IAEA-TECDOC-843

Shelf-stable foods through irradiation processing

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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 . Irradiatio integran a e b developmene n l parnth ca f o t systemw ne f o t s that target minimal processing and contribute to the maintenance of the expected and assumed degree of safety assurance. With respec o non-sterilt t e products, attention mus e givea b widt o nt e rangf o e vegetative and spore-forming pathogens. With respect to sterilized products, the key organism f concer so varioue th e nar s type f Clostridiumso botulinum.

meetine Th g paid particula f irradiatioo r e attentious e t doseth na o nt s abov kGy0 e1 , in combination with other processes, which would result in shelf-stable products (i.e., which can be stored without the use of environmental control for a significant period of time). Wit e phasinf chlorofluorocarbonth o h t ou g s (CFCs) whic e widelar h e y th use y b d refrigeration industry for food distribution, there is a need to evaluate the potential for the developmen f producto t s distributee whicb n hca marketed dan d without refrigerationn I . many developing countries, the phasing out of CFCs would result in less availability of food of animal origi wels na highe s a l r cos f suco t hlocae footh lo d t population . Therefore, there is an increasing interest in such prepared shelf-stable meals which are currently marketed under frozen or chilled conditions. An investigation should be made of the market potential for such product t ambiensa t temperature using combination treatments involving irradiation.

A variet f shelf-stablyo e food products would also attrac interese th t f severao t l target groups e.g., yachtsmen, campers, hikers, mountain climbers thosd receivo an , ewh e food through emergency relief operations. Irradiation could result in high quality shelf-stable food especially thos f animao e l origin r thesfo , e population groups. Such foods have been successfully used by astronauts and armed forces personnel in some countries.

Another typ shelf-stablf eo e food product radiation-sterilizee sar d meals intended mainly for medical use (eg. by hospitals for organ transplant patients) and other vulnerable groups of individuals under medical care. While a few countries (Finland, the Netherlands, U.K and South Africa) specifically permit radiation-sterilized food for such uses, the availability of such food is very limited.

. MICROBIOLOGICA3 L SAFET IRRADIATEF YO D SHELF-STABLE FOODS

3.1. STERILE FOODS

In the context used here shelf-stable food is food that has been processed in such a manne extenden a rs thaha t di t shelf-life without environmental control (see definitioe th n ni Introduction). Because such product storee sar d under conditions that will suppor growte tth h of pathogenic microorganisms, means mus providee tb d eithe preveno rt growte tth sucf ho h organisms or to eliminate them from the food product entirely. Of conventional technologies only retort processing will eliminat l pathogenieal c microorganisms fro fooe onld mth d an y e expensth t a f changino e e nature foodgth th f .o e Treatmen e footh df o twit h ionizing radiatio n eliminatca n e eve e mosth n t resistan f foodborno t e pathogens, Clostridium botulinum, from food without deleterious qualit effecte foode th th . botulinum n f C o s.yo s i the primary concern because of its resistance to radiation and heat, and its potential for toxin production, and because most of these products will be canned or packaged in air- impermeable pouches thereford an , definitioy eb storee b y t ambienda nma t temperatures. Irradiation processing intende o eliminatt d . botulinumC e will also eliminat l otheal e r bacterial pathogens suc Clostridiums ha perfringens, Bacillus cereus, Staphylococcus aureus, Salmonella spp., Campylobacter spp., Listeria monocytogenes, Aeromonas hydrophila,d an Escherichia coli 0157:H7 (Table I). In addition parasitic organisms will also be eliminated. TABLE I. RADIATION RESISTANCE OF COMMON FOODBORNE PATHOGENS

Organism Substrate Irradiation 12D-Value Reference temperature kGy

A. hydrophila Beef 5°C 1.7 16 C. botulinum Beef -30±10°C 37.0 8 C. botulinum Beef -30±10°C 41.2 5 C. jejuni Beef -5°C 5.28 15 . coliE O157:H7 Beef C ° 5 0- 1.93 19

