Abstract
The economical evaluation of eggs at retail stores of Kagoshima City is solely based on the visual inspection of size and shape. In general, eggs are classified into several grades, small, middle, large and so on, and their prices increase with their sizes. The author performed an experimental study to search for possible ways of economical shopping for consumers without reducing the nutritional level. Five eggs for each grade were used for this experiment. For each egg were measured the size (width and length) and weights of whole egg, egg yolk, egg white and eggshell. Concerning effects of weight of whole egg, it was found that eggs weighing 55-65g contain relatively large amount of egg yolk, whereas smaller eggs (40-50g) and larger eggs (over 70g) showed less of the yolk content. It was also shown that the shape of the egg is an important factor in deciding the quality of egg, i.e., the eggs of roundish shape gave a high edible portion and showed comparatively high yolk content. On the other hand, the eggs of elongated shape were rich in egg white but less in yolk content. Considering the fact that egg yolk contains large quantities of lipid, minerals and vitamins other than proteins, it is clear that egg yolk is a better nutrient than egg white. Therefore, it may be concluded that the most economical shopping can be achieved by selecting eggs with high yolk content. The relationship between egg size and sale price was also taken into consideration. Regardless of egg size, the relative content of edible portion was fairly constant (87-90%), and in general small eggs can be obtained at a cheaper rate than wholesale price, while large eggs are expensive mainly because large eggs are the main source of profits for retail stores. Therefore, it follows that for consumers, buying small eggs is the most advantageous.
