Cause and prevention of rancidity


It is a natural process that occurs when fats and oils are exposed to certain conditions such as oxygen, light, heat and moisture. There are two primary types of rancidity: oxidative rancidity and hydrolytic rancidity.

Oxidative rancidity: This type of rancidity occurs when fats and oils react with oxygen in the air, creating free radicals. Free radicals are highly reactive molecules that can initiate a chain reaction of oxidation, thereby breaking down the fatty acid chains in the fat or oil. Oxygen can enter the fat or oil through exposure to air or by the action of enzymes. Oxidative rancidity is accelerated by factors such as light, heat and the presence of certain metals such as iron and copper. It usually affects unsaturated fats and oils, which have double bonds in their fatty acid chains.

Hydrolytic Rancidity: Hydrolytic rancidity occurs when fats and oils react with water molecules, resulting in the breakdown of ester bonds that hold the fatty acid chains together. This breakdown leads to the release of free fatty acids. Hydrolysis can be catalyzed by an enzyme called lipase, which is naturally present in some foods, or by high temperatures during cooking processes such as deep-frying. Hydrolytic rancidity is commonly seen in high-moisture foods, such as fried snacks, baked goods, and mayonnaise.

To prevent rancidity, it is important to store fats and oils properly in airtight containers away from light, heat, and moisture. Manufacturers often add antioxidants such as vitamin E (tocopherol) or BHA/BHT (butylated hydroxyanisole/butylated hydroxytoluene) to food products to slow down the oxidation process and increase shelf life. Regular inspection and removal of expired or rancid oils and fats is also important to maintain food quality and safety.

When fats and oils present in food ingredients are oxidized by oxygen (air), their oxidation causes the products to have an unpleasant odor and taste. A condition produced by aerial oxidation of fats and oils in foods marked by an unpleasant odor and taste. 

Fats and oils spoil the prepared foods that are kept in them for a long time and make them unfit to eat. The specialty of stale food is that it gives an unpleasant smell and also has an unpleasant taste. that is called the rancidity of food.

The manufacturer of potato chips fills the plastic bags containing chips with nitrogen gas for prevention of rancidity
image by Pixabay

The development of rancidity of food can be prevented by the following methods

adding anti-oxidant- Anti-oxidant is such a substance which prevents oxidation by adding oxidant to the food, so the fats and oils present in it do not oxidize easily and hence do not get spoiled. So the food remains good to eat for a long time. Two common antioxidants used to prevent the development of rancidity in foods are
BHA (Butylated Hydroxy Anisole) and BHT (Butylated Hydroxy Toluene)

Rancidity can be prevented by packing foods containing fats and oils in nitrogen gas.The manufacturer of potato chips fills the plastic bags containing the chips with nitrogen gas (a nonreactive gas) to prevent the chips from oxidizing and becoming rancid.

Storing food in the refrigerator can slow down rancidity - the temperature inside the refrigerator is lower. When food is kept in the refrigerator, the oxidation of fats and oils in it slows down due to the low temperature. So, the development of rancidity due to oxidation is slow.

Rancidity can be prevented by keeping food in airtight containers
When food is stored in airtight containers, there is little contact with oxygen, slowing down the oxidation of fats and oils in the food and therefore slowing down the development of rancidity.
Rancidity can be prevented by keeping food away from light. In the absence of light, the oxidation of fats and oils present in the food is slowed down and thus the development of rancidity is slowed down.

To prevent rancidity in food products, there are some key measures that you can adopt:

Proper storage: Store fats and oils in airtight containers to limit exposure to oxygen. Make sure containers are tightly sealed after each use. Store these containers in a cool, dark place, away from direct sunlight and sources of heat.

Refrigeration: Refrigerate or freeze fats and oils, the low temperature helps slow the oxidation process and increase their shelf life.

Avoid exposure to moisture: Keep fats and oils away from sources of moisture and water, as hydrolytic rancidity occurs in the presence of water.

Proper packaging: When buying oils and fats, choose products in dark colored or opaque containers. This helps protect them from exposure to light, which can promote rancidity. Transparent containers allow light to pass through, which can speed up the oxidation process.

Limit air exposure: Minimize exposure to air as much as possible when using oils and fats. Open containers only when necessary and close them immediately after use. When filtering the oil into smaller containers, try to limit the amount of time it is exposed to air.

Antioxidants: Consider using oils and fats that contain natural antioxidants, such as vitamin E (tocopherol), as they can help slow down the oxidation process. Look for products with added antioxidants or that are labeled as "high in antioxidants."

Proper food handling: When cooking with oil, avoid over-heating them as excessive heat can increase rancidity.

Regular inspection: Check oils and fats regularly for signs of rancidity, such as unpleasant odor, taste, or changes in color and consistency.

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