Chapter 5 food irradiation - blackboard | Môn Food technology - Trường Đại học Quốc tế, Đại học Quốc gia Thành phố Hồ Chí Minh

lOMoAR cPSD| 58562220 Le Ngoc Lieu Office: A1.706 Email: lnlieu@hcmiu.edu.vn lOMoAR cPSD| 58562220
The emission and propagation of energy through matter or space by electromagnetic disturbances called photons.
The process of applying radiation to matter
Application of irradiation as ionizing energy to foods 2 lOMoAR cPSD| 58562220
Physical treatment that consists of exposing foods either prepackaged or in bulk to
the direct action of electronic, electromagnetic rays
When made to bombard against materials, they can knock off an electron from an
atom or molecule causing ionization. For this reason, these are often called ionizing irradiation.
The X- and gamma-rays are very short wavelength radiations that have very high associated energy levels. lOMoAR cPSD| 58562220
Prevention of foodborne illness
Effectively eliminates microbes, e.g. Salmonella and E. Coli Preservation 4 lOMoAR cPSD| 58562220
Destroy/ inactivate organisms that cause spoilage and decomposition. Control of insects
Destroys insects e.g. imported fruits.
Delay of sprouting and ripening
Lengthen the longevity of products e.g. potatoes. Sterilization
Useful for patients in the hospital especially with impaired immunity Sprout inhibition Quarantine lOMoAR cPSD| 58562220 Fruits Onion, potato, garlic, ginger Insect disinfestation Shelf-life extension Pathogen reduction Cereals, dry fruits Chicken, meat, fish Spices, flesh foods 6 lOMoAR cPSD| 58562220 lOMoAR cPSD| 58562220 8 lOMoAR cPSD| 58562220
Gamma Rays are emitted from radioactive forms of the element cobalt (Co60)
(1.17 and 1.33 MeV) or of the element cesium (Cs137) (0.662 MeV). Gamma
radiation is used routinely to sterilize medical, dental and household products
and is also used for the treatment of cancer.
X-rays (5 Mev) are produced by reflecting a high energy stream of electrons off a
target substance (usually one of the heavy metals) into food. X-rays are also
widely used in medicine and industry to produce images of internal structures.
Electron beam (or e-beam) (10 MeV) is similar to x-rays and is a stream of
highenergy electrons propelled from an electron accelerator into food.
The international unit of measurement is the Gray (Gy).
One Gray represents one joule of energy absorbed per kilogram of irradiated
product. One Gy is equivalent to 100 rad (radiation absorbed dose)
The desired dose is achieved by the time of exposure and by the location of the
product relative to the source. lOMoAR cPSD| 58562220
Depend upon the mass, bulk density and thickness of the food
Radioactivity is the ability of a substance to emit high energy particles. When particles
hit the target materials they may free other highly energetic particles
“Low” doses <1 kGy (Radicidation)
Controls insects in grains and fruits 10 lOMoAR cPSD| 58562220 Inhibit sprouting in tubers
Delay the ripening of some fruits/vegetables
Reduce the problems of parasites in products of animal origin. (e.g: Trichinella spiralis in pork)
“Medium” dose (1-10 kGy) (Radurization)
Control Salmonella, Shigella, Campylobacter, Yersinia, Listeria and E.coli in meat poultry and fish.
Delay mold growth on strawberries and other fruits
“High” dose (> 10kGy) (Radapperization)
Kill microorganisms and insects in spices
Commercially sterilize foods, destroying all microorganisms of public health
concern (i.e, special diets for people with weakened immune systems) lOMoAR cPSD| 58562220 12 lOMoAR cPSD| 58562220 lOMoAR cPSD| 58562220 Energy aspect 14 lOMoAR cPSD| 58562220
“Cold pasteurization” The maximum dose of 10 kGy recommended by the Codex General Standard for Irradiated Foods is equivalent to the heat energy required to increase the temperature of water by 2.4oC. Irradiation is often referred to as a ‘’cold
pasteurization’’ process as it can accomplish the same objective as thermal pasteurization of liquid foods, For example milk, without any substantial increase in product temperature. ! lOMoAR cPSD| 58562220
To make the food become radioactive, it will require a lot of energy; 15MeV.
Foods are actually naturally radioactive, due to natural presence of Ca, P, K, and S elements in the food.
The longer the storage time of irradiated food, more natural radioisotopes have time to undergo decay. " 16 lOMoAR cPSD| 58562220 ! lOMoAR cPSD| 58562220 18 lOMoAR cPSD| 58562220 Comparison of radiation sensitivity of different organisms " lOMoAR cPSD| 58562220 " 20