Purpose
The purpose of the experiment was to investigate the effect of the amount of drops of lemon juice added to skim milk on the mass of the formed curds.
Background Information
Milk curd is defined as the byproduct of the effects of acid and enzymes on milk protein and fat (Milk Chemistry). Fresh cows milk has a pH of between 6.7 and 6.5. When milk is acidified, the fat and proteins begin to curdle, or coagulate, causing the milk to separate into curds and whey. Curd contains most of the fat, casein protein and vitamin A of the original milk (Milk Chemistry). Milk consists of several different components; fat constitutes approximately 3 to 4 percent of the …show more content…
The casein proteins will coagulate at pH 4.6, and the whey proteins and remain in the milk solution at pH 4.6 (Milk Chemistry). In cow's milk, approximately 82% of milk protein is casein and the remaining 18% is whey protein. Out of the three major components in foods (carbohydrates, fats and proteins), proteins are the most unstable. As long as milk keeps its normal acidity level, the casein remains stable (Milk Chemistry). This is why when an acid such as vinegar or lemon juice is added to milk, casein, the primary protein in milk, it easily separated from the milk and …show more content…
This lab has concluded that as the number of drops of lemon juice added to the milk increased, the mass in grams of the formed curds increased. The hypothesis that if more drops of lemon juice are added to the skim milk, then the curd mass will increase was supported in his experiment. This is evident through the fact that in trial one, the curd weighed 8.6 grams when 10 drops of lemon juice were added to the milk. When 30 drops of lemon juice were added to the milk, a curd with a mass of 12.3 grams was produced. Scientific research concluded that as the pH drops in the milk, the casein molecules attract one another and curdle. Therefore, the curd mass increased due to an increase of the lemon juice concentration in the