Int.J.Curr.Microbiol.App.Sci (2014) 3(4): 549-555   
                ISSN: 2319-7706 Volume 3 Number 4 (2014) pp. 549-555 
                http://www.ijcmas.com
                 Review Article  
                                      Food Irradiation - Technology and Application   
                                                      B.Kalyani* and K.Manjula  
                             Department of Home Science, S.V.University, Tirupati, A.P., India-517502 
                                                           *Corresponding author    
                                           A B S T R A C T                            
                                      The technology of food irradiation is gaining more and more attention around the 
                                      world. In comparison with heat or chemical treatment, irradiation is more effective 
                                      and appropriate technology to destroy food borne pathogens. Radiation technique 
                   Keywords           makes the food safer to eat by destroying bacteria which is very much similar to the 
                                      process of pasteurization. Radiation does not leave the food items radioactive for 
                   Radiation,         two seasons. First, the gamma rays from cobalt-60 used in food radiation are not 
                   technology,        energetic  enough to make it radioactive. Second, as the food never comes into 
                   food,              contact  with  the  source  directly,  it  is  not  possible  for  the  food  to  become 
                   packaging.         contaminated with radioactive material. In the changing scenario of world trade, 
                                      switching over to radiation processing of food assumes great importance. Radiation 
                                      will be moving fast to the status of a 'wonder technology' to satisfy the sanitary and 
                                      phyto sanitary requirements of the importing countries. Food once irradiated, can 
                                      be prone to re-contamination unless appropriately packed Therefore, if radiation 
                                      treatment  is  intended  to  control  microbiological  spoilage  or  insect  infestation, 
                                      prepackaging becomes an integral part of the process.
                 Introduction  
                 India has been practicing various methods              unmanageable  distances  between  the 
                 of    food     preservation      from     time         production  and  consumption  centers  and 
                 immemorial such as sun drying, pickling                the rising gap between demand and supply 
                 and  fermentation.  These  methods  were               have     posed      great    challenges      to 
                 supplemented        with     more      energy          conventional       techniques      of     food 
                 consuming  techniques  like  refrigeration,            preservation and thereby to food security.  
                 freezing  and  canning;  however  had  its             The hot and humid climate of the country 
                 merits and demerits. The quest was ever                is  quite  favorable  to  the  growth  of 
                 on for newer methods of food preservation              numerous  insects  and  micro  organisms 
                 with  least  change  in  sensory  qualities.           which  destroy  stored  crops  and  cause 
                 Preservation  of  food  items  is  a  pre-             spoilage of food. In the changing scenario 
                 requisite  for  food  security.  The  seasonal         of world trade, switching over to radiation 
                 nature of production and the long and                  processing     of    food    assumes      great 
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                                             Int.J.Curr.Microbiol.App.Sci (2014) 3(4): 549-555   
                   importance.  Radiation  processing  can  be         facilities  for  radiation  processing  of food 
                   used  for  disinfestations  of  pests  and          in public as well as private sectors.  
                   disease-causing organisms from a range of 
                   products including fruits and vegetables.           The Ministry extends assistance for setting 
                                                                       up facilities for food processing by using 
                   Radiation as a Preservation Technique               radiation    technology      to    promote 
                                                                       commercial  use  of  this  technology  in 
                   Radiation is one of the latest methods in           India. BARC will be the nodal agency for 
                   food  preservation.  Radiation  technique           assistance  and  guidance  on  process 
                   makes the food safer to eat by destroying           technology    while    BARC/BRIT  will 
                   bacteria which is very much similar to the          provide  information  on  availability,  cost 
                   process  of  pasteurization.  In  effect,           and  possible  alternatives  of  essential 
                   radiation disrupts the biological processes         machinery including pollution control and 
                   that lead to decay and the ability to sprout.       disposal  of  radio  isotopes.  BARC  can 
                   Being  a  cold  process,  radiation  can  be        provide  training  to  the  staff  on  various 
                   used  to  pasteurize  and  sterilize  foods         aspects  of  operation  and  safety  in  India 
                   without causing changes in freshness and            (saylor, and, Jordan, 2000).  
                   texture of food unlike heat. Further, unlike 
                   chemical  fumigants,  radiation  does  not          Radiation Processing  
                   leave any harmful toxic residues in food 
                   and is more effective and can be used to            Food irradiation is a technology that can 
                   treat packaged commodities too.                     be safely used to reduce food losses due to 
                   Countries  including  India  guard  against         deterioration and to control contamination 
                   import of exotic insect pests by requiring a        causing illness and death. Food irradiation 
                   post  harvest  disinfestations  treatment  of       uses  radiant  energy     electron  beams, 
                   commodities  that  can  carry  pests.  India        gamma  rays  or  x-rays  to  rid  food  of 
                   will  not  be  able  to  resist  the  flow  of      harmful  microorganisms,  insects,  fungi 
                   radiated  foods  to  the  country  as  a            and other pests, and to retard spoilage. It 
                   prohibitive  policy  would  be  difficult  to       does    not   make     food    radioactive. 
