Question

Which oil contains more free fatty acids ?

• A. Safflower oil
• B. Mustard oil
• C. Rice bran oil
• D. Groundnut oil

Hint:

Rice bran requires immediate thermal stabilization (such as steaming or extrusion) right after milling to inactivate its highly active lipase enzyme and prevent the rapid buildup of free fatty acids in the oil.

Answer 1

The Correct Option is C

Step 1: Understanding the Concept:
Free fatty acids (FFAs) are produced when triglycerides are hydrolyzed by lipolytic enzymes (lipases) or high temperatures.
The FFA content is a key quality metric for crude oils because high levels increase refining losses and reduce shelf life.

Step 2: Detailed Explanation:
Rice bran is a by-product of the rice milling process that contains a highly active endogenous lipase enzyme.
During milling, the protective cell structure of the bran is disrupted, bringing these active lipases into direct contact with the lipids.
If the rice bran is not stabilized immediately using heat treatment (to denature the lipase), these enzymes hydrolyze the triglycerides at an extremely rapid rate.
This rapid enzymatic activity can increase the free fatty acid content of the bran by up to 1% per hour, and up to 5--10% within a single day.
As a result, crude rice bran oil typically has a much higher free fatty acid content (often ranging from 15% to 40%) than oils extracted from other oilseeds like safflower, mustard, or groundnut.
These other seeds do not have such highly active lipolytic systems and are typically processed with minimal delay.
Therefore, crude rice bran oil contains the highest amount of free fatty acids among the options.

Step 3: Final Answer:
Among the options, rice bran oil typically contains the highest concentration of free fatty acids due to the highly active lipase enzyme in rice bran.