D20071029418 (ZARINA)

What Is It With Grade?

cuvettes with gelatin

Does the grade of an egg determine the protein content in it? To answer this question, we must care about the protein concentration in solutions (eggs). This is because, in my lab experiment objectives to determining the amount of protein biomolecules in a given solution is essential, to learn a method by which protein concentrations could be determined in sample of eggs and determine if absorbance levels correspond with protein concentrations in solution.

In this experiment, the spectrophotometer is an instrument that is used to measure the intensity of the color of a solution. When Biuret reagent reacts with peptide bonds it produces a violet color which will be detected by the spectrophotometer. The violet color indicates a positive Biuret test for protein, the more protein presents the darker the color. Hence, a appropriate blank is necessary to set the spectrophotometer reading at zero.

Various method can be used to determine the concentration pf protein in solution, for the example, Biuret assay, Lowry assay, and Bradford (Bio-Rad). The method chosen for this experiment was the Biuret Assay method. The concentration of protein is measured by the wavelength of 540nm, A540, by using spectrophotometer.First, we mix 1mg/ml of 0.50ml of gelatin (protein) with 2.5ml of Biuret reagent into the cuvette. Then, we repeat the first step by replacing 1mg/ml of 0.50ml of gelatin by 2mg/ml, 3mg/ml, 4mg/ml, 5mg/ml and 6mg/ml of 0.50ml of gelatin into other prepared cuvettes. Then we put each cuvette with different protein concentration into the spectrophotometer and the results are recorded in the table below.

Table 1: The absorbance of light at 540nm of different gelatin concentration

Table 2 : The absorbance of light at 540nm of different types of egg

Key:

Sample A : Grade A egg

Sample B : Grade B egg

Sample C : Grade C egg

Sample X : duck egg

Due to the equation y = 0.0747x – 0.0725

Calculation:

The comparison of protein concentration and prices among eggs.

From the experiment result, the concentration of protein in duck egg (sample X ) is highest between the others grade sample of eggs (A,B and C), which is has 12.429mg/L. The grade A’s egg has less 1.817mg/L concentration of protein than duct egg. In the market, I found that the cost for a duct egg is RM0.80. Wow..! it very expensive rather than other grade of eggs. The cost for a grade A’s is only RM0.34, grade B’s is RM0.32 and grade C’s is RM0.030. In average that mean, the cost for only a duct egg, we can get than two times of grade A’s, B’s or C’s egg.

Besides, the grade B’s has concentration of protein is 10.689mg/L. If compare the duct egg and the grade B’s egg, the duct egg has more 1.746mg/L concentration of protein than grade B’s egg. As we know, the cost for the grade B’ egg is RM0.32 and for the duct egg is RM0.080. So, I will prefer to buy grade B egg between both because it is cheaper and the protein content in both types of eggs just slightly different.

When I compare the protein content in grade B’s egg and grade C’s egg, I found that grade C egg only has a concentration of protein 0.825mg/L. While grade B’s egg has more 2.673mg/L of protein content compared to grade C’s egg. In market, a grade C egg is RM 0.30 while grade B’s egg is RM 0.32. Since grade B’s egg is has more protein content than grade C egg, so, between B and C I will choose to buy grade B egg.

In the other hand, when I compare the concentration of protein between grade A’s and grade B’s egg, the grade B’s egg has only higher 0.107mg/L than grade A’s egg. Since the cost different between grade A and B eggs is RM 0.02 but grade B egg has higher protein content. As a result, I will choose to buy grade B egg.

As a conclusion, the grade of an egg is not represent the real percentage of protein content that we can get from it for our healthy. As a wise consumer we should choose to buy grade B egg because it has more protein content 10.689mg/L, more valuable and has low of cost.