Nutritional values of the lipid composition of the free-range chicken eggs

Abstract

Poultry eggs are eaten in most areas of the world with fewer social taboos associated with them than pigs and cattle. The most commonly used bird eggs are those from chicken. In Nigeria, the domestic foul dominates the poultry industry. Of the 120 million indigenous poultry population in Nigeria, the domestic fowl constitutes about 91 % of this. For this reason, the present work tried to evaluate the nutritional levels of the lipid composition of the free-range fertilized cooked chicken eggs. Five eggs were involved in the study and they were collected at once. The following experimental procedures were carried out on the yolk and the albumen using standard analytical methods: crude fat determination, preparation of methyl esters and fatty acid analysis. Also determined was the quality assurance of the determinations to ensure their accuracies, calculation of uncertainty interval percentage (UIP) particularly for the fatty acid values. Statistical evaluations carried out included: linear correlation coefficient (rxy), coefficient of determination (rxy 2 ), linear regression coefficient (Rxy), coefficient of alienation (CA) and index of forecasting efficiency (IFE). The study reports the nutritional values of the lipid composition of the free-range chicken eggs analyzing separately the yolk and the albumen. The yolk was 32.8 % of the total egg weight while the albumen was 53.8 %. The total crude fat in yolk was 22.9 g/100 g whilst it was 0.001 g/100 g in albumen. The total fatty acid in yolk was 19.0 g/100 g; it was 0.00083 g/100 g in albumen. The SFA level was 35.0 % in total fatty acids in yolk; it was 31.8 % in albumen. Total monounsaturated fatty acids (MUFA) in yolk was 43.5 % but 42.9 % in albumen. Total n-6 PUFA was 21.8 % in yolk and 25.2 % in albumen. The PUFA/SFA was 0.62 in yolk and 0.79 in albumen. Lecithin was high in yolk [115 mg/100 g; 46.0 %] but at trace level [23.3e-3 mg/100 g; 63.1 %] in albumen. Sterol was not detected in the albumen but total sterol in the yolk was 386 mg/100 g having cholesterol level of 86.3 mg/100 g (22.4 %). The levels of MUFA + PUFA in yolk was 65.3 % and 68.1 % in albumen showing that the chicken egg could be classified as being made up majorly of unsaturated oil. Free-range laying hens are given outdoor access instead of being contained in crowded cages; this gives them wide range of various feeding opportunities. This report showed the free-range chicken eggs yolk to be far more concentrated in crude fat; total fatty acids; SFA; MUFA; n-6 PUFA; high PUFA/SFA; high lecithin; high cephalin; high stigmasterol and cholesterol than the corresponding albumen. The cholesterol level was also below the average recommended level.