Centrifugation: Acetic Acid and Centrifuge Tube

1541 Words Jun 25th, 2013 7 Pages
Experiment 2: Centrifugation

Title
Centrifugation of fresh milk and Acetic Acid

Objective(s):
1. To separate coagulated milk from mixture of fresh milk and Acetic Acid by centrifugation
2. To determine the relationship of speed of centrifugation with the coagulation of milk which separate from mixture.
3. To study the process of centrifugation

Introduction
Centrifugation is a process which materials suspended in a liquid medium undergo separation or concentrate due to the effect of gravity. Particles with different density and masses are settled at different rates in a tube which are response to gravity. Centrifuge is an instrument which can spin carrier vessels at high rotation speed and very high centrifugal force to allow
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Centrifuge is instrument that spin samples in high speed which can allow solution in centrifuge tube undergo centrifugation. The rotor is accelerated to a certain speed, and particles move at a rate which determine by size, shape and by the centrifugal force. Acetic acid is an organic compound with the chemical formula CH3COOH and it is a type of weak acid. 50% of Acetic acid was added in this experiment is to clot and precipitate out casein from milk by adjust the pH and isoelectric point of casein. The main protein in milk is casein. It is actually a mixture of three similar proteins, alpha, beta and kappa caseins which form a micelle. Alpha- and beta-casein are both insoluble in water and are solubilized by the micelle surrounding them. The kappa-casein which has a hydrophilic portion is responsible for solubilizing the other two caseins by promoting the formation of and stabilizing the micelles.

Calcium caseinate has an isoelectric point of pH 4.6. This means it is insoluble in solutions with a pH less than 4.6. The pH of milk is 6.6; therefore, casein has a negative charge…