A Study on Beta-Carotene Contents of Egg Yolk In Relation To Storage Duration, Temperature and Its Correlation with Some Egg Quality Traits
Abstract
The experiment was conducted to investigate the effect of storage duration and temperature on β-carotene contents of egg yolk. Also, correlation between β-carotene contents of the eggs and some egg quality traits were examined. Both the storage duration and temperature were tested at three levels using a total of two hundred and seventy eggs laid by Isa Brown at fifty one week. The storage duration studied were 1 day, 7 days and 14 days, while the temperature regimes studied were 4 0C, 10 0C and 23 0C. Standard methods were used to determine the width, weight, length and shape index prior to storage. Spectrophotometer was used to determine the β-carotene contents of the eggs. Progressive decline in β-carotene contents of eggs was observed as the storage duration prolonged. Decline in β-carotene as temperature increased was negligible, which implies that storing eggs between 4 0C and 23 0C for a period of 14 days will not adversely affect the β-carotene content of the eggs. Slight negative correlation exists between β-carotene and egg weight, while strong negative correlations were observed between β-carotene and egg length, and β-carotene and egg width. Consequently, selecting for egg weight, egg length and egg weight entails regressive selection against β-carotene value of the egg.
Keywords
Download Options
Introduction
1.1 Background Egg yolk contains appreciable quantity of carotenoids which are highly bioavailable. The density of these carotenoids in egg yolks can be manipulated through the diet of laying hens. Beta-carotene is the most important group of carotene which serves as the primary source of vitamin A in the diet of man and farm animals (Olson, 1996). Vitamin A plays some key roles in both animal and human nutrition in that it is indispensable for goodnight vision, normal development of bone and teeth, development of healthy skin as well as mucous membrane (Maynard et al., 1979; Coutate, 1996; Geofrey, 1998; Ross, 1999; Thomas, 2006; Mahendra, 2017). The deficiency of this vitamin causes poor growth, weakness and decrease in egg production (Mahendra, 2017).
There are diverse sources of beta-carotene, and these sources include; sweet potatoes, carrots, kale, spinach, lettuce, fresh thyme, water squash, turnip greens, cantaloupe romaine etc. (Groff et al., 1995). Egg yolk, milk, and liver are the major animal sources of beta-carotene. In spite of these sources, deficiency in dietary beta-carotene is prevalence in both animal and human nutrition. The reason being partly due to the low level of concentrations of the beta-carotene in these nutrients and partly due to the unstable nature of beta-carotene.
Egg Yolk appears to be the most excellent source of beta-carotene. However, the concentration of beta carotene in egg yolk vary considerably. Okonkwo (2009) and Nnaji et al. (2013) reported discrepancies in beta content of egg yolk from local and exotic breeds of chicken. Plausibly, a number of factors may affect the beta carotene contents of egg yolk, though there is dearth of information to this effect. Consequently, this study is aimed at studying the effect of storage duration and temperature on beta-carotene contents of egg yolk. 1.2 Aim and Objectives The study is aimed at determining the effect of chicken’sstrain, storage duration and temperature on beta-carotene contents of egg yolk.
The specific objectives were to determine the: A. Effect of temperature on the beta-carotene content of egg yolk B. Effect of storage duration of B-carotene content of egg yolk.
C. Effect of storage and temperature interaction on B-carotene of egg yolk.
D. Correlation beta-carotene and other egg quality traits.
Conclusion
The results of this study shows that eggs of varied sizes, width, length that vary in composition of Beta-carotene are significantly affected at storing periods, thereby influencing the ultimate consumption of the eggs. Beta carotene content found in egg yolk is significantly reduced in quality at longer periods of storage.