5Food Spoilage Overview

By:

Dr. Waleed FoadMSc.Public Health in Nutrition

Clinical Nutrition SpecialistEuropean Society of Gastrointestinal

Endoscopy (ESGE)Member of the American Society of

Nutrition Email: wfoad@outlook.com

Food SpoilageDefinition: Changes in food, through physical, chemical,

enzyme deterioration or micro-organism growth, that lead to the food becoming damaged, inedible or unsafe if eaten.

The food has visible signs of deterioration which makes it appear unpalatable or unpleasant.

The rate of deterioration depends on a variety of factors.

Contaminants may be already present in the food, e.g. salmonella in chicken or transferred to the food by humans, flies, rodents and other pests.

Conditions that could lead to Food Spoilage

1. Inadequate quantity of Food purchased (than required).

2. Inadequate quality of food and food ingredients purchased

3. Inadequate supervision of incoming Food items.

4. Inadequate supervision of Food-handling personnel.

5. Inadequate storage conditions and/or equipments.

Inadequate storage conditions and/or equipments

Examples: Dry storage: Irregular inspection and

maintenance of Storage areas, which leads to insanitary conditions. E.g.. Rodents, insects,....etc.

Frozen storage: failure to maintain refrigerators and freezers in good operating conditions.

Inadequate storage separation of different food items (e.g. Meats & vegetables, raw and cooked, frozen and dry,....etc)

Storage or Cross-contamination?

Causes of food spoilageFood spoilage is caused by two main factors,

namely;

Natural decay in foods:Definition: Natural process that leads to

spoilage of food as a result of: Moisture loss and/or The action of enzymes present naturally in

the food.

Contamination by micro-organisms e.g. Yeast, Bacteria

(Previously Discussed)

Natural decay in foodMoisture lossMostly occurs in fruit and vegetables which

contain large amounts of water. Fruits and vegetables continue to respire after

harvesting and therefore lose water through their leaves and skin.

The vegetable or fruit shrinks in size, its skin becomes wrinkled.

Moisture loss occurs in other foods like meat, fish, cheese, due to evaporation of water from the surface.

Natural decay in foodEnzyme action in the food

Through the action of enzymes presents in the food.

They speed up chemical changes that result in loss of flavor, color and texture.

As enzymes are mainly composed of protein, they are sensitive to heat. They are active in temperatures found in a kitchen on a warm sunny day.

They can remain very slightly active at very low temperatures such as those found in the freezer. This is why there is a limit to the time food can be stored in a freezer.

Natural decay in foodEnzyme action in the food

The activity of these enzymes stops when they are heated above 70 oC.

The activity of enzymes in food makes it easier for the micro-organisms responsible for food spoilage to enter the food.

Such enzymes speed up the process of decay by breaking down the tissues and components of the food in the various ways such as: Oxidation, Browning and Ripening.

Natural decay in foodEnzyme action in the food

Oxidation:When food comes into contact with oxygen, the

enzymes cause the destruction of certain nutrients e.g. vitamin c, thiamine and carotene.

Browning :Enzymes cause browning in certain foods the

moment they are exposed to air. When you cut or bruise food such as apple, the exposed surface will discolor and turn brownish due to the activity of enzymes.

Ripening.

Natural decay in foodEnzyme action in the food

Oxidation:Browning :Ripening:

Enzymes are involved in that process in certain foods such as fruits and vegetables.

Unripe bananas for example contain starch which is gradually converted to sugars, until the banana becomes very sweet, and its skin color changes from green to yellow. Eventually, the skin color changes to dark brown and it is no longer fit to be consumed.

Natural decay in foodEnzyme action in the foodBrowning and Ripening:

Reasons for keeping food items from spoilageSaving Food: Deterioration may cause food to be

wastedSaving Health: Contaminated food can cause

illness and in severe cases, food poisoningSaving MoneySaving nutritive valueStoring food items for lean seasons.

Food Spoilage

Questions?For Further Support:

Dr. Waleed FoadEmail: wfoad@outlook.com