Feasting
in space
Dr
Arun Sharma explains the significance of radiation technology, which
is increasingly being used to produce food for astronauts on a space
mission
India
is making extensive plans to send a manned flight to the moon in the
foreseeable future. But are we equipped to provide our astronauts with
a wholesome and safe meal during their journey in space? The answer
is both, yes and no. We have the technology to develop food products
that would withstand the vagaries of space, but no meal or food product
has yet been developed specifically to cater to the needs of space explorations.
When it comes to providing meals with assured safety and quality to
the astronauts, the only technology that can be relied upon is the radiation
technology. That is why National Aeronautics and Space Administration
(NASA) has a separate radiation facility attached to its kitchen that
caters to the food needs of the crew of US space flights.
The scientists from NASA realised the potential of using radiation technology
for making ambient-stable foods for space flights at the NASA Food Technology
Commercial Food Centre. Gradually, the details of the technology trickled
out and a few countries that had irradiation facilities including South
Africa, France, China and India started implementing the technology.
Radiation technology is different from the one used in the preservation
and conservation of food at lower doses (0.03-10 kGy) that could be
applied at ambient temperatures to achieve different technological purposes
summarised in Table 1. In this case it involves use of doses between
10-45 kGy of radiation at very low temperatures of about -20 to -40
°C.
The technology
The processing of food through radiation involves
a controlled application of energy from ionising radiations such as
gamma rays, electrons and x-rays. Gamma rays and x-rays are short wavelength
radiations of the electromagnetic spectrum. Gamma rays are emitted by
radioisotopes such as cobalt-60 and cesium-137, while electrons and
x-rays are generated by machines using electricity. Irradiation works
by disrupting the biological processes that lead to the decay of food
items. In its interaction with water and other molecules that make up
food and living organisms, the radiation energy is absorbed by the molecules
it contacts. The interaction of radiation and radiolytic products of
water with DNA impairs the reproducing capacity of micro-organisms and
insects as well as the ability of potato and onion to sprout.
Radiation processing plant
The processing of food by radiation is held inside
an irradiation chamber shielded by 1.5 - 1.8 m thick concrete walls.
Food, either prepacked or in bulk, is placed in suitable containers
and is sent into the irradiation chamber with the help of an automatic
conveyor. The conveyor goes through a concrete wall labyrinth, which
prevents radiation from reaching the work area and the operator room.
When the facility is not in use the radiation source is stored under
water at a depth of 6 m. The water shield does not allow radiation to
escape into the irradiation chamber, thus permitting free access to
personnel carrying out plant maintenance activities. For treating food,
the source is brought to the irradiation position above the water level
after activating all safety devices.
The food is placed in carriers or tote boxes, which are mechanically
sent inside and positioned around the source rack and are
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