1. Food Preservation Technology

2. Stop and Brainstorm!
Why does food spoil? How do preservation methods work to prevent spoilage?
You have done research on traditional methods of food preservation, such as smoking, salting, and pickling. Do you recall some of the more modern, technology-based preservation practices?

3. Answers
Microorganisms, including bacteria, yeast and molds, cause spoilage. When microorganisms break down food, they produce acids and other waste products that change the colour, odour, texture, and taste of foods. Preservation either kills microorganisms, or inhibits their growth and activity.

4. Answers 2. Modern technologies include: freeze-drying irradiation
packaging types
pasteurization
chemical additives
We will focus on non-chemical methods of preservation.

5. 1. Freeze Drying Combination of freezing and drying
Food is frozen and then all water (ice crystals) are removed through sublimation.
Sublimation is the process of going directly from a solid to a gas (evaporating ice)
Same process by which clothes can dry outside in the winter time.

6. Process

7. Freeze-Drying and Microorganisms
Stop and Jot
How does freeze-drying stop microorganims from spoiling food?

8. Answer
Freeze-drying does not kill microorganisms. They survive the freezing. But all microorganisms need water to function. Since water is removed, they cannot be active or reproduce, and they die.

9. Benefits freeze-dried food can last for years, even decades
preserves nutrients, flavour, taste, colour, aroma
can be stored at room temperature
reconstituted by adding water
lightweight because all water is removed (reduces shipping costs)

10. Drawbacks
very expensive, requires commercial equipment

11. Examples Stop and Brainstorm!
What are some examples of freeze-dried foods?

12. Examples freeze dried ice cream (astronaut ice cream) instant coffee
fruit (berries, bananas, mango, cherries, etc)
vegetables (peppers, broccoli, corn, potatoes, etc)
some herbs, such as chives
some mushrooms
even some meats, like hamburger or chicken pieces found in packages of dry soup.

13. 2. Irradiation
food is exposed to a controlled amount of radiation to destroy organisms that spoil food.
in use since 1943
uses Gamma rays, a type of radiation that is very strong and deadly to living things.

14. Process and Uses

15. Benefits extended shelf-life / less spoilage
kills harmful bacteria, such as e.coli or salmonella, to prevent foodborne illness
less need for pesticides

16. Drawbacks may affect nutritional content
may create compounds in the food that are hazardous to your health
some studies show that long term exposure may have some negative health effects, but nothing has been conclusive yet.

17. However, one thing is true ...
irradiated food is NOT radioactive!

18. Government Policy
Because of the potential for health risks, the Canadian Food Inspection Agency requires food producers to indicate on their packaging if food has been irradiated. Look for this symbol so you can make an informed choice.

19. Government Policy
In some other parts of the world, a large variety of foods are irradiated, but in Canada only the following foods may be irradiated:
potatoes
onions
wheat and flour
whole or ground spices

20. U.S. Policy
In the United States, many additional foods can be irradiated:
wheat flour herbs and spices
pork all fruits and vegetables
poultry
beef

21. 3. Food Packaging
Designed to prevent moisture and microorganisms from entering food
includes bottles, cans, plastic bags, cartons, and two relatively new modern techniques:
modified atmosphere packaging
aseptic packaging

22. Modified Atmosphere Packaging (MAP)
generally used with fresh or minimally processed foods
replaces air we breathe with a specific mixture of gases that usually includes:
oxygen - to preserve appearance
carbon dioxide - suppress growth of microorganisms
nitrogen - maintains balance of other two gasses
Different foods use different gas mixtures

23. Requirements for MAP
For map to be successful, four requirements must be met:
gas mixture must suit the food being preserved
machines must be capable of mixing gases precisely
the MAP machine must create a tight seal around the food
packaging room, machines, and workers must be sterile

24. Examples pre-washed salad mixes, salad greens, baby carrots
“family packs” of fresh meat
potato chips
fresh pasta
dried foods
seafoods, like shrimp

25. Benefits maintains appearance, texture, and nutrition
creates an environment that suppresses growth of microorganisms

26. Drawbacks
expensive
gases create bulky packages that increase shipping costs
CO2 content is regulated, as too much of it can mask regular signs of spoilage, especially in meat.

27. Aseptic Packaging Aseptic - free from contamination by microorganisms
used to package aseptic processed foods - foods that have been sterilized by heat to kill microorganisms (pasteurization)
prevents microorganisms from getting into food

28. Examples
TetraPak - juice boxes, soups, milk

29. Anatomy of a TetraPak

30. Benefits
liquids can be stored at room temperature, no refrigeration required until opened - not true for all foods (regular dairy)
maintains nutritional content and flavour of food
packaging is lightweight - better for shipping

31. Drawbacks
difficult to recycle due to the variety of materials used in the packaging.