Agriculture Reference
In-Depth Information
should be carried out under good manufacturing practices
and good irradiation practices. Subsequently, standards on
various aspects of radiation processing have been devel-
oped and internationally accepted (Farrar et al., 1993).
The World Health Organization considers ionizing radi-
ation as an important process toward ensuring food safety
(Diehl, 1995). It can be a useful control measure in the
production of several types of raw or minimally pro-
cessed foods such as poultry, meat and meat products, fish,
seafood, and fruits and vegetables (Molins et al., 2001).
An increased interest in food irradiation for quality and
microbiological safety was realized by several emerging
studies on various food products, including irradiation of
fruit juices (Fan et al., 2004).
Irradiation is the process of exposing food to ioniz-
ing radiation to destroy food-poisoning bacteria such as
Salmonella, Campylobacter,
and
E. coli
and viruses, and
for insect disinfestation in foods. Youssef et al. (2002) stud-
ied effects of gamma radiation alone or with steaming on
the shelf life, microbiological quality, and physicochemi-
cal properties of mango pulps stored at 3
◦
C. Fruits were
steamed for 12 min prior to irradiation of extracted pulps
at 0-2.0 kGy. Steaming prior to irradiation at 2.0 kGy in-
creased the shelf life of unsteamed, irradiated mango pulps
from 90 to 270 days. Steaming for 12 min completely inac-
tivated the PPO activity present in mango pulps, whereas ir-
radiation at 2.0 kGy without steaming increased PPO levels.
The rate of decrease in total carotenoid and ascorbic acid
content during storage was significantly lower in steamed
than in unsteamed irradiated samples.
Sensory qualities (appearance and flavor) of early sea-
son grapefruit exposed to irradiation treatments at or below
0.4 kGy were comparable to the control after 35 days of
storage, with the exception of the 0.7 kGy treatment, which
was found to be detrimental (Patil et al., 2004). Appear-
ance rather than flavor of grapefruit was found to be more
sensitive to irradiation. Irradiation had no significant effect
on the sensory qualities of late season grapefruit. Irradiated
cantaloupe juice developed a slight irradiation off odor af-
ter treatment at 1 kGy and had strong off odor at 2 kGy and
higher (Wang et al., 2006).
A wavelength distribution such that at least 70% of the
electromagnetic energy is within the range from 170 to
2,600 nm is used. The material to be sterilized is exposed
to at least one pulse of light (typically 1-20 flashes per
second) with a duration range from 1
μ
sec to 0.1
μ
sec
(Dunn et al., 1991).
Code 21CFR179.41 issued by the FDA and the Depart-
ment of Health and Human Services approves the use of
pulsed UV light in the production, processing, and han-
dling of food. According to the FDA, pulsed light may be
safely used for the treatment of foods under the following
conditions:
The radiation sources consist of xenon flash lamps de-
signed to emit broadband radiation consisting of wave-
lengths covering the range of 200 to 1,000 nm and op-
erated so that the pulse duration is no longer than 2 ms
The treatment is used for surface micro-organism control
Foods treated with pulsed light shall receive the mini-
mum treatment reasonably required to accomplish the
intended technical effect
The total cumulative treatment shall not exceed 12.0
joules/square centimeter (J/cm
2
)
The pulsed light process developed by PurePulse Tech-
nologies Inc. (suspended operations in 2002 as a subsidiary
of Maxwell Technologies) utilizes flashes of intense broad-
spectrum pulsed light (BSPL) to sterilize pharmaceuticals,
medical devices, packaging, and water (PPT, 1999). The
spectrum closely mimics the spectrum of sunlight at sea
level with an important difference: the system delivers a
spectrum 20,000 times more intense than sunlight at the
Earth's surface during the pulse. The intense flashes of
light are less than 1 ms in duration.
Xenon Corporation (Wilmington, MA, United States)
manufactures SteriPulse decontamination and sterilization
units for batch and continuous applications. The pulsed
UV light causes formation of Pyrimidone dimers in DNA,
resulting in genetic damage to cells and their ultimate de-
struction. Types of damage induced by pulsed UV light are
(1) photolysis, (2) loss of colony-forming ability (death),
(3) inability to support phage growth (enzyme inactivation),
and (4) destruction of nucleic acid.
Pulsed light technology
Pulsed light is a method of food preservation that involves
the use of intense and short duration pulses of broad-
spectrum “white light.” The spectrum of light for pulsed
light treatment includes wavelengths in the UV to the near
infrared region. The material to be treated is exposed to
at least one pulse of light having an energy density in the
range of about 0.01 to 50 J/cm
2
at the surface (FDA, 2000).
Ultrasound
Ultrasound technology has been known for many years, its
main application areas being medical diagnostics, indus-
trial processes, and inspections. At high frequencies and
low power, it can be used as an analytical and diagnos-
tic tool, and at a very high power, it can assist process-
ing (Mizrach, 2008). Ultrasound refers to sound waves,
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