Vi
ContRoL oF
MiCRooRGAniSMS
in FooDS
It is apparent from the materials presented in the previous chapters that although some microorganisms are desirable for the production of bioprocessed food, many are undesirable because they
can cause food spoilage and foodborne diseases. For efficient production of bioprocessed food, the
objectives are to stimulate growth and increase the viability of desirable microorganisms.
In contrast, with respect to spoilage and pathogenic microorganisms, the objective is to minimize their numbers or completely eliminate them from food. Several methods, individually or in
combination, are used to achieve these goals by (1) controlling access of the microorganisms in
foods, (2) physically removing the microorganisms present in foods, (3) preventing or reducing the
growth of microorganisms and germination of spores present in foods, and (4) killing microbial
cells and spores present in foods.
The influence of intrinsic and extrinsic factors necessary for optimum microbial growth and
the range in which each factor supports microbial growth have been discussed in Chapter 6. To
control growth and kill microorganisms in a food, some of these factors are used, but only beyond
the range that supports growth and induces germination of spores but can induce injury and death
(Chapter 10). Some of these controlling methods are discussed here.
Irrespective of the methods used, it is important to recognize that a control method is more
effective when a food has fewer microbial cells and when the cells are in the exponential growth
phase and are injured. Also, spores are more resistant than vegetative cells, and gram-negative
cells are generally more susceptible than gram-positive cells to many control methods. Finally,
bacteria, yeasts, molds, bacteriophages, and viruses differ in sensitivity to the methods used to
control them. Different species and strains of the same species also differ in sensitivity to these
control methods.
The following control or preservation methods are discussed in this section:
Chapter 31: Control of Access of Microorganisms: Cleaning, Sanitation, and Disinfection
Chapter 32: Control by Physical Removal
ContRoL oF
MiCRooRGAniSMS
in FooDS
It is apparent from the materials presented in the previous chapters that although some microorganisms are desirable for the production of bioprocessed food, many are undesirable because they
can cause food spoilage and foodborne diseases. For efficient production of bioprocessed food, the
objectives are to stimulate growth and increase the viability of desirable microorganisms.
In contrast, with respect to spoilage and pathogenic microorganisms, the objective is to minimize their numbers or completely eliminate them from food. Several methods, individually or in
combination, are used to achieve these goals by (1) controlling access of the microorganisms in
foods, (2) physically removing the microorganisms present in foods, (3) preventing or reducing the
growth of microorganisms and germination of spores present in foods, and (4) killing microbial
cells and spores present in foods.
The influence of intrinsic and extrinsic factors necessary for optimum microbial growth and
the range in which each factor supports microbial growth have been discussed in Chapter 6. To
control growth and kill microorganisms in a food, some of these factors are used, but only beyond
the range that supports growth and induces germination of spores but can induce injury and death
(Chapter 10). Some of these controlling methods are discussed here.
Irrespective of the methods used, it is important to recognize that a control method is more
effective when a food has fewer microbial cells and when the cells are in the exponential growth
phase and are injured. Also, spores are more resistant than vegetative cells, and gram-negative
cells are generally more susceptible than gram-positive cells to many control methods. Finally,
bacteria, yeasts, molds, bacteriophages, and viruses differ in sensitivity to the methods used to
control them. Different species and strains of the same species also differ in sensitivity to these
control methods.
The following control or preservation methods are discussed in this section:
Chapter 31: Control of Access of Microorganisms: Cleaning, Sanitation, and Disinfection
Chapter 32: Control by Physical Removal