IAEA-TECDOC-843 Shelf-stable foods through irradiation processing Report prepared Foodthe by Preservation Section, Joint FAO/IAEA Division Nuclearof Techniques Food in Agriculture and INTERNATIONAL ATOMIC ENERGY AGENCY The IAEA doe t normallsno y maintain stock f reportso thin si s series. However, microfiche copies of these reports can be obtained from INIS Clearinghouse International Atomic Energy Agency Wagramerstrasse5 P.O. Box 100 A-1400 Vienna, Austria Orders should be accompanied by prepayment of Austrian Schillings 100, in the form of a cheque or in the form of IAEA microfiche service coupons which may be ordered separately from the INIS Clearinghouse. originatine Th g Sectio f thino s publicatio IAEe th An i was: Food Preservation Section Joint FAO/IAEA Division International Atomic Energy Agency Wagramerstrasse 5 P.O. Box 100 A-1400 Vienna, Austria SHELF-STABLE FOODS THROUGH IRRADIATION PROCESSING IAEA, VIENNA, 1995 IAEA-TECDOC-843 ISSN 1011-4289 © IAEA, 1995 Printe IAEe th AustriAn y i d b a November 1995 FOREWORD Irradiation in combination with other food processes/treatments, at sterilizing or at substerilizing doses s lonha ,g been know e capablb o n t f yieldino e g shelf-stable foods, particularly dry-packed meat, poultry and fish/shellfish products having very good eating quality and nutritional value. However, other than highly specific, targeted uses with astronauts and cosmonauts in space, with immune-suppressed medical patients at one US hospital, and for military feeding plus supplying small niche 'markets' in the Republic of South Africa, ther bees ecommerciaha o nn l exploitatio researce th f ndevelopmeno d han t that has gone into establishing this potentially very usefu valuabld an l e food irradiation application category t whaBu . t with rising global energy costs immune-compromised/suppressed an , d population e increaseth n o s , together with increasing consumer deman r minimallfo d y processed superior eating quality food developen i s d countries especially potentiae th , d an l nee r industriadfo f thio se largelus l y neglected food irradiation are becomins ai g mord ean more apparent. A Consultants Meeting on Irradiation for Shelf-Stable Foods was held in Vienna from 11 to 15 October 1993. This report is based on the discussions and conclusions of that meeting. EDITORIAL NOTE In preparing this publication press,for IAEAthe staffof have pages madethe up from the original manuscript views (s).The expressed necessarilynot do reflect those governments ofthe the of nominating Member States nominating ofthe or organizations. Throughout textthe names Memberof States retainedare theyas were when textthe was compiled. Theof use particular designations countriesof territoriesor does imply judgementnot any by the publisher, the IAEA, as to the legal status of such countries or territories, of their authorities and institutions or of the delimitation of their boundaries. The mention of names of specific companies or products (whether or not indicated as registered) does implyintentionnot any infringeto proprietary rights, should construednor be it an as endorsement recommendationor partthe IAEA. ofon the CONTENTS INTRODUCTION ........................................7 . COMBINATIO1 N PROCESSIN FOOF GO D INVOLVING IRRADIATIOT NA DOSES BELO..................................y kG 0 W1 7 . 2. SHELF-STABLE FOODS THROUGH IRRADIATION PROCESSING ......8 . 3. MICROBIOLOGICAL SAFET IRRADIATEF YO D SHELF-STABLE FOOD9 . S. 4. SUCCESSFUL RADIATION-STERILIZED SHELF-STABLE PRODUCTS ...1 1 . BENEFIT5 SHELF-STABLF SO EFOOE FOOTH DO DINDUSTRT Y AND CONSUMERS ..................................... 12 6. SHELF-STABLE IRRADIATED "MEDICAL FOODS" FOR AT-RISK PATIENTS — THE US EXPERIENCE .......................... 16 7. CONCLUSIONS ........................................ 18 APPENDIX A: MICROBIOLOGICAL SAFETY OF IRRADIATED SHELF-STABLE FOODS .........................9 1 . APPENDI : XSHELF-STABLB E MEAL COMPONENT SOUTE TH SH— AFRICAN EXPERIENCE .......................... 22 APPENDI : XPROCESC PRODUCINF SO G SHELF-STABLE, IRRADIATED FOODS ..................................... 31 REFERENCES ........................................... 32 LIST OF PARTICIPANTS ................................... 34 INTRODUCTION ConsultantA s Meetin Irradiation go Shelf-Stablr nfo e Food convenes swa evaluato dt e role f irradiatioth eo increasinn ni availabilitye gth , improvin qualite gth reducind yan e gth cost of shelf-stable foods; also, to consider the need for a research and development programm Joine th carriee ty b b FAO/IAE t o et dou A Divisio f Nucleano r Techniquen i s Foo Agricultured dan . The consultants were informed that the International Consultative Group on Food Irradiation (ICGFI), established unde aegie r th 1984FAO f n i so beeO s ,, ha IAEnWH d Aan compiling dat wholesomenesn ao f fooo s d irradiated with doses abov kGy0 1 e . Once eth compilation is completed, FAO, IAEA and WHO will be asked to evaluate these data and determino t e whether additional studies f anyi , , woul requiree db consideo dt r food treated with doses above 10 kGy to be wholesome. Within the scope of the meeting, it was agreed to define "shelf-stable" foods as those which have been prepared to have the capacity for long, safe storage under declared ambient conditions, without undue loss of nutritive value and of sensory acceptability. Such products may also include those which are sterile and suitable for medical purposes. For the purpose of this report irradiation will be a significant component of the process. 1. COMBINATION PROCESSING OF FOOD INVOLVING IRRADIATION AT DOSES BELOy kG W0 1 There is an increasing consumer demand for food which is safe, fresh or fresh-like, visually attractive, full-flavoured, nutritious, convenient to prepare and serve, with decreased f preservativeso e us , available throughou t reasonabl a e year d th t an , e a resultcost s A . , minimally processed, chilled foods have been marketed increasingl severan i y l advanced countries to satisfy consumer demand. Such foods, however, could introduce new microbiological risks, in view of emerging problems related to certain pathogenic microorganisms whic gron hca w under chilled conditions, e.g. monocytogenes,,L Yersinia, etc. Combination treatments involving irradiation could ensure the hygienic quality of products while retaining the quality demanded by the consumers. Developing countries require wholesome food with a prolonged shelf-life, often without the use of refrigeration. Irradiation in combination with other processes could result in products which can be distributed easily under tropical conditions. Combination treatments could als usee ob r improvin dfo microbiologicae gth l safet qualitd yan f cookedyo , chilled fooprepared dan d meals stored either under refrigeratio t ambiena r no t temperature. n ordeI o generatt r e data requiree foregoingth r fo d a Co-ordinate, d Research Programm Irradiation eo Combination i n with other Processe Improvinr sfo g Food Quality was initiatee Jointh ty b dFAO/IAE A Divisio f Nucleao n r Technique n Fooi sd an d Agriculture in 1991. The effects of irradiation at doses below 10 kGy in combination with other treatments, e.g. heat, low water activity, pH, modified atmosphere, salting, acidulants, packaging, etc. to bring about microbiological safety, unproved sensory properties, increased shelf-life and convenience in distribution and use, are being investigated. The results summarizee b y achievema r followsfa s d a o ds : 1.1. SHELF-LIFE EXTENSION OF MEAT AND FISH Irradiation investigated up to a dose of 3 kGy in combination with environmental stress factors, e.g , and/ow a . reduced r an sensoril H dp y acceptable acidulant humectantsr so , could substantially increas shelf-life eth fresf eo h mea poultrd an tthei d yan r products stored under chilled conditions. Normally, such products are stored and marketed under frozen conditions severan i l countries additionn I . , shelf-lif f semi-drieo e e enhancedb fisn ca husiny db g irradiatio combination i n with salting, dryin appropriatd gan e packaging. 1.2. MICROBIOLOGICAL SAFET FOOF YO D Low dose irradiation of ready-to-eat meals was found to be effective for controlling non-spore forming bacterial pathogens. Irradiating at doses as low as 1.5 kGy could be used for inactivating pathogenic microorganisms, e.g. V. vulnificus and V. parahaemolyticus which intrinsie seafooar w ra o ct d suc oysters ha clamd san s whic oftee har n consumed raw. 1.3. USE OF COMBINATION PROCESSES ON COMPOSITE FOOD AND PREPARED MEALS Irradiation up to a dose of 3 kGy improves microbiological quality of prepared meals composed of roast beef, gravy and certain vegetables and those composed of salmon, vegetables and dairy components, stored under refrigeration. A combination of an irradiation kGy5 treatmen4 heao d t ) an p t treatmen(u ) tresult 2 o t shelf-stabln 0 i valus1 (F tf o e e composite food mealan df superio o s r qualit o productt y s sterilize y eitheb d r hear o t irradiation alone. The suitability of various packaging materials for irradiated composite food and prepared meals are also being investigated. The above mentioned applications, which are being addressed through a co-ordinated research programme sponsored by the Joint FAO/IAEA Division, were considered to be outside the scope of this meeting. SHELF-STABL2 E FOODS THROUGH IRRADIATION PROCESSING Traditionally, shelf-stable foods have been produced by the food industries by the application of extreme techniques which are incompatible with high quality products. Examples include: heat sterilization, acidificatio valuesH p w ,lo severo nt e dryingf o e us , high salt levels in curing and use of added preservatives. In order to minimize damage to product quality, a strong trend in processing techniques in recent year s bee ha smovo t n e increasingly toward e applicatioth s f lesno s extreme processing, e.g. by the use of combination preservation techniques. This trend towards minimal processing can introduce increased risk due to reduction in the efficacy of inactivatio r inhibitiono f microbiano l pathogens. It is imperative that the assurance of safety that the consumer has come to expect and assum maintaineds ei .