                   justify on technical grounds and could be           Irradiation kills pathogens and makes them 
                   challenged under the WTO agreement as a             incapable of reproduction.  
                   technical  barrier  to  trade.  Above  all,         There  are  several  processes  that  are 
                   radiation technology for food preservation          collectively   referred   to    as    Food 
                   will  be  moving  fast  to  the  status  of  a      Irradiation . The object of each process is 
                   'wonder technology' to satisfy the sanitary         to kill or impair the breeding capacity of 
                   and  phyto  sanitary  requirements  of              unwanted living organisms or to affect the 
                   importing countries.                                product  morphology  in  a  beneficial  way 
                   The     Ministry   of    Food    Processing         that  will  extend  shelf-life.  Each  process 
                   Industries  has  a  major  role  to  play  in       has  an  optimal  dose  of  ionizing  energy 
                   ensuring food security by processing and            (radiation) dependent on the desired effect. 
                   preserving  food  items  to  be  released  in       The dose of radiation is measured in grays 
                   consuming areas and at lean periods. The            (Gy).  A    gray    is  a  unit  of  energy 
                   ministry  has  a  number  of  schemes  to           equivalent  to  1  joule  per  kilogram.  This 
                   encourage  entrepreneurs  for  setting  up          unit  of  measure  is  based  on  the  metric 
                                                                       system. Thus, 1 kilogray (kGy) is equal to 
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                 1,000  grays  (Gy).  All  three  forms  of            radiation  energy  is  converted  to  heat 
                 ionizing energy have the same effect, gray            during  treatment,  the  process  typically 
                 for gray. Some of the major processes are:            increases the product temperature by about 
                                                                       1 degree Celsius(Benebion.).  
                 Pasteurization (Pathogen Reduction)   
                                                                       Types of Radiation sources  
                 Irradiation is used to effectively eliminate 
                 disease   causing     organisms     including         Three principal types of radiation source 
                 bacteria  and  parasites.  (e.g.  Irradiating         can be used in food irradiation according 
                 ground beef to make it safe from E. coli              to the  
                 O157:H7. Irradiating live oysters to make 
                 them safe from vibrio.)                               Codex Alimentarius General Standard 
                                                                       (Food and agriculture organization, world 
                 Sterilization   Irradiation is used at a very         health organization, 1984) :  
                 high  dose  to  eliminate  all  organisms  so 
                 that  refrigeration  is  not  required  (shelf                (a)    Gamma        radiation    from 
                 stable).  (e.g.  Certain  foods  are  sterilized      radionuclides such as 60Co or 137Cs 8; 
                 for NASA astronauts.)                                         (b)  Machine  sources  of  electron 
                 Sanitation    Irradiation is widely used to           beams with energies up to 10 MeV; 
                 reduce  organisms  for  spices,  herbs  and                   (c)     Machine        sources      of 
                 other  dried  vegetable  substances.  (e.g.           bremsstrahlung  (X  rays)  with  electron 
                 Irradiating spice blends that are added to            energies up to 5 MeV.  
                 meat  for  hot  dogs  and  other  Ready  to 
                 Eat   products  that  may  not  be  cooked            Because  of  their  greater  penetrating 
                 again.) the population of spoilage causing            capability,   rays and X rays may be used 
                 organisms,  including  bacteria  and  mold.           for processing of relatively thick or dense 
                 On  certain  fruits  and  tubers,  irradiation        products.  For  situations  where  only  a 
                 delays  ripening  and/or  sprouting.  (e.g.           shallow penetration is needed and where 
                 Irradiating   berries   to    reduce    mold.         rapid conveyor speeds can be used, high 
                 Irradiating  fresh  fruits  to  extend  their         power  electron  beams  may  provide  a 
                 market reach. Irradiating potatoes, onions            higher  output  at  lower  cost  per  unit  of 
                 and  garlic  to  impair  cell  division  and          product when large amounts of product are 
                 hence allow them to go through the  off               involved.  
                 season without sprouting.)  
                                                                       Gamma rays  
                 Disinfestation    Irradiation is used to stop 
                 reproduction     of    both    storage    and         The     rays  used  in  food  processing  are 
                 quarantine  insect  pests.(e.g.  Irradiating          obtained  from  large  60Co  radionuclide 
                 foreign produced mangoes to eliminate the             sources.    This   type    of   radiation    is 
                 seed weevil, which is a quarantined pest,             essentially  monoenergetic  (60Co  emits 
                 for import to the US. Irradiating papaya is           simultaneously       two      photons      per 
                 to   eliminate    fruit  flies,  which  are           disintegration  with  energies  of  1.17  and 
                 quarantined pests, for import from Hawaii             1.33  MeV).  Using  analytical  techniques 
                 or foreign countries into the US mainland.)           such as the point kernel or Monte Carlo 
                 All three forms of irradiation are referred           methods, it is possible to compute the dose 
                 to as a  cold process . Although all of the           distribution  in  irradiated  food  products 
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                      even  when  very  complicated  source                      importance that the dosimetry techniques 
                      geometries  such  as  extended  plaque                     used for dose determination are carried out 
                      sources are used. The resulting depth dose                 accurately     and  that  the  process  is 
                      distribution  in  the  food  products  usually             monitored.  
                      resembles  an  approximately  exponential 
                      curve.  Irradiation  from  two  sides  (two                Food packed in crates or boxes is placed 
                      sided  irradiation),  obtained  either  by                 on  conveyor  belts  and  moved  into  the 
                      turning the process load or by irradiation                 heart of the irradiator, where it is exposed 
                      from two sides of a plaque source, is often                to  the  radiation  source.  Electron  beam 
                      used to increase the dose uniformity in the                irradiators  can  cleanse  packaged  food  at 
                      process  load  (Olivieira,  et  al.,  2000;                the  end  of  food-processing  production 
                      saylor, m.c., jordan, 2000).                               lines. High-energy waves pass through the 
                                                                                 food,  exciting  the  electrons  in  both  the 
                      Electrons                                                  food and any pests or pathogens. When the 
                                                                                 electrons  absorb  enough  energy,  they 
                      Electrons  emitted  by  accelerators  have                 break  away  from  their  atoms,  leaving 
                      fairly    narrow  spectral  energy  limits                 positively      charged      centers     behind. 
                      (usually  less  than  ±10%  of  the  nominal               Irradiation      disrupts     the     molecular 
                      energy).  The  energy  of  the  electrons                  structure;  kills  or  reduces  the  number  of 
                      reaching the product is further controlled                 bacteria  and yeasts; delays the formation 
                      by  the  bending  magnets  of  the  beam                   of  mold;  and  sterilizes  or  kills  parasites, 
                      handling system, if applicable. The range                  insects,  eggs  and  larvae.  Levels  of 
                      of an electron in a medium is finite (unlike               absorbed radiation are currently measured 
                      that for photons) and is closely related to                in kilo grays (kGy).  
                      its energy (Hayashi, 1998).   
                                                                                 Food Irradiation Applications  
                      Bremsstrahlung (X rays)  
                                                                                 The scientific community has defined 
                      Bremsstrahlung           irradiator        design          three levels of food irradiation:  
                      principles are essentially the same as those 
                      for  electron  irradiators  .An  extended                  Applications at low dose levels (10 Gy 1 
                      source  of  X  rays  is  achieved  by                      kGy)  
                      distributing  the  primary  electron  beam 
                      over  a  target  (X  ray  converter)  of                   Sprouting  of  potatoes,  onions,  garlic, 
                      sufficient     size.   In    contrast    to    the         shallots,  yams,  etc.  can  be  inhibited  by 
                      radionuclide  sources,  which  emit  nearly                irradiation in the dose range 20 150 Gy. 
                      monoenergetic  photons,  bremsstrahlung                    Radiation affects the biological properties 
                      (X ray) sources emit photons with a broad                  of  such  products  in  such  a  way  that 
                      energy  spectrum  (Aikawa,  Y,  2000;                      sprouting  is  appreciably  inhibited  or 
                      Cleland, M.R., Pageau, G.M., 1987).                        completely        prevented.      Physiological 
                                                                                 processes such as ripening of fruits can be 
                      The effectiveness of processing of food by                 delayed  in  the  dose  range  0.1 1  kGy. 
                      ionizing  radiation  depends  on  proper                   These  processes  are  a  consequence  of 
                      delivery of absorbed dose and its reliable                 enzymatic  changes  in  the  plant  tissues. 
                      measurement.  For  food  destined  for                     Insect  disinfestations  by  radiation  in  the 
                      international  trade,  it  is  of  the  utmost             dose  range  0.2 1  kGy  is  aimed  at 
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