The aim of this study was to investigate and compare the physicochemical properties, such as the technical use of animal fat and the nutritional value, of hen egg-yolk oils based on different laying periods. Hen egg-yolk oils were extracted using solvents from double yolk (18 weeks), guide (24 weeks), pullet (30 weeks), and jumbo (80 weeks) eggs. Weight and fat ratios of the hen eggs, as well as the free fatty acid content, peroxide value, iodine value, oxidative stability, fatty acid composition, and sterol composition of the yolk oils were determined in the study. According to the results of the analyses of white-shell eggs, the fat contents of the boiled egg (both the white and yolk), fat contents of the egg yolk, free fatty acid values, peroxide values, and oxidative stability values were between 7.85 and 11.25%, 18.58 and 34.71%, 1.03 and 2.32%, 8.58 and 9.54 meq O2/kg, and 8.0 and 10.2 h, respectively. Palmitic, stearic, oleic, and linoleic acids were determined at the highest levels in the fatty acids. Cholesterol and campesterol were the two dominant sterols among the 10 sterol components. We determined that the physicochemical properties of white-shell egg-yolk oils varied according to different laying periods in terms of animal fat, and based on the 80-week laying period, egg-yolk oils were suitable for both internal and external consumption; the most ideal egg-yolk oils were extracted during the 30-week (pullet) period.
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