Irradiation - Food Shelf Life Stability: Chemical, Biochemical, and Microbiological Changes - page 112

processing. Sensitivity of Clostridium sporogenes spores were similar in both pro-
cessing methods. Next the authors studied the consumer acceptability and preference
for these combination processes. 268 The two most promising heat irradiation treat-
ments were (1) F 0 value of 2 at 2.5 kGy and (2) F 0 value of 1 at 4.5 kGy. Ranked
preference testing was performed to determine consumer preference. Treatment
(1) performed better for appearance and color when compared to canned products,
but treatment (2) was significantly favored over treatment (1) in all characteristics
except texture. Earlier work by this group established the principle of using heat
irradiation combination processing for producing high quality shelf-stable low acid
food products. 269 Mushrooms in brine treated by heating 1 min at 120°C, followed
by irradiation at 4.5 kGy or heating 2 min and irradiated at 2.5 kGy, were signifi-
cantly different in all sensory properties than for either heat processing or irradiation
treatment alone. Earlier work by Beaulieu et al. 270 and Lescano 271 showed that
irradiation at doses of 2 to 3 kGy was effective for extending the shelf life of
mushrooms. Irradiated fresh mushrooms had about a threefold extension of shelf
life compared to the controls, with less browning and a delay in cap opening.
Barkai 272 reported on the use of heat-irradiation treatments to control fungal
development in red tomatoes. Under natural infection conditions, hot water dip
followed by irradiation at 0.5 kGy synergistically reduced fungal decay from 90 to
100%. El-Assi 273 studied the radiation induced textural changes in tomatoes, finding
that green tomatoes were affected more than pink fruit and that the effects were
dose dependent. Fruits irradiated green softened during storage and polygalactur-
onase activity decreased to about 10% of that of the controls. In the irradiated pink
fruit PG activity decreased less but softening still occurred.
CONCLUSIONS
Irradiation processing has been extensively researched and is now being used for
many food commodities. It has been successfully used to reduce pathogenic bacteria,
eliminate parasites, decrease postharvest sprouting, and extend shelf life of fresh
perishable food. Acceptance of the idea of irradiated food products in North America
has been slower than in some other countries. The main problems for industry are
no clear definition of the need for irradiation, large capital investment required ($3 to
4 million plant), transportation logistics, and consumer concerns. Contrary to con-
sumer misinformation, all irradiated fruits and vegetables studied thus far are safe
for human consumption and suffer no reduction in nutritional quality for doses under
2.0 kGy. 274
For fruits and vegetables, cost and quality problems preclude the use of irradi-
ation for extension of shelf life except for the few cases noted. Limiting factors in
widespread adoption of the process are (1) cost as fruit and vegetables are low value
crops; (2) much of the produce is grown on small acreages distributed over wide
areas; (3) the produce is shipped to small local packing houses for shipment to large
distribution centers (no single large facility handles all produce from the region);
(4) the consumer is unwilling to pay the increased cost of irradiated products;
(5) many other cheaper chemical methods are available. The most likely use of
irradiation for these products is for insect control.