FN3342 - Irradiation Lecture

What is ionizing radiation?

Radiant energy with some penetrating power which do not produce radioactivity in treated foods.

What is cold pasteurization?

Radiation of food does not produce significant heat in foods.

What are the 7 types of radiant energy used in electromagnetic radiation?

1. radio
2. infrared (heat)
3. visible
4. ultra violet
5. x-rays
6. alpha, beta, gamma rays
7. cosmic rays

Which type of radiant energy has the longest wave length? Which one has the shortest?

1. Radio
2. cosmic rays

In general, the shorter the wave length, the ___________ the frequency.

higher

Which type of radiant energy is typically used to inactivate microorganisms on the surface of food?

UV light

What 4 foods are allowed to be irradiated by the FDA?

1. strawberries
2. poultry
3. ground beef
4. pork

What are the 3 purposes of radiation?

1. control insects in foods and spices
2. inhibit sprouting (eg. onions, potatoes)
3. destroy vegetative cells of microorganisms

True or False?
Radiation kills spore former microorganisms.

FALSE. (would need high levels to destroy them, would also destroy the food)

What is a natural source of radioactivity?

uranium

What is a synthetic source of radioactivity?

Cobalt 60

What is a measure/unit of ionizing energy absorbed?

Radient Absorbed Dose (RAD)

What are 2 labelling requirements of foods that have been irradiated?

1. International Food Irradiation Symbol (RADURA)
2. written statement

True or False?
Not all foods can survive irradiation.

TRUE.
some foods are not resistant to sensory damage
(eg. egg whites become too runny)

True or False?
Irradiation is a good way to prevent oxidative browning.

FALSE. (enzymes are very resistant to irradiation, would be better to blanch the food)

The ________ of microorganisms to irradiation is an important factor to consider before radiating food.

resistance

True or False?
Higher doses of radiation are more expensive than lower doses.

TRUE.

What are 3 general benefits to irradiating food?

1. increase shelf life
2. reduce pathogens
3. disinfestation (remove insects)

What are 3 factors that the commercial use of irradiation is dependent on?

1. demand for the benefits that irradiation can offer
2. competitivenss with other possible processes
3. willingness of consumers to buy the irradiated product

Which 3 pathogenic microorganisms does irradiation reduce?

1. Salmonella (poultry)
2. Campylobacter
3. Trichinella Spiralis Parasites (pork)

What are 3 ways that irradiation increases the shelf life of food?

1. less spoilage of microorganisms (eg. meat, fruits)
2. inhibits sprouting (eg. potatoes, onions)
3. decreases the rate of ripening (eg. strawberries)

What is disinfestation?

Removal of insects from foods (eg. spices, grains, fruits/veg)

What levels of irradiation are safe in foods?

low-medium levels

At high doses, do irradiated foods become radioactive?

No.

Are nutrient contents of foods impacted by low-medium doses of irradiation?

No.

What are 6 disadvantages of radiation?

1. off flavour and off odour
2. destruction of B vitamins
3. Protein and other nitrogen compound degradation
4. makes ammonia, hydrogen gas, CO2, H2S
5. rancidity of fats
6. soft tissues of vegetables