying-fats commercially used in Ramyon frying system were maintained in good quality during the frying process.