Effects of microorganisms on food

Foods undergo deterioration to varying degrees in organoleptic properties, nutritional value, safety and esthetical appeal.  The term food deteriorations, is often associated with advanced spoilage.

Bacteria, molds and yeasts are the main causes of the spoilages of unpreserved foods, with bacteria playing the major role in the spoilage of meats, poultry, dairy, and fish products.

Mold and yeast play the major role in the spoilage of fruits and vegetables. The changes in foods due to microbial action can be classified into two types: undesirable changes and desirable changes.

These microorganisms do not cause disease but they spoil food by growing in the food and producing substances which alter the color, texture and odor of the food, making it unfit for human consumption.

All bacteria associated with foods are small. Most are of the order of one to a few micrometers in length and somewhat smaller than this in diameter. All bacteria can penetrate the smallest openings; many can pass through the natural pores of an egg shell once the natural bloom of the shell is worn.

Yeasts are somewhat larger, of the order of 20 um or so in individual cell length and about a third this size in diameter.

Typically, the effects of temperature, pH, and the acidulants, water activity and the humectants, oxygen availability, redox potential and identity and concentration of inhibitory agents are among the variables that must be considered when assessing whether microorganisms will pose a problem in particular food system.
Effects of microorganisms on food

The meaning of food spoilage

The quality of food can be adversely by physical, chemical, biochemical and microbiological processes. Food spoilage is defined as ‘the change in the characteristics of food that makes it unacceptable’. It refers to food that appears unpalatable such as sour milk or a brown apple.

The cause of these changes can be attributed to physical or biological process.

Generally, a food is considered spoiled when it is no longer acceptable to the consumer. The worst case of spoilage is when it becomes a food safety issue, where the food product may cause the consumer illness or even death.

Less serious cases of food spoilage can simply be that the color, flavor, texture or aroma of the food has deteriorated to the point that is no longer acceptable.

It may due to a number of causes:
*Insect damage
*Physical injury due to bruising, pressure freezing, drying and radiation
*The activity of indigenous enzymes in animal and plant tissues
*Chemical changes not induced by microbial or naturally occurring enzymes
*The activity of bacteria, yeasts and moulds

Microorganisms are the major cause of the spoilage of food and are responsible for these chemical changes. Fresh fruits and vegetables easily get contaminated by microorganisms, present in soil, water, air and other environmental sources and various plant pathogens.

To prevent food getting spoiled is it important to know how and why food gets spoiled, which are the foods that are likely to spoil rapidly, what are the factors that bring about quicker spoilage and how food can be prevented from getting spoiled.
The meaning of food spoilage