Alteration of membrane permeability: The plasma membrane of microorganisms, located in the cell wall, is the target of many antimicrobial agents. This membrane actively regulates the passage of nutrients into the cell and the elimination of waste from it. Damage to lipids or proteins of the plasma membrane by antimicrobial agents causes cell contents to leak into the medium and this interferes with cell growth.

Damage to proteins and nucleic acids: For a protein to be functional it needs to be in its tertiary structure at least, this is made up of hydrogen bonds, which are susceptible to breaking with heat or certain chemicals; The breaking of these bridges results in the denaturation of the protein. Similarly, covalent bonds, although stronger, are also targets of antimicrobial agents.

The nucleic acids DNA and RNA are those that carry the genetic information of the cell. Damage to these by heat, radiation, or chemicals is frequently lethal to the cell. The cell cannot replicate and cannot have its normal metabolic functions such as enzyme synthesis.

The high temperatures at which autoclaves operate eliminate all types of microbes and bacteria, including spores.

Contenido

Existen varios métodos de esterilización, detallados a continuación.[1]​[2]​.

Chemical methods

Chemical sterilization methods are those that involve the use of substances lethal to microorganisms, such as ethylene oxide and hydrogen peroxide.

The use of this method is very limited for the Food Industry but widely used in other industries such as pharmaceuticals.

Physical methods

Physical methods are those that do not involve the use of substances lethal to microorganisms, but rather physical procedures such as ionizing radiation, heat or filtration of solutions with membranes that prevent the passage of microorganisms, including viruses.

The most used method in this category is heat, which kills microorganisms by denaturing enzymes; the resulting change in the three-dimensional shape of the proteins inactivates them. Heat resistance varies among different microorganisms; This difference can be expressed as the thermal death point (TDP), which is defined as the lowest temperature at which all microorganisms in a liquid suspension will be eliminated in 10 minutes.

Another factor that must be considered in a sterilization is the time required. This can be expressed as the thermal death time (TMT), which is the minimum time for all bacteria in a particular liquid culture to be killed at a given temperature.

Both PTM and TMT are useful guides that indicate the severity of treatment required to kill a given bacterial population.

Decimal reduction time (TRD, or D value) is the third concept related to bacterial heat resistance. TRD is the time, in minutes, in which 90% of a bacterial population at a certain temperature will be killed.

Heat treatments, in short, are methods of preserving food.

Thermal methods

Thermal methods usually encompass all procedures that have among their purposes the destruction of microorganisms by heat. The methods are both pasteurization and sterilization, whose main purpose is microbial destruction, as well as blanching and cooking, processes in which a certain reduction of the microbial flora is also achieved, but whose main objectives are the variation of physical properties.

The temperature and pressure conditions of a steam sterilization process in an autoclave range from 121 °C to 134 °C and 275-350 kPa "Pascal (unit)"). For the treatment of hospital waste, operation times between 20 and 30 minutes are used. The autoclave sterilization method uses microbiological tests, which are entered within the operation cycle and subsequently, through an incubator, the aim is to detect if there is growth of microorganisms. One of the microorganisms used in these tests is Bacillus stearothermophilus.

Sterilization temperatures range from 121 °C to 180 °C, taking into account the sterilization times for each case.[4]​.

In scientific laboratory research, it is mainly used to eliminate microorganisms from work elements, thus avoiding contamination of the sample, containers and work material.

In the food industry it is used to increase the shelf life of food. The most common sterilized foods are canned.

It is also used to preserve and extend the life of books, furniture, works of art and other goods.

In hospitals it is mainly used to eliminate pathogens from reusable surgical instruments.

Manufacturers of medical devices sterilize the products so that they can be used aseptically in a surgical or laboratory procedure by healthcare professionals.

In the treatment of hospital hazardous waste, high-efficiency sterilization is used in order to eliminate all pathogenic microorganisms and thus reduce the associated infection risks.

