Question

'Churning of cream into butter is a process of phase reversal', this theory was given by

• A. Hooker and King
• B. Fisher and Hooker
• C. Fisher and Holt
• D. Walstra and Jenness

Hint:

The phase reversal theory explains churning as a transition from an oil-in-water (\(\text{O/W}\)) emulsion in cream to a water-in-oil (\(\text{W/O}\)) emulsion in butter.

Answer 1

The Correct Option is B

Step 1: Understanding the Concept:
The conversion of cream into butter is a physical process that alters the emulsion structure of milk fat.
Several theories have been proposed to explain the mechanism of butter formation during churning.

Step 2: Detailed Explanation:
The phase reversal theory of churning was proposed by Fischer and Hooker.
Cream is an oil-in-water (\(\text{O/W}\)) emulsion, where fat globules are dispersed in the continuous aqueous phase (milk serum) and stabilized by the milk fat globule membrane (MFGM).
According to this theory, the mechanical shear applied during churning disrupts the MFGM, releasing liquid fat.
This liquid fat binds the remaining fat globules together to form butter granules.
As churning continues, the emulsion undergoes phase reversal to become a water-in-oil (\(\text{W/O}\)) emulsion.
In this final state, butter exists as a continuous fat phase containing dispersed water droplets.
Other theories of churning include:
Rahn's foam theory, which suggests that foaming is necessary to concentrate fat globules at the air-water interface to facilitate clumping.

Step 3: Final Answer:
Therefore, the phase reversal theory of churning was proposed by Fischer and Hooker.