Course:FNH200/Lessons/Lesson 06/Page 06.9

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6.9 Summary of Lesson 6

  • Thermal Processing (TP) and packaging materials used in TP are designed to kill microorganisms and extend the food's shelf life.
  • Blanching mainly inactivates undesirable enzymes in food. It is usually used in combination with other preservation (processing) methods.
  • The magnitude of the thermal process will have a different impact on the food's preservation. E.g. Pasteurization destroys pathogens and only some of the spoilage-causing microorganisms, whereas commercial sterilization destroys both pathogens and spoilage-causing microorganisms.
  • Heat treatments are determined using "thermal death curves" (TDRC, TDTC). These curves provide important information of the survival and heat-resistance of different microorganisms, the effect of different temperatures, etc.
  • UHT with aseptic packaging allows food to be stored at room temperature.
  • A wide margin of safety is desired in order to ensure that Clostridium botulinum is destroyed.
  • Conduction and convection are mechanisms of heat transfer.
  • Some food constituents can have a "protective" effect on food that is being thermally processed
  • Different packaging materials have a specific use for the different types of thermal processing methods.

Supplemental Video: Tetra Pak® A6 - Meet the filling machine for Tetra Evero® Aseptic

Reference

  • Potter, N. N. and J.H. Hotchkiss. 1995 or 1998. Heat Preservation and Processing in Food Science, 5th ed. Chapman and Hall, New York, NY. Chapter 8.

Authorship:

FNH 200 Course content on this wiki page and associated lesson pages was originally authored by Drs. Brent Skura, Andrea Liceaga, and Eunice Li-Chan. Ongoing edits and updates are contributed by past and current instructors including Drs. Andrea Liceaga, Azita Madadi-Noei, Nooshin Alizadeh-Pasdar, and Judy Chan.

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1. What is the main purpose to pasteurize milk?

To eliminate pathogenic microorganisms
To inactivate polyphenol oxidase
To eliminate spoilage-causing microorganisms
To eliminate psychrotrophic spoilage-causing microorganisms


2. Type text here or a no-break space code

What is the most common way to sterilize Tetra Pak?


3. If the amount of microorganisms increases in a food the D-value does NOT change, but the margin of safety decreases.

TRUE.
FALSE.


4. Spores are more heat resistant than vegetative cells. The means that spores have higher D-value than vegetative cells.

TRUE.
FALSE.


5. If the D-value of a species of bacteria is 2 minutes at 70˚C and there are 10,000 of these bacteria in a given food, then how many bacterial cells would be left in that food if it was heated at 70˚C for 6 minutes?

10
1000
100
50