Alteration of membrane permeability: The plasma membrane of microorganisms, located in the cell wall, is the target of many antimicrobial agents. This membrane actively regulates the passage of nutrients into the cell and the elimination of waste from it. Damage to lipids or proteins of the plasma membrane by antimicrobial agents causes cell contents to leak into the medium and this interferes with cell growth.

Damage to proteins and nucleic acids: For a protein to be functional it needs to be in its tertiary structure at least, this is made up of hydrogen bonds, which are susceptible to breaking with heat or certain chemicals; The breaking of these bridges results in the denaturation of the protein. Similarly, covalent bonds, although stronger, are also targets of antimicrobial agents.

The nucleic acids DNA and RNA are those that carry the genetic information of the cell. Damage to these by heat, radiation, or chemicals is frequently lethal to the cell. The cell cannot replicate and cannot have its normal metabolic functions such as enzyme synthesis.

The high temperatures at which autoclaves operate eliminate all types of microbes and bacteria, including spores.

Contenido

Existen varios métodos de esterilización, detallados a continuación.[1]​[2]​.

Chemical methods

Chemical sterilization methods are those that involve the use of substances lethal to microorganisms, such as ethylene oxide and hydrogen peroxide.

The use of this method is very limited for the Food Industry but widely used in other industries such as pharmaceuticals.

Physical methods

Physical methods are those that do not involve the use of substances lethal to microorganisms, but rather physical procedures such as ionizing radiation, heat or filtration of solutions with membranes that prevent the passage of microorganisms, including viruses.

The most used method in this category is heat, which kills microorganisms by denaturing enzymes; the resulting change in the three-dimensional shape of the proteins inactivates them. Heat resistance varies among different microorganisms; This difference can be expressed as the thermal death point (TDP), which is defined as the lowest temperature at which all microorganisms in a liquid suspension will be eliminated in 10 minutes.

Another factor that must be considered in a sterilization is the time required. This can be expressed as the thermal death time (TMT), which is the minimum time for all bacteria in a particular liquid culture to be killed at a given temperature.

Both PTM and TMT are useful guides that indicate the severity of treatment required to kill a given bacterial population.

Decimal reduction time (TRD, or D value) is the third concept related to bacterial heat resistance. TRD is the time, in minutes, in which 90% of a bacterial population at a certain temperature will be killed.

Heat treatments, in short, are methods of preserving food.

Thermal methods

Thermal methods usually encompass all procedures that have among their purposes the destruction of microorganisms by heat. The methods are both pasteurization and sterilization, whose main purpose is microbial destruction, as well as blanching and cooking, processes in which a certain reduction of the microbial flora is also achieved, but whose main objectives are the variation of physical properties.

The temperature and pressure conditions of a steam sterilization process in an autoclave range from 121 °C to 134 °C and 275-350 kPa "Pascal (unit)"). For the treatment of hospital waste, operation times between 20 and 30 minutes are used. The autoclave sterilization method uses microbiological tests, which are entered within the operation cycle and subsequently, through an incubator, the aim is to detect if there is growth of microorganisms. One of the microorganisms used in these tests is Bacillus stearothermophilus.

Sterilization temperatures range from 121 °C to 180 °C, taking into account the sterilization times for each case.[4]​.

In scientific laboratory research, it is mainly used to eliminate microorganisms from work elements, thus avoiding contamination of the sample, containers and work material.

In the food industry it is used to increase the shelf life of food. The most common sterilized foods are canned.

It is also used to preserve and extend the life of books, furniture, works of art and other goods.

In hospitals it is mainly used to eliminate pathogens from reusable surgical instruments.

Manufacturers of medical devices sterilize the products so that they can be used aseptically in a surgical or laboratory procedure by healthcare professionals.

In the treatment of hospital hazardous waste, high-efficiency sterilization is used in order to eliminate all pathogenic microorganisms and thus reduce the associated infection risks.