Thermal Processing of Liquid Foods

Flashcards covering key concepts from the lecture on thermal processing of liquid foods.

What is the primary objective of thermal sterilization in food processing?

To destroy all microorganisms to prevent food decomposition and the survival of pathogenic organisms.

What types of microorganisms typically affect food safety?

A mixed flora of both vegetative cells and bacterial spores.

What is the difference between vegetative cells and spores?

Vegetative cells are actively growing and cannot survive in stressful environments, while spores are dormant and can tolerate stress.

How do bacteria reproduce?

Bacteria reproduce asexually by fission.

At what rate can bacteria reproduce under favorable conditions?

Every 20-30 minutes.

What temperature and time can effectively kill vegetative bacteria?

72°C for 15 seconds.

What is the significance of Clostridium botulinum in food safety?

It is a very important food-poisoning organism that produces a deadly toxin.

What heating conditions are required to ensure the destruction of tubercle bacillus in milk?

Heating milk to 63°C for 30 minutes.

What factors influence heat treatment effectiveness in food processing?

Type of microorganism, pH of food, heating conditions, and thermal-physical properties of food.

What does the D-value represent in microbial death kinetics?

The heating time required to achieve a one decimal reduction in the microbial population.

How is the microbial death in thermal processes typically expressed?

Using common (base 10) logarithms.

What is the thermal resistance (z-value)?

The temperature change required to achieve a log-cycle change in D-values.

What is the SV (Sterilization Value) of a process?

The number of decimal reductions achieved in the microbial population at a reference temperature.

What does a 12D process imply for Clostridium botulinum spores in low acid foods?

That the process is designed to ensure safety by achieving a minimum 12 decimal reductions.

What does a typical pasteurization process aim to achieve for dairy products?

A 5 log reduction in microbial population.

What is the thermal death time (F)?

The time required to cause a stated reduction in a population of microorganisms or spores.

What is spoilage probability (SP) in food processes?

An estimate of the number of spoiled containers within a batch of processed foods.

What is the minimum D-value required for adequate inactivation of Salmonella in ground beef?

A 6.5 log reduction.

How long should apple cider be heated for effective pasteurization?

At 154.6°F for 14 seconds.

What is the temperature and time needed to achieve a typical pasteurization process for milk?

145°F for 30 minutes.

What do typical z and D values signify for pathogens in food safety?

They are critical numbers that must be identified for specific products and target organisms.

What is meant by a 4 log-cycle reduction in microbial populations?

This signifies a 99.99% reduction in microorganisms.