Analysis and Formation of Trans Fatty Acids inFried FoodsAnalysis and Formation of Trans Fatty Acids inFried FoodsAnalysis and Formation of Trans Fatty Acids in Fried Foods

碩士 === 輔仁大學 === 食品營養學系 === 94 === Hydrogenated oil has been widely applied in baking products, frying products and margarine. Thus, trans fatty acids could be found in most of the food products. Epidemiological studies have shown that the intake of excessive amount of trans fatty acids may increase...

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Main Authors: Wen-Hung Liu, 劉文弘
Other Authors: Bing-Huei Chen
Format: Others
Language:zh-TW
Published: 2005
Online Access:http://ndltd.ncl.edu.tw/handle/86204889105344475215
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spelling ndltd-TW-094FJU002550042016-06-06T04:11:17Z http://ndltd.ncl.edu.tw/handle/86204889105344475215 Analysis and Formation of Trans Fatty Acids inFried FoodsAnalysis and Formation of Trans Fatty Acids inFried FoodsAnalysis and Formation of Trans Fatty Acids in Fried Foods 油炸食品中反式脂肪酸的分析與形成 Wen-Hung Liu 劉文弘 碩士 輔仁大學 食品營養學系 94 Hydrogenated oil has been widely applied in baking products, frying products and margarine. Thus, trans fatty acids could be found in most of the food products. Epidemiological studies have shown that the intake of excessive amount of trans fatty acids may increase the cholesterol content in blood and lead to occurrence of cancer. The objectives of this research were to develop an improved method for analysis of trans fatty acids and study their formation in fried oil and foods. Both chicken legs and French fries were fried in soybean oil or hydrogenated soybean oil at 160, 180 and 200℃, respectively. In addition, fresh soybean oil and hydrogenated soybean oil were heated separately at different temperatures for 24 h. In fried chicken legs and French fries, the trans fatty acids were extracted using a solvent system of chloroform and methanol(2:1, v/v), followed by saponification and methylation. However, for frying oils, a direct saponification and methylation method was employed. Both fried foods and oils were analyzed separately to study the formation of trans fatty acids and determine their contents by gas chromatography coupled with flame ionization and mass spectrometry detectors. Four types of columns, including DB-1 (J & W, 60 m × 0.32 mm I.D., 0.25 μm film thickness), INNOWax (Agilent, 30 m × 0.32 mm I.D., 0.25 μm film thickness), INNOWax (Agilent, 60 m × 0.32 mm I.D., 0.25 μm film thickness) and HP-88 (Agilent, 100 m × 0.25 mm I.D., 0.2 μm film thickness) were compared for their separation efficiency of trans fatty acids. Results indicated that a HP-88 column provided better separation than the other columns. The injector split ratio was 10:1, and the column temperature was 170℃ in the beginning, maintained for 24 min, increased to 220℃ at 7.5℃/min, to 230℃ at 10℃/min, and maintained for 5 min. A total of eight trans fatty acids were separated within 31 min. The trans fatty acids were not detected in fresh soybean oil even after heating at 160~200 ℃ for 24 h. Conversely, three trans oleic acids (C18: 1, Δ6t, Δ9t and Δ11t) and one trans linoleic acid (C18: 2, Δ9tΔ12 t) were found in unheated hydrogenated soybean oil. However, the hydrogenated soybean oil did not show any trans fatty acids formation after heating at 160~200℃ for 24 h. The amounts of trans fatty acids in the fresh soybean oil and hydrogenated soybean oil decreased both with increasing heating time and temperature, and reached a plateau at 200℃ for 24 h. Trans fatty acids were not detected in French fries fried in fresh soybean oil, but were found in those fried in hydrogenated soybean oil, probably because of absorption of oil by French fries during frying. However, no obvious trans fatty acids formation occurred during frying. For chicken leg meat, trans fatty acids did not form as well during frying in fresh soybean oil or hydrogenated soybean oil. Likewise, trans fatty acids were not detected in chicken leg skin fried with soybean oil but were present in chicken leg skin fried with hydrogenated soybean oil. All in all, the trans fatty acids may only be formed under drastic frying condition. Bing-Huei Chen 陳炳輝 2005 學位論文 ; thesis 248 zh-TW
