Food Preservation Technology

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?

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.

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

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.

Process

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

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.

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)

Drawbacks very expensive, requires commercial equipment

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

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.

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.

Process and Uses

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

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.

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

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.

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

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

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

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

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

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

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

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.

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

Examples TetraPak - juice boxes, soups, milk

Anatomy of a TetraPak

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

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