Food microbiology
Food microbiology is the study of microbial activities in food. This means that microorganisms
and human are in direct competition for the nutrients in food and the fast rate of microbial
growth gives them an advantage. Food become contaminated with microbes along the route of
procurement, processing or preparation. The detection and control of pathogens and food
microorganisms are important aspect of Food microbiology. Ruining food sources by infecting
and destroying plants and animals which are the major human food sources is the primary role
of microorganisms in nature. Because food are nutrients rich, it forms an excellent environment
for the growth of microorganisms.
Microbial growth
Microbial growth is controlled by two divided factors
1. Intrinsic factors: This is achieved through food related factors that includes :
○ Nutrient content / food composition: The nutrient content of food determines
the rate of microbial growth in the food e.g carbohydrates this is most critical
intrinsic factor affecting microbial growth, proteins experience more bacterial
growth which results in the production of variety of foul odour,the foul smell is as
a result of anaerobic breakdown of protein that yield foul smelling amine
compound as a result of microbial activity. Carbohydrates experiences fungi
rather than bacteria as the predominant organisms.
○ PH : the ph value of fruits and vegetables determines the speed of it's spoilage
and yeast production. Most bacteria grow best at neutral or weakly alkaline PH
usually between 6.8 and 7.5 while some grow within a narrow range of 4.5 and
9.0.
○ Moisture content: the rate of growth of microorganisms can be determined also
by the level of water activity present in such food, when food are dried it makes it
difficult for microorganisms to grow
○ Antimicrobial constituents: Antimicrobial substances in food inhibit microbial
growth. Various food have inherent antimicrobial substances that prevent
microbial attack.
○ Physical / biological structure of food: this can affect the extent of spoilage,
things like covering of some food provides excellent protection against the entry
and damage of spoilage organisms.
2. Extrinsic factors: These includes environmental factors which includes :
○ Temperature: microorganisms can grow over a wide range of temperature. The
growth of microorganisms is affected by the environmental temperature, various
microorganisms are able to grow at certain temperature and not others. on basis
of temperature requirements, Microorganisms can be grouped into the following
i. Psychrotophs microorganisms: these grows best at about 20°c but
also down to 10°c in unfrozen media. Psychrophilic bacteria can cause
food spoilage at low temperature. It includes several organisms found in
Food microbiology is the study of microbial activities in food. This means that microorganisms
and human are in direct competition for the nutrients in food and the fast rate of microbial
growth gives them an advantage. Food become contaminated with microbes along the route of
procurement, processing or preparation. The detection and control of pathogens and food
microorganisms are important aspect of Food microbiology. Ruining food sources by infecting
and destroying plants and animals which are the major human food sources is the primary role
of microorganisms in nature. Because food are nutrients rich, it forms an excellent environment
for the growth of microorganisms.
Microbial growth
Microbial growth is controlled by two divided factors
1. Intrinsic factors: This is achieved through food related factors that includes :
○ Nutrient content / food composition: The nutrient content of food determines
the rate of microbial growth in the food e.g carbohydrates this is most critical
intrinsic factor affecting microbial growth, proteins experience more bacterial
growth which results in the production of variety of foul odour,the foul smell is as
a result of anaerobic breakdown of protein that yield foul smelling amine
compound as a result of microbial activity. Carbohydrates experiences fungi
rather than bacteria as the predominant organisms.
○ PH : the ph value of fruits and vegetables determines the speed of it's spoilage
and yeast production. Most bacteria grow best at neutral or weakly alkaline PH
usually between 6.8 and 7.5 while some grow within a narrow range of 4.5 and
9.0.
○ Moisture content: the rate of growth of microorganisms can be determined also
by the level of water activity present in such food, when food are dried it makes it
difficult for microorganisms to grow
○ Antimicrobial constituents: Antimicrobial substances in food inhibit microbial
growth. Various food have inherent antimicrobial substances that prevent
microbial attack.
○ Physical / biological structure of food: this can affect the extent of spoilage,
things like covering of some food provides excellent protection against the entry
and damage of spoilage organisms.
2. Extrinsic factors: These includes environmental factors which includes :
○ Temperature: microorganisms can grow over a wide range of temperature. The
growth of microorganisms is affected by the environmental temperature, various
microorganisms are able to grow at certain temperature and not others. on basis
of temperature requirements, Microorganisms can be grouped into the following
i. Psychrotophs microorganisms: these grows best at about 20°c but
also down to 10°c in unfrozen media. Psychrophilic bacteria can cause
food spoilage at low temperature. It includes several organisms found in
