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


  • 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.


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.


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


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?