Food Preservation & Sterilization: Microbial Control & Reaction Types

What are the main types of reactions in foods?

Chemical reactions, biological reactions, and microbial growth.

What external agents are used in food preservation?

Thermal energy, chemicals, radiation, high pressure, and electric fields.

What is the purpose of commercial sterilization?

To achieve a shelf-stable food product through thermal processing.

What is the D-value in microbial survival analysis?

The time needed for a 90% reduction in the microbial population.

How does the D-value change?

It changes depending on the species and the magnitude of the external agent.

What does the thermal resistance constant (Z-value) indicate?

The increase in temperature necessary to cause a 90% reduction in the D-value.

What is the thermal death time (F-value)?

The total time required to achieve a stated reduction in a population of vegetative cells or spores.

How is the F-value calculated?

F = (number of log cycles) x D.

What is the significance of the cold spot in sterilization?

It is the location in a container where heat penetration is slowest, affecting sterilization efficacy.

What factors affect the length of time required for sterilization?

Heating conditions, heat resistance of microorganisms, enzyme activity, pH, container size and shape, and food physical state.

What is the come-up time in a retort?

The time required to reach a minimum required process temperature with uniform temperature distribution.

What does lethality (L) measure in sterilization processes?

The effectiveness of the heat treatment or sterilization process.

What is the difference between lethal rate and lethality?

Lethal rate refers to the speed of microbial death, while lethality measures the overall effectiveness of the process.

What are the two main types of commercial sterilization systems?

Batch and Continuous systems, and Aseptic processing.

What is the primary target microorganism in canning?

Clostridium botulinum, an anaerobic bacterium that forms spores.

What are the advantages of pouch-processed systems?

Reduced processing time, lower shipping costs, better sensory properties, and ease of opening.

What are the disadvantages of pouch-processed systems?

Poor physical stability compared to cans and the need for sophisticated sealing equipment.

What is the role of enzymes in food preservation?

Enzymes can affect the quality and safety of food, hence their activity must be controlled during processing.

What is the significance of microbial survival curves?

They illustrate the relationship between time and the number of surviving microorganisms during a sterilization process.