What Is Decomposition in Food?
4 Minutes
Food spoilage and preservation for kids: learn why bread gets moldy, why bananas blacken, and how to store food safely. An English science lesson.
- How fungus and bacteria spoil bread and other food
- Why bananas turn black and cheese dries up
- How boiling and refrigeration protect milk and bread
What this lesson teaches
Decomposition in food is the process where food breaks down and spoils, caused either by tiny living things called microorganisms or by natural physical and chemical changes. When food decomposes, it loses its freshness, changes its texture or color, and is no longer good to eat.
Microorganisms that spoil food
Many kinds of food decay because of microscopic organisms such as fungi and bacteria. When bread is left out, fungi begin to grow on it and appear as small green spots of mold. Even though mold starts as just a tiny patch, it continues to grow until it spoils the entire loaf. Not every microbe ruins food, however, because useful microbes like yeast are intentionally mixed into dough in small amounts to make bread soft.
Natural changes inside food
Food can also break down through internal chemical actions and moisture loss without foreign microbes attacking it first. Raw bananas contain substances called enzymes that help the fruit ripen. After the banana has ripened, these enzymes work from the inside and slowly turn the fruit black. In other foods, such as cheese, decomposition and loss of freshness happen when water content evaporates into the air, leaving the cheese completely dry and hard.
How low temperatures protect food
Temperature plays a major role in how quickly food breaks down. When milk or bread is left outside in warm room temperatures, microorganisms grow rapidly and cause the food to go bad. Placing food inside a refrigerator exposes it to cold, low temperatures. In this chilled environment, mold cannot grow on bread, and liquids like milk stay fresh for a much longer time.
Boiling and safe storage
- Boiling milk after buying it stops the many microorganisms naturally present in it from spoiling the liquid.
- Storing foods in tightly sealed containers or cans keeps them away from stray microorganisms that rest on surfaces like open plates.
- Keeping milk powder inside a tightly sealed container or a can stops microorganisms on open surfaces from spoiling it.