Moist heat sterilisation

• What is the temperature range for moist heat pasteurisation?

  60-80°C
• What is the boiling point for heating with a bactericide?

  100°C
• What is the wet process autoclave temperature?

  100°C
• Under what condition is moist heat effective for sterilisation?

  Only under pressure
• How does moist heat kill cells?

  By temperature increase and hydration change
• What is an autoclave compared to?

  A pressure cooker
• What do steam processes in an autoclave maintain?

  Constant pressure and temperature
• What happens to the steam if the temperature is preserved in an autoclave?

  It enters a superheated vapor phase
• What is the superheated liquid phase in an autoclave composed of?

  Small water droplets held in suspension
• What occurs if the temperature decreases in the dry saturated explosion phase?

  It will condense
• What factors are important in moist heat sterilisation?

  Heat release, hydration, and penetration
• What is sensible heat?

  Heat exchanged that results in a change in temperature
• What happens when latent heat is exchanged?

  It results in a change of physical state without a change in temperature
• What does superheat release?

  Only sensible heat
• What does superheat do in terms of condensation?

  It decreases condensation and only releases sensible heat
• What does dry saturated heat release?

  Both sensible and latent heat
• What is the effect of dry saturated moist heat on hydration?

  It leads to hydration and rapid heat transfer
• What does superheated dry heat cause?

  Oxidation and slower heat transfer
• What is the role of penetration in sterilisation?

  It allows for rapid penetration and condensation
• What happens during rapid penetration in dry saturated heat?

  Condensation occurs, leading to volume contraction and sealing
• What is the effect of poor penetration in superheated steam?

  It results in no condensation and no vacuum
• What is an option for autoclaving?

  Portable bench-top autoclave
• How does a portable bench-top autoclave compare to a domestic pressure cooker?

  It is similar in function
• What type of autoclave is used for large scale gravity displacement?

  Porous food autoclave (vacuum-assisted)
• What is a benefit of a benchtop autoclave?

  It is easy to use and works well per batch
• What happens to temperature, pressure, and steam in an autoclave?

  They remain on the boundary phase
• What is the efficiency of an autoclave affected by?

  The size of the vessel due to heat loss
• What do large scale autoclaves use to avoid heat loss?

  Separate steam generators
• How does gravity displacement work in an autoclave?

  Steam is added from the top while air is removed from the bottom
• What is the effect of air in lab media during autoclaving?

  It produces pressure that may not be reusable for porous loads
• What is a porous load in the context of autoclaving?

  Materials that require air removal before steam exposure
• What is an example of a porous material used in autoclaving?

  Dressings
• What are the stages of generation in autoclaving?

  Air removal, steam admission, heating, and drying
• What is the purpose of air balancing in autoclaving?

  To prevent bursting of sterile fluids in flexible containers
• What can happen if pressure in the air space above fluid is too high?

  It may lead to bursting of the container
• What may be required to prevent air cavitation during autoclaving?

  A fan or spray mechanism
• What is the effect of air in an autoclave?

  It can lead to superheating
• How is total pressure in an autoclave calculated?

  It is the sum of partial pressures of steam and air
• What does the equation Pro = Psteam + Pair represent?

  The total pressure in an autoclave
• What controls an unjacketed bench autoclave?

  Steam pressure