市售蛋品之脂質組成及其氧化安定性   全文下載

Lipid Profile and Oxidative Stability of Commercial Egg Products

為瞭解各種市售蛋品之脂質品質，本研究將市售新鮮雞蛋、皮蛋、茶葉蛋、滷蛋、鐵蛋、鹹蛋等之蛋黃分別以Folch 試劑抽取脂質，同時自各地商場購得蛋黃油，均以TLC-FID法分析脂質組成、GC法分析膽固醇含量及脂肪酸組成、灰化定磷法測定磷脂質含量、並依中國國家標準（CNS）測定各脂質之酸價（Acid Value）、過氧化價、TBA值。結果顯示不同蛋品之脂質含量不一，其中以鐵蛋蛋黃脂質含量最高，約佔蛋黃重量之46%，皮蛋最低，約佔蛋黃重量之27%。各種蛋品之蛋黃脂質組成亦不同，磷脂質含量以新鮮蛋含量最高，約351 mg/g oil ，皮蛋含量最低，約175 mg/g oil ；膽固醇含量以新鮮蛋蛋黃油含量最高，為38.15 mg/g oil ，皮蛋蛋黃油含量最低，為28.51 mg/g oil 。脂肪酸組成顯示各種蛋黃油中均以18:1 、16:0 、18:2 之含量為最多。市售蛋品脂質酸價皆偏高，以鐵蛋為最高，達11.54 mgKOH/g oil，新鮮雞蛋最低，為0.30 mg KOH/g oil；TBA值以茶葉蛋最高，達2.73 mg malondialdehyde/kg oil ，生鮮蛋最低，為0.89 mg malondialdehyde/kg oil ；過氧化價均測不出。市售蛋黃油隨外觀形態之不同，其脂質組成及脂肪酸組成不一，在脂質組成方面，愈呈液體油狀者，其三酸甘油酯含量愈高、磷脂質含量愈低；反之，如愈呈固狀者，其磷脂質含量愈高、三酸甘油酯含量愈低。整體而言，三酸甘油酯、膽固醇及磷脂質分別約佔59-95% 、0.9-18% 以及1.8-33% 。脂肪酸組成顯示，磷脂質含量高的蛋油中16:1及18:1 含量較低， 18:0、20:4 及22:6 含量則較高。

This work was conducted to investigate the quality of lipids in various commercial egg products. Lipids of egg yolk were extracted from fresh egg, Pidan (preserved egg), tea egg, simmered egg, iron egg (deeply simmered and dried egg) and salted egg by Folch reagent, a mixture of chloroform and methanol at 2:1 volume ratio. The extracts and commercial yolk oil were analyzed to determine lipid profile, fatty acid composition, thiobarbituric acid value (TBA value), acid value and peroxide value. Results showed that the quality of yolk lipids was quite different. The lipid content ranged from 27% for Pidan to 46% for iron egg. Phospholipid content was highest in fresh egg (about 351 mg/g oil), while lowest in Pidan (about 175 mg/g oil). Cholesterol content of fresh egg yolk oil was the highest, about 38 mg/g oil, while the Pidan yolk oil contained the least cholesterol (28.51 mg/g oil). On the other hand, fatty acid compositions of all yolk lipids were consistent. Oleic, palmitic and linoleic acids were the three most abundant fatty acids. Acid and TBA values of lipids in processed eggs were generally higher than those in fresh eggs. Commercial yolk oil products also showed significant differences in lipid profile and fatty acid composition. The ranges of triglyceride, cholesterol and phospholipid contents were 59-95%, 0.9-18% and 1.8-33%, respectively. The yolk oils with higher liquid characteristic showed lower content of phospholipid and higher triglyceride content. Meanwhile, the yolk oil products with higher phospholipid content contained more 18:0, 20:4 and 22:6 fatty acids and less 16:1 and 18:1 fatty acids. Peroxide value was not detectable in all egg yolk extracts and yolk oils.