Enclosure 
IRRADIATION PRESERVATION AND PRELIMINARY COST ESTIMATES 
"Research in the use of atomic energy for food preservation began on a large scale 
in 1953. Because of the many complex problems associated with radiation sterilization, 
researchers have found that the use of low doses for pasteurization is the most practical 
method. There are several factors responsible for effective radiation preservation; first, 
radiation dose; second, selection of variety and maturity of product; third, preirradia- 
tion treatment; and fourth, packaging. The radiation dose required depends on the num- 
ber and kind of microbial organisms present on the product before irradiation. Without 
loss of quality, most fruits and vegetables can be irradiated at a medium level... to 
extend the shelf life from two to six weeks at refrigeration temperatures. ''7 
Atomic irradiation retards and destroys micro-organisms in food which are respon- 
sible for spoilage; thereby allowing an extension of the storage life. Radiation dosages of 
a number of times the intensity needed for pasteurization are required before any danger 
to human health is possible from radiation in food. Wholesomeness tests have shown that 
radiation pasteurized fruits and vegetables are acceptable for human consumption ina 
similar manner as their fresh forms when quality, taste, color, etc., are considered. 
In addition, research has shown that this new process can be used effectively to control 
ripening of fresh produce. 
"The cost of radiation sources differs with such variables as the type of source, the 
size of plant, and the load factor at the plant. Based upon existing knowledge, an esti- 
mate has been made that ina 10-ton-per-hour facility with annual volume of 40,000 tons 
per year, a gamma source could process fruit at a cost of approximately five mills per 
pound, This might add 25 percent or more to the costs of a typical orange packing opera- 
tion, and for other commodities the increase might be even greater. Whether this cost 
is at a level at which packers will be encouraged to use radiation pasteurization depends 
on the potential economic advantages the user may realize from the process, '' 
Based on cobalt 60 at a cost of 50 cents per curie, the initial cost of penetrating 
source material for a facility of the size indicated above would be about $720, 000; and in 
addition, the plant investment would be about $380,000. Today, the price of cobalt 60 is 
about $1.00 per curie.? It should be noted that the research and development time neces- 
sary to produce a commercial size facility has been estimated to be about four years. 
The table below contains preliminary cost estimates. 
A surface treatment facility large enough to handle 40, 000 tons per year witha 10- 
ton-per-hour capacity would be expected to cost about 1/10 as much as for a penetrating 
source. The cost per unit for processing then would be about 1/5 as much as for a pene- 
trating source such as cobalt 60. Accelerated electrons and strontium 90 are examples 
of surface treatment sources. It should be emphasized that surface source technology is 
not thoroughly developed yet, and to develop it for commercial application implies a long- 
term research and development effort. 
* Pierson, N.W., Wilcox, E.B. and Salunkhe, D.K. Radiation Preservation of Fruits, Utah Farm and Home Science, 
Vol. 23, No. 1, Agricultural Experiment Station, Utah State University, Logan, March 1962, Quarterly. 
2 Stanford Research Institute. Radiation Preservation of Selected Fruits and Vegetables. SRIA-30, Jan. 1961, p. 17. 
F SRIA-30, p. 54, A curie is a unit of mass of radium emanation, being the amount in equilibrium with one gram of 
radium, 
23 
