Page 82 - Statistics presented by Dr. Sara Ismail Aborass

9/8/2023

Examination of oils and fats

Physical and chemical examinations serve as a mean of establishing
the purity of a given sample

Because they are used in food or in medication
Comparing the test values with documented ones.

A- Physical Examination

Physical parameters (constant values for each type of oil and fat)
• Melting point
• Specific gravity
• Refractive index

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B- Chemical examinations

Acid value

Number of mg of KOH required to neutralize the free fatty acid "FFA" in 1 g
of the substance
RCOOH + KOH → RCOOK + H2O (Neutralization reaction)

Determination
Dissolve a certain wt of the substance examined in ethanol/ether 1:1, titrate ≠

KOH, ph.ph ind (only indicator suitable for weak organic acids)
Significance
It is a measure of degree of hydrolysis of oil/fat → FFA (occur by time)
It is a test of freshness or edibility (suitable for eating) of the sample

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