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description 碩士 === 輔仁大學 === 食品營養學系 === 94 === Hydrogenated oil has been widely applied in baking products, frying products and margarine. Thus, trans fatty acids could be found in most of the food products. Epidemiological studies have shown that the intake of excessive amount of trans fatty acids may increase the cholesterol content in blood and lead to occurrence of cancer. The objectives of this research were to develop an improved method for analysis of trans fatty acids and study their formation in fried oil and foods. Both chicken legs and French fries were fried in soybean oil or hydrogenated soybean oil at 160, 180 and 200℃, respectively. In addition, fresh soybean oil and hydrogenated soybean oil were heated separately at different temperatures for 24 h. In fried chicken legs and French fries, the trans fatty acids were extracted using a solvent system of chloroform and methanol(2:1, v/v), followed by saponification and methylation. However, for frying oils, a direct saponification and methylation method was employed. Both fried foods and oils were analyzed separately to study the formation of trans fatty acids and determine their contents by gas chromatography coupled with flame ionization and mass spectrometry detectors. Four types of columns, including DB-1 (J & W, 60 m × 0.32 mm I.D., 0.25 μm film thickness), INNOWax (Agilent, 30 m × 0.32 mm I.D., 0.25 μm film thickness), INNOWax (Agilent, 60 m × 0.32 mm I.D., 0.25 μm film thickness) and HP-88 (Agilent, 100 m × 0.25 mm I.D., 0.2 μm film thickness) were compared for their separation efficiency of trans fatty acids. Results indicated that a HP-88 column provided better separation than the other columns. The injector split ratio was 10:1, and the column temperature was 170℃ in the beginning, maintained for 24 min, increased to 220℃ at 7.5℃/min, to 230℃ at 10℃/min, and maintained for 5 min. A total of eight trans fatty acids were separated within 31 min. The trans fatty acids were not detected in fresh soybean oil even after heating at 160~200 ℃ for 24 h. Conversely, three trans oleic acids (C18: 1, Δ6t, Δ9t and Δ11t) and one trans linoleic acid (C18: 2, Δ9tΔ12 t) were found in unheated hydrogenated soybean oil. However, the hydrogenated soybean oil did not show any trans fatty acids formation after heating at 160~200℃ for 24 h. The amounts of trans fatty acids in the fresh soybean oil and hydrogenated soybean oil decreased both with increasing heating time and temperature, and reached a plateau at 200℃ for 24 h. Trans fatty acids were not detected in French fries fried in fresh soybean oil, but were found in those fried in hydrogenated soybean oil, probably because of absorption of oil by French fries during frying. However, no obvious trans fatty acids formation occurred during frying. For chicken leg meat, trans fatty acids did not form as well during frying in fresh soybean oil or hydrogenated soybean oil. Likewise, trans fatty acids were not detected in chicken leg skin fried with soybean oil but were present in chicken leg skin fried with hydrogenated soybean oil. All in all, the trans fatty acids may only be formed under drastic frying condition.
author2 Bing-Huei Chen
author_facet Bing-Huei Chen
Wen-Hung Liu
劉文弘
author Wen-Hung Liu
劉文弘
spellingShingle Wen-Hung Liu
劉文弘
Analysis and Formation of Trans Fatty Acids inFried FoodsAnalysis and Formation of Trans Fatty Acids inFried FoodsAnalysis and Formation of Trans Fatty Acids in Fried Foods
author_sort Wen-Hung Liu
title Analysis and Formation of Trans Fatty Acids inFried FoodsAnalysis and Formation of Trans Fatty Acids inFried FoodsAnalysis and Formation of Trans Fatty Acids in Fried Foods
title_short Analysis and Formation of Trans Fatty Acids inFried FoodsAnalysis and Formation of Trans Fatty Acids inFried FoodsAnalysis and Formation of Trans Fatty Acids in Fried Foods
title_full Analysis and Formation of Trans Fatty Acids inFried FoodsAnalysis and Formation of Trans Fatty Acids inFried FoodsAnalysis and Formation of Trans Fatty Acids in Fried Foods
title_fullStr Analysis and Formation of Trans Fatty Acids inFried FoodsAnalysis and Formation of Trans Fatty Acids inFried FoodsAnalysis and Formation of Trans Fatty Acids in Fried Foods
title_full_unstemmed Analysis and Formation of Trans Fatty Acids inFried FoodsAnalysis and Formation of Trans Fatty Acids inFried FoodsAnalysis and Formation of Trans Fatty Acids in Fried Foods
title_sort analysis and formation of trans fatty acids infried foodsanalysis and formation of trans fatty acids infried foodsanalysis and formation of trans fatty acids in fried foods
publishDate 2005
url http://ndltd.ncl.edu.tw/handle/86204889105344475215
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