History
1. Based on discovery of x-rays & radioactivity by Roentgen and the Curies.
2. First food application in US dates to 1946.
3. FDA approved for use on bacon in 1963. Revoked in 1968
Areas of Use
1. Food preservation
2 .Food sterilization
3. Control sprouting, ripening and insect damage
4. Control foodborne illness
Food Irradiation
Difficult to obtain approval since irradiation is considered as a food additive and not a process.
Units of Irradiation
1. Rad - a measure of ionizing radiation absorbed
2. One Gray = 100 rads
- 1 Gray equivalents to absorption of 1 joule of energy by 1 kilogram of food
3. Radicidation (< 1.0 KGy) - Low dose
4. Radurization (1 - 10 KGy) - medium dose
5. Radappertization (> 10 KGy) - high dose
Energy Available to the Food Industry for Food Irradiation
1. Selection
a. Penetrating power
b. Lack of radioactive residues in food.
c. Produce minimal heat - cold sterilization
2. Choices
a. alpha-particles
b. beta-particles
c. gamma rays
d. electrons
e. neutrons
f. x-rays
3. Sources
a. spent fuel from nuclear reactors
- CS137
- Co60
b. electron accelerators
Methods of Action
1. Direct Effects Gamma Rays & Electrons
a. Direct interaction of radiation particles with a food molecule.
b. Can not totally explain the irradiation process.
2. Indirect Effects - Gamma Rays
a. High moisture foods - water is ionized yielding highly reactive hydrogen and hydroxyl radicals
H2O H+ + OH-
b. .OH + .OH = H2O2
Effective against bacteria and enzymes
c. .H + . = H2
.H + O2 = .HO2 Peroxide radical
.HO2 + .HO2 = H2O2 + O2
DOSE DETERMINING FACTORS
1. Resistance of microorganisms
2. Resistance of enzymes
a. Generally more resistant than spores of C. botulinum
Foodborne Diseases That Could Be Prevented
- E. coli 0157:H7 & other pathogenic E. coli
- Salmonella
- Shigella
- Campylobacter jejuni
- Listeria monocyotgenes
- Cyclospora
Are consumers ready to buy irradiated foods?
1. Consumers are interested in a process that eliminates harmful microbes and reduces the risk of foodborne disease.
2. Test marketing has shown that ~ 50% will buy specific irradiated food, if given a choice between irradiated product and the same product non-irradiated.
3. If consumers are first educated about what irradiation is and why it is done, ~ 80% will buy the product in these marketing tests.