Food Chemistry

Rancidity

Deterioration of fats producing off-flavours. Hydrolytic rancidity releases free fatty acids by lipase or water; oxidative rancidity is a free-radical chain reaction with oxygen at unsaturated bonds.

Real-life application

The “off” smell and taste in old cooking oil, stale namkeen or biscuits made with old ghee — caused by fat breaking down over time.

Related terms

Peroxide value

Quality & Sensory

Milliequivalents of peroxide oxygen per kilogram of fat, measuring primary oxidation products (hydroperoxides).

Antioxidant

Food Chemistry

A substance that delays oxidative rancidity. Primary antioxidants (BHA, BHT, TBHQ, tocopherols) donate hydrogen to break the radical chain; secondary antioxidants (citric acid, EDTA) chelate pro-oxidant metals.

Free fatty acid

Quality & Sensory

Fatty acids released from triglycerides by hydrolysis, reported as a percentage or as acid value.

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