FND300 - Thermal Processing

Blanching

Exposing fruits or vegetable to boiling water for a short period (1 to 5 minutes) of time

The Objectives of Blanching are Dependent on…

Depends on which process comes after blanching

Objectives of Blanching for Freezing and Dehydration

inactivation of enzymes

Five Objectives of Blanching for canning

inactivation of enzymes, wilting of tissues, creating anaerobic environment, creating vacuum seal, and cleaning surface of fruit/vegetables

Impact and Mechanism of Wilting of Tissues

decreases volume via loss water in central vacuole via of turgor pressure

How is an Anaerobic environment created during canning (name relevant cell part)

O2 is removed from tissues gases in plant cell vacuole

Process of Forming Vacuum Seal

when you heat something, the volume of gas expands in the headspace and when it cools down the volume decreases causing a seal

Three Steps to Verifying a Proper Vacuum Seal

lid is concave, there is no bounce when you press down and there is high pitched ring when you tap with spoon

Pasteurization

a process design to inactive microorganisms in food that are usually stored/handled under conditions that minimize further bacterial growth

Two Primary Concerns of Pasteurization Methods

time and temperature

Preservation Methods used in Combination with Pasteurization

refrigeration's, acids, and adequate packaging

Traditional Pasteurization

62C for 30 to 40 minutes

Modern High Temperature Short Time Pasteurization

72C for 15 seconds

Ultra High Temp Pasteurization

138 C to 158C for 2 to 3 seconds

What Technology Does Modern HTST Pasteurization Use

steam heated plates that milk flows over with built in cooling or plate heat exchangers

Key Feature of UHT Pasteurization

commercial sterile

Microorganisms of Concern in Pasteurization

disease causing bacteria in milk called Coxiella

Regular Sterilization

a thermal processing method that results in products where there are no viable microorganisms present

Major Concern of Non-Commercial Sterilization

the survival of bacterial spores

Five Concerns of Commercial Sterilization

pH, initial # of microorganisms in raw ingredients, storage temperature of product, heat transfer properties of food and packaging, resistance of microorganisms or spores

Why is Storage Temperature a Concern for Commercial Sterilization

Bacillus stearothermophilus becomes active at high temperatures like 35C and produces sour defect

Name Three conditions can C. botulinum grow

0.94 water activity, low acid foods, and anaerobic environments

D-Value

the time in minutes needed to reduce the microbial population by 90% (or by one log cycle) at a particular temperature

D-value is unique to three conditions

specific microorganism, specific food system and specific temp

Bot Cook

assumes the worst case scenario of 10^12 spores/mL; is a 12D process that heats 12 x D-value of Clostridum Botulinum sores at 121 C