Novel Processing Technologies for Fruits - Tropical and Subtropical Fruits: Postharvest Physiology, Processing and Packaging - page 85

well as the general provisions for food irradiation. Sub-
part B also lists other radiation processes, including ra-
diofrequency radiation, ultraviolet, and pulsed light. These
radiation processes are covered elsewhere and will not be
included in this chapter. Subpart C describes packaging
materials for irradiated foods.

ples were also associated with flavor improvement which
resulted in better sensory preference.
Alothman et al. (2009) studied the effect of ultraviolet
(UV-C) treatment on total phenol, flavonoid, and vitamin C
content of fresh-cut fruits (pineapple, banana, and guava).
Total phenol and flavonoid contents of guava and banana in-
creased significantly with the increase in treatment time. In
pineapple, the increase in total phenol content was insignif-
icant, but the flavonoid content increased significantly after
10 min of treatment. UV-C treatment decreased the vitamin
C content of all three fruits.
The UV-C wavelength of 254 nm is used for the disinfec-
tion and has a germicidal effect against micro-organisms.
A novel turbulent flow system was reported for the treat-
ment of apple juice, guava-pineapple juice, mango nectar,
strawberry nectar, and two different orange and tropical
juices (Keyser et al., 2008). The UV-treated juices retained
taste and color profiles. Ultraviolet dosage levels (J/liter)
of 230, 459, 689, 918, 1,148, 1,377, 1,607, and 2,066 were
applied to different juice products in order to reduce the
microbial load to acceptable levels. The UV-C radiation
was successful in reducing the microbial load in different
single strength fruit juices and nectars.

Ultraviolet (UV) light
UV light technology is a nonchemical, nonthermal, sim-
ple, and inexpensive approach to disinfection that requires
very low maintenance. UV light is defined as the elec-
tromagnetic radiation in the spectral region classified into
four wavelength ranges: UV-A (315-400 nm), UV-B (280-
315 nm), UV-C (200-280 nm), and Vacuum-UV (100 nm-
200 nm) (Krishnamurthy et al., 2008). UV-C light treat-
ment, which exploits the radiation from the electromagnetic
spectrum from 200 to 280 nm, is a powerful surface germi-
cidal method, easy to use, and characterized by favorable
costs of equipments, energy, and maintenance (Barbosa-
Canovas et al., 1998; Miller et al., 1999). It is safe to apply,
but some simple precautions are necessary to avoid worker
exposure to light and evacuate the generated ozone.
There is a particular interest in using UV light to treat fruit
juices, specially apple juice and cider. Other applications
include disinfection of water supplies and food contact sur-
faces. The germicidal properties of UV irradiation are due
to DNA mutations induced by DNA absorption of the UV
light. This mechanism of inactivation results in a sigmoidal
curve of microbial population reduction.
To achieve microbial inactivation, the UV radiant expo-
sure must be at least 400 J/m 2 in all parts of the product.
Critical factors include the transmissivity of the product;
the geometric configuration of the reactor; the power, wave-
length, and physical arrangement of the UV source(s); the
product flow profile; and the radiation path length. UV
may be used in combination with other alternative pro-
cess technologies, including various powerful oxidizing
agents such as ozone and hydrogen peroxide, among others
(FDA, 2000).
The effectiveness of UV-C light exposure on safety and
quality of fresh-cut fruit was investigated with reference to
melon cubes by Manzocco et al. (2011). UV-C light was ap-
plied during cutting operations and before packaging. Fruit
exposure to UV-C light led to 2 log reductions for both to-
tal viable count and Enterobacteriaceae, whose counts re-
mained 2 log units lower than that of the untreated sample
during storage. No significant effect of UV-C light treat-
ment on product color and firmness was detected during
storage at 6 ◦ C for up to 14 days. The UV-C treated sam-

Ionizing radiation
Ionizing radiation for the treatment of packaged food can
be achieved using gamma rays (with Co-60 or Cesium-137
radioisotope), electron beams, or X-rays, as specified in
21 CFR 179.26(a). The effects of radiation on matter gen-
erally depend on the type of the radiation and energy level
as well as the composition, physical state, temperature and
environment of the absorbing material, and whether it is
food or the packaging materials in contact with the food.
Chemical changes in matter can occur via primary radiol-
ysis effects, which occur as a result of the adsorption of
the energy by the absorbing matter, and can have biological
consequences in the case where the target materials include
living organisms. With proper application, irradiation can
be an effective means of eliminating and/or reducing the
microbial load and thus the food-borne diseases they in-
duce, thereby improving the safety of many foods as well
as extending their shelf life (Komolprasert, 2007).
Expert groups of national and international organiza-
tions as well as many regulatory agencies have generally
concluded that irradiated food is safe and wholesome and
that food irradiation at commonly used dosing levels does
not present any enhanced toxicological, microbiological, or
nutritional hazards to the food beyond those brought about
by conventional food processing techniques. These experts
have agreed that irradiation of food for microbial safety