Chapter 21: Current Trends in Food Preservation: Irradiation
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What is food irradiation? What kind of preservation method? What is food exposed to?
cold food preservation method in which food is exposed to high-energy electromagnetic waves
How does food move in food irradiation?
from one end of a radiation field to another on a conveyor belt while electromagnetic waves pass through it
What does irradiation kill?
killing insects, and microorganisms
What does the FDA approve irradiation for?
– wheat and wheat flour—to reduce losses to insects and molds – white potatoes—to reduce losses from rapid sprouting in storage – spices and herbs—to lower the risk of contaminants – pork, poultry, and beef—to destroy microorganisms that cause foodborne illness
What does ionizing radiation cause? Is it a health hazard?
Ions, called free radicals - No, since the increase of free radicals is no greater than what occurs with other food preservation methods
Free radicals are unstable. What kind of changes can they create?
chemical changes that kill microorganisms and block some enzymatic reactions
What kind of foods are damaged by irradiation?
Foods with living cells, such as alfalfa sprouts and oysters
When food is irradiated, what is produced? Give examples.
• Radiolytic products - Carbon dioxide, formic acid, glucose
Is irradiation considered a food additive? Why?
• Yes - since radiolytic products are produced in the food
Are there nutritional changes due to irradiation? What is lowered? What is stable?
• Lowers vitamin B1 (thiamin) - Proteins, carbohydrates, fats, minerals, and most vitamins remain stable
When are gamma rays given off?
radioactive material that releases energy as unstable nuclei break down
What sources do gamma rays come from?
sources that must be stored in specially developed underground storage units
Name the 2 types of gamma rays used for food irradiation.
– Cobalt-60, the most common – Cesium-137, a by-product of plutonium production
What are electron beams/E-beams made of?
high-energy electrons or beta particles produced by electronic machinery
Are E-beams or gamma rays more costly?
E-beams are more costly
When is radiant energy present with electron beans?
Only present when machines are running
What is the advantage of E-beams?
No radioactive material needs to be transported or dumped
What is ultraviolet light used for? Why?
only for surface treatment because it cannot penetrate food
Do X-rays penetrate food? What can’t they do?
– penetrate food in varying degrees depending on the density – cannot be focused easily
Name the 3 units of energy.
• rad: amount of E absorbed by 1 g of material • gray: 100 rads • kilogray: 1 000 grays
What does rad mean?
radiation absorbed dose
Does irradiation increase the radioactivity in foods?
No
Who regulates facilities using radioactive sources?
The Nuclear Regulatory Commission
Name some FDA guidelines for controlling irradiation.
– All irradiated foods are tested before they are sold – Plans for production plants must be approved before building – Production plants are inspected frequently once in operation