Measure 100 ml, (7 tablespoons) of milk into a coffee mug. Place 1-1.5 inches of
ID: 1073468 • Letter: M
Question
Measure 100 ml, (7 tablespoons) of milk into a coffee mug. Place 1-1.5 inches of water in a saucepan (make sure the mug can stand up in the saucepan with water without spilling). Heat the water on the stove, but not hot enough to boil. Remove your warm water bath from live heat. Place the mug in the saucepan of warm water and heat. Remove the mug from the water bath and add about 30 ml. (2 tablespoons) of white vinegar to the warm milk. Gently stir the milk and vinegar by swirling in a circular motion. You should see a separation of the milk. Filter the coagulated suspension, which contains casein and butterfat. through two coffee filters (stacked one inside the other). Collect and save the filtrate (the liquid) in a jar or another coffee mug. Pour two approximate 10 ml, (each is about 2 teaspoons), portions of water through the coffee filter to rinse the gooey solid. Continue with the isolation of casein. Take a piece of aluminum foil big enough to cover the saucepan on the stove. You will be putting your casein/butterfat mixture on top of this aluminum foil so make sure you have enough foil so that you can bend some extra over the sides of the saucepan for stability. Gently scrape the precipitate (solid) onto the foil and spread it out a bit. Do not puncture the foil. Carefully place the foil over the pot of water and bend the edges down around the pot. Do NOT make an airtight seal. You need room for the steam to escape. Start heating the pot on the stove. As the healing progresses, water will separate front the solid and the precipitate will dry out. Use a wadded up paper towel to absorb the water. Carefully stir up the casein/butterfat precipitate with a spoon or rubber spatula to help it dry out. When the solids looks fairly dry. remove it from the heat. When it has cooled sufficiently to touch, remove the foil from the top of the saucepan and set it on the counter. Questions and Problems Describe the appearance and odor of the precipitate. Find another household product and approximately compare the amount of the precipitate formed to the amount of household product (i.e. the precipitate may be the size of 2 Tic-Tacs. 4 grains of rice, etc.).Explanation / Answer
When milk is heated with vinegar, it coagulates into solid precipitate which is filtered and dired over aluminium foil.
1. The appearence of precipitate is thick white solid granular initially which forms larger solid forms while heating for longer period. The odour is sweet.
2. egg white can also be precipitated easily by the same heating technique. The amount of precipitate formed in case of milk depends upon the initial casein concentration of milk and in egg white.