C. botulinum Pork ambient 43.3 1 C. botulinum Pork -30±2°C 43.7 7

C. botulinum Chicken -30+2°C 42.7 7 C. jejuni Turkey 0-5 °C 2.23 15 L. monocytogenes Chicken 2-4°C 9.24 14 S. aureus Chicken 0° 4.32 18 S. enteritidis Chicken 2°C 7.10 20 typhimuriumS. Chicken 2°C 4.72 20

C. botulinum Bacon 1.7-10°C 26.5-28.7 4

C. botulinum Ham 2-5 °C 29.0 2

C. botulinum Corned beef -30°C 25.7 3

C. botulinum Pork sausage -30°C 23.9 3

10 3.2. NON-STERILE, SHELF-STABLE FOOD

Shelf stability may be attained by a number of methods. Such food may be contaminated with foodborne microbial pathogens that could be eliminated by treatment with ionizing radiation sucn I . h foo growte dth potentiad han l toxin formatio spory nb e forming bacteria will be inhibited by standard food technological methods such as by reduced water activity. Salmonella, Staphylococcus, Listeria, Aeromonas, . E coli O157:H7d an , Campylobacter can all be eliminated by treatment with ionizing radiation doses generally not exceedin kGy0 g3. . Such infectious parasite s Toxoplasmaa s gondii, Trichinella spiralis, Cysticercus bovis, and Cyslicercus cellulosae will also be inactivated by very low doses of radiation.

4. SUCCESSFUL RADIATION-STERILIZED SHELF-STABLE PRODUCTS

Mea seafood an t d product exceptionaf so l high quality have been produce used dan n d i Soutd an hA AfricaUS e th . These products include:

1. Food used during manned space flights

Dose range (kGy) Beefsteak 37-43 Corned beef 25-29 Turkey slices 37-43 Ham 37-43 Pork sausage 27-33 (Ref. E.S. Josephson, 1983. Radappertizatio meatf no , poultry, finfish, shellfis speciad han l diets. In "Preservation of Food by Ionizing Radiation" Vol III, E.S. Josephonson and M.S. Peterson (Eds) PressC CR . , Boca Raton, Florida).

. Radappertized2 Foods Developed ArmyS U y b Natick Laboratories,A Natick,US , MA

Dose range (kGy) Roast beef 37-43 Beef steak 37-43 Ham 37-43 Corned beef 25-29 Turkey slices 37-43 Pork sausages 27-33 Chicken 45-54 Cooked salami 25-27 Shrimp 38-49 Codfish cake 32 (min.) Bacon 25.2 (min.) Pork shop 43.7 (min.) (Ref. E.S. Josephson, 1983. Radappertizatio meatf no , poultry, finfish, shellfis speciad han l diets "Preservation I . f Foono Ioniziny db g Radiation l III"Vo , E.S. Josephso M.Sd nan . Peterson (Eds). CRC Press, Boca Raton, Florida).

11 Shelf-stable3. irradiated food developed Southin Africa

Meat Dishes Starches Vegetables

Meat loaf Stir-fry rice Peas Smoked Viennas Maize meal porridge Tomat onioo& x nmi Roast chicken Sweet potatoes Baby carrots Country sausage Kidney beans Baby carrot peas& s Beef curry Yellow rice Cabbage Chicken and tomato White rice Mixed vegetables Chicken casserole Savoury white rice Sweetcorn Bobotie Stir-fry wheat Beef steak in gravy Savoury yellow rice Chicken stew Smoked chicken Boerewors Steak Meat balls Chicken curry Beef stew Roast beef Hamburgers

f theso e e us food e bees Th ha sn limite lacy db f nationa ko l regulations r exampleFo . , no general clearanc radiation eo n sterilized foo bees PDAS Soutdha n U I n .e givehth y nb militare th y b ye Africa doe us requirt e sno th , e special regulation specifiy b e us ct groupsbu s of other personnel (yatchsmen/expeditions) on the basis of need requires permission from national authorities.

5. BENEFITS OF SHELF-STABLE FOOD TO THE FOOD INDUSTRY AND CONSUMERS

e majoritTh f fooo y d preservation procedure y inhibitingb st currentlac e e th us n yi growth of microorganisms to varying extent (Table II). These procedures include, for example: the use of low temperature in chill, 'superchuT and frozen storage; reduction in pH value by addition of specific organic acids; reduction in water activity by the addition of salts, sugars or other solutes, or by drying oxygen-free, vacuum or nitrogen packaging; carbon dioxide-enriched modified atmosphere packaging; and addition of organic or inorganic preservatives.

In contrast, few procedures are used that act by inactivating the microorganisms of food-poisoning or food spoilage concern. Heat remains by far the most commonly-used inactivation technique.

With regard to effective control of food-borne pathogens, it can be argued that improved and new inactivation techniques, targeting microorganisms of concern rather than minimizatio r 'inhibitionno f theio ' r growth urgentls i , y require consumef di e r b safet o t s yi maintained or unproved.

12 TABLE II. CURRENT AND POTENTIAL FOOD PRESERVATION TECHNOLOGIES

Objective Factor Mode of achievement/example Slowing dowr no Lowered temperature Chill-storage inhibition of microbial 'Superchiir storage growth Reduced water activity/raised Drying and freeze-drying osmolality Curing and salting Conserving with added sugars Microstructure control Compartmentalisatio f aqueouno s phases in water-in-oil emulsions Decreased oxygen Vacuum and nitrogen packaging Increased carbon dioxide Carbon dioxide-enriched 'controlled atmosphere' storage or 'modified atmosphere' packaging

Acidification Additio f acids/fermentationo n

Use of cultures Additio microorganismf no d san culture products

Alcoholic fermentation Brewing, vinification Fortification

Use of enzymes Addition of: - lysozyme - lactoperoxidase

Use of preservatives Addition of preservatives: - inorganic (e.g. sulphite, nitrite) - organic (e.g. propionate, sorbate, benzoate, parabens) - antibiotics (e.g. nisin, pimaricin)

13 TABLE IL (cont.)

Inactivatiof no Heat Pasteurization microorganisms Sterilization

Ionising irradiation Radurization Radicidation Radappertization

Chemicals Treatmen f ingrediento t s (e.g. with ethylene oxide) Treatmen packaginf o t g materials (e.g. with hydrogen peroxide, and/or heat, irradiation)

Enzymes Addition of lysozyme

Pressure Application of high hydrostatic pressure

Electric shock Application of high voltage pulses

Restrictio f accesno f so Packaging Aseptic processin packagind gan g microorganisms to foods Aseptic processin\ g without recontamination

Gould, G.W. (1989). Mechanisms of Action of Food Preservation Procedures. Elsevier Science Publishers, London.

5.1. INACTIVATION VERSUS INHIBITION

The number of reported cases of food-borne illness continues to rise in developed and underdeveloped countries although the means for control of the growth of pathogens in foods relativelw no e ar y well-known. Whilst major outbreak oftee sar n traced bac sourceo kt e th , majority of cases are sporadic and seldom traced to source.

Most sporadic cases are thought to occur as a result of lapses of hygiene, e.g., in the e caterinth homn i gr eo establishment . However underlyine th , g reaso sucy nhwh lapses cause problem occurrence th s si organisme th f eo thosn si e environment firse th t n si place ; e.g., enterin e hom gth n contaminate o e d foods. Lapse f hygieno s e will always occur. Substantial progres reductioe th n si food-bornn ni e disease will therefore onl achievee yb d if techniques are introduced to prevent the organisms of concern from entering the home or catering environments.

That being so, a major target for research must be the development of more effective inactivation techniques. Techniques for growth inhibition should be given priority only in those instances where inactivation is judged to be impractical.

Irradiation y procesofferke a ss that shoul e integrateb d d wite otheth h r available techniques to inactivate targeted organisms from those foods which present greatest risks.

14 5.2. PREDICTIVE MODELLING OF MICROBIAL SURVIVAL, IN ACTIVATION AND GROWTH

Means for the inhibition of microbial growth in foods are reasonably well-developed and facilitate increasine th y db g availabilit f predictivyo e microbiology models. These ear generally constructed from experimentally-derived data on the effects of factors such as temperature , concentrationw a , pH , f saltacidsd o s an s , gases, e growtetc.th d n ,o an h survival of microorganisms. The models can then be interrogated to generate predictions of the effects of changes and of combinations of factors. These predictions are of potentially great value to the food industries. They allow confident derivation of safe, stable, new or modified foods, processe distributiod san n systems, withou neee time-consuminr tth dfo d gan costly inoculated pack studies or challenge testing. Predictive models accessible to the food industries are being developed in the USA, the UK, Australia, and in Europe in an Economic Union-funded project including ove laboratorie0 3 r countries1 1 n si .

e includeb Irradiatioo t t thesn i dye es predictivnha e model a facto s a s r affecting microbial growt survivald han . Applicatio f irradiationo fooe th dy nb industrie s woule db greatly encouraged if irradiation were included in such models. A research initiative to build up an irradiation models base could, therefore, be attractive and rewarding.

5.3. 'NUDGING' FOOD PRODUCTS TO SHELF-STABILITY

Many long chill-stable or limited ambient-stable foods that are marketed currently aroun worle d th close e dar completo t e shelf-stability somn I . e instances small changes, e.g, formulationo t , processin r packagingo g have been sufficien 'nudgeo t t ' such producto st complete shelf-stability mann I . y such products, irradiatiopreferrea e b y dnma routo et supply the 'nudge'.

Examples where ambient-stabilit bees yha n so-achieved include so-callee th : d 'SSP' (shelf-stable products) meat products, in which proper control of water activity ( < 0.95) with nitrite and "in-pack" pasteurization ensures stability; fermented dry sausages in which formulation just below aw0.82 ensures that oxygen-free packaging stops the growth of spoilage yeasts that would otherwise grow at aw values down to near aw 0.6; intermediate moisture fruit piece whicn si h vacuum-packin milr go d heat pasteurization likewise controls growt f yeastho mouldsd san .

In many such instances, irradiation could be an industrially attractive adjunct that would provid e 'nudgeeth achievo t ' e ambient stabilit thid ysan woul mose db t attractiv thosn ei e instances in which a definite organoleptic advantage resulted. For example in allowing minimal heating and consequent minimal damage to product quality (eg. of a meat snack product); in allowing intermediate moisture fruit pieces to be formulated at higher aw and hence moisture levels than previously, with advantages regarding yiel textured dan .

A possible targe r researcfo t h that would encourag e developmenr th eo w ne f o t improved ambient-stable foods world-wide could, therefore concentrato t e b , e effor sucn o t h foods, typical of different countries, that are nearly shelf-stable. Techniques such as pasteurization, modified atmosphere packaging ,e sufficien b etc. y ,ma somn i t e caseo t s 'nudge' such product shelo t s f stability othersn I . , irradiatio offey nma r advantages with respect to sensory quality, presentation and safety.

15 5.4. OVERCOMING FOOD INDUSTRY RELUCTANCE

reluctance Th foof eo d industrie includo st e irradiatio thein i r portfolio proceduref so s for preservatio safetd nan y coul overcome db numbea y eb f actiono r addition i s thoso nt e that attempt to overcome the reluctance of consumers and retailers to accept irradiated foods. These actions include:

• A new concentration on inactivation as the only viable route to achieve a real reduction foon i d poisonin generae th n gi l population deliveo t d an ,r highly decontaminated foods for special purposes, e.g., patients on immunosuppressive therapy. integratioe Th irradiatiof • no factoa predictivs nw a r ne inte oth e microbiology models databases thabecomine ar t g available worldwid r fooefo d industro d r fa yo s use d an , not include irradiation.

e specifiTh c « targetin f long-chilgo limited-ambiend an l t stable foods worldwidr fo e which irradiation could provide a sensorially-advantageous 'nudge' to extended ambient- stability.

. SHELF-STABL6 E IRRADIATED "MEDICAL FOODSR "FO AT-RISK PATIENTS — THE US EXPERIENCE

Fro e earlmth y 1950 o arount s d 198 e 0Uniteth d States Army food irradiation programme developed methods and technology for the production of shelf-stable, radiation- sterilized meal components of high eating quality, nutritional value, safety and stability, even under extreme ambient temperature/humidity storage conditions. Thes principalle ear y 'dry- packaged' (i.e. withou gravya t , sauc brinr eo e since unlike canning heao n , t convectios ni required) meat, poultry and seafood items, hermetically vacuum sealed in multi-layer aluminum foil pouches that provide a total barrier against air, moisture and microbe transmission. These products were developed by the Army for use as field rations; however, they can equally serve as foods for medical patients who require sterile diets, and other 'niche markets' that nee r prefedo r long-term shelf stable foods offering high qualitd yan safety acceptabln a t a , e priceoccupationan a n i , r recreationao l contexte lus procese Th . s si describe Appendin di . xC

6.1. RADIATION-STERILIZED PRODUCT USE

Such products can be eaten directly out of the pouch, or they can be first warmed in a microwave oven after removal from the pouch, or, by a conventional heating unit either in or out of the pouch. Although they were developed by the US Army as field rations, they usee b such s da o t hav t , eye excep largn i t e scale military feeding trials, becausS U s i t ei Army polic purchaso yt servd ean e only foods thae PDA-approvear t d and/or ro thae ar t could be in regular commercial production for the mass civilian consumer market in the USA r radiation-sterilizeFo . d e widelfoodb o t sy available S Food DruU an de gth , Administration would have to be petitioned formally for their approval, which is a complex and lengthy process.

However speciae th n i , l cas radiation-sterilizef eo d shelf-stable food dies sa t components for at-risk medical patients ("medical foods", e.g. r immuno-compromised/suppressefo , d bone marro d orgawan n transplan r AIDo t S patients a recommendatio) a Join y b nt

16 FAO/IAEA/WHO Expert Committe Foon eo d Irradiation (JECFI theio t s r)a wholesomeness, and/or the US-FDA standard petitioning-and-approval process, for example, should not be necessary. In fact, a few countries (Finland, Netherlands, UK) have already approved radiation-sterilized meals for medical use, although these approvals have yet to be implemented. Also, as noted elsewhere in this consultants meeting report the Republic of South Africa has adopted the rnethodology worked out under the US Army programme and has done considerable radiation-sterilized shelf-stable product development/formulation, also in the context of military feeding, and can make a wide variety of such products available on order.

Regulatory actions may occur in the USA to approve such products for medical use for followine th g reasons ) lik countriesl seein(1 :s e i al many S t increasn U ga no e e f i ,th th , n ei numbe f medicao r l patient otherd san s with wea r non-functioninko g immune systemo swh should be or must be on sterile diets, (2) the American Medical Association (AMA), whose physician members woulonee th prescrib o st e db e radiation-sterilized food theio t s r patients, supports food irradiatio abilits it r eliminatno yfo t e pathogenic microorganism therebd san y help protect public US-FDhealthe th ) mechanisa (3 ,s Aha approvar mfo speciaf lo l "medical foods" (e.g., foods formulate havo dt e specific nutrient composition speciar sfo l needs) and, ) ther(4 e have already bee limitedo ntw t verbu ,y successful experiences with radiation- sterilized meal components in the USA. For nearly twenty years the US National Aeronautic Spacd an s e Administration (NASA bees ha ) n using several radiation-sterilized mea poultrd an t y item mannen so d space flights thesd an ,e have been very popular wite hth astronauts. Also, at one US hospital, the Fred Hutchinson Cancer Research Center, Seattle, a variet f radiation-sterilizeyo d food items were consume bony db e marrow transpland an t other immune-suppressed patients with much success ove perioe rth d from 197 1988o 4t .

The radiation-sterilized meal components used by NASA and by the Fred Hutchinson Hospital came unde speciara investigationaA PD l l food/drug approva not-yet-approver fo l d items (since irradiatio s treatei n d regulation-wis a foo s da e additiv e USAth n i e, each irradiated food must receive formal PDA clearance for general use). In 1988 the Fred Hutchinson Hospital discontinued their use, as a small research irradiator used for their sterilizatio nearbe th t na y Universit Washingtonf yo , Seattle, becam weao eto deliveo kt e rth required high dos reasonabla n ei e perio nexe th timef dto d closesan , r t irradiatofa o to s rwa awa r practicayfo l use. Because products thermally processe same th eo dt high degref eo sterility are of too-low-an eating and nutritional quality, the Fred Hutchinson Hospital reverted to "low bacteria-pathogen free" diets that must be indiv-idually tested to assure freedom from pathogens before serving. Such foods could als producee ob substeriliziny db g irradiation to markedly reduce overall microbial counts while assuring freedom from common non-sporeforming pathogens such as the Salmonellae. Irradiation of raw poultry to well below the sterilization level to render it virtually pathogen free, has already been approved in the USA and in several other countries, with limited production and distribution in the USA. In principle, such pathogen-safe (subject to testing) product could be used by hospitals or high risk individuals.

Whenever shelf-stable radiation-sterilized food has been approved as "medical food", it could create a niche market and incentive for the industry to develop shelf-stable radiation- sterilized foo r hospitalfo d "high-risd an s k individuals". Such shelf-stable, sterile products could also find other, non-medical 'niche markets' that would require full regulatory approval througs a , USFDe hth A petitioning process.

17 7. CONCLUSIONS

e productioTh f shelf-stablo n e food using irradiatio n combinatioi n n with other processes would result in increased variety, improved quality and would facilitate wide food distributio n boti n h advance d developinan d g countries. While consumer n advancei s d countries woul more db e intereste varietye th n i d , convenienc qualitd ean f sucyo h food, those in developing countries would benefit from such products which can be marketed f refrigerationo withoue us e meetingth e t Th . , therefore, agreed that:

1. Technology for producing shelf-stable irradiated food is well established and a number of such products exist, som f whiceo sterilee har .

2. Some food products exist that could be made shelf-stable using irradiation at doses below 10 kGy.

. 3 Under special permission r regulationso s , opportunities exis o supplt t y shelf-stable irradiated sterile food to hospitals and individuals on a physician's order.

. 4 Food irradiation processing technique t includeno e predictivar n sdi e microbiological safety model databases, thereby reducing their accessibility to potential users. This needs to be corrected. e concepTh f eliminatio o . t 5 f undesirablo n e microorganisms shoul e e linkedb th o t d present statu f riskso assessment foon i d retailing.

6. The concept of shelf-stable meals should be abandoned in favour of shelf-stable meal components, thereby:

) (a allowin permutatioga f meano l component achievo st e dietary flexibility. (b) avoiding problems associated with diverse processing requirement overald an s l resulting variabilit shelf-life th f yo f componentso e .

18 Appendix A

MICROBIOLOGICAL SAFET IRRADIATEF YO D SHELF-STABLE FOODS

1. STERILE FOODS

contexe th n I t used here shelf-stable foo foos i d d thas beeha t n processe sucn di ha manne extenden a rs thaha t i dt shelf life without environmental control primare Th . y concern about shelf-stable food thas i s t pathogenic bacterial spore-forming genera Bacillie th , d an Clostridia mus e killeb t r preventedo d from increasin numbern gi producind an s g toxin during storage. Clostridium botulinum usualls i ytese useth t s organisda m becauss it f eo resistance to radiation and potential for producing toxin, and because most of these products wil cannee b l r packagedo air-impermeabln di e pouche definitioy b storee b d y san t da nma ambient temperatures. Meat products wile enzyme-inactivateb l y heatb d , which will eliminate many spoilag pathogenid ean c bacteria substrate Th . alsy oema affec survivae th t l opathogena f resulte Th . f studiesensitivitso e th f . botulinumso C f yo severan i l different type f productso describee sar d below:

Beef: El-Bisi (1966) investigated the survival of C. botulinum spores in cooked vacuum canned cooked cubed beef round at temperatures from -196 to +20°C. He found that gamma irradiation temperature had little effect on the rate of spore inactivation below -80 °C and a small effect above -80°C. Grée. (1971al t ze ) determine effece dth f gammo t a irradiation temperature on the survival of inoculated C. botulinum spores in vacuum canned autoclaved ground beef. Spore resistance progressively decreased with increasing irradiation temperature between -196 to 95°C. Anellis et al. (1975) conducted an inoculated, irradiated beef pack (1,240 cans) study. Each can contained a mixture of 107 spores from 5 type A and 5 type B C. botulinum strains cane Th .s were irradiate± 10°e gamm 0 th C-3 s a t dusina o g^C source. After irradiatio month6 canr e examinend fo th ssan C wer2° r e± d fo store 0 3 t da swelling, toxicity, and recoverable botulinal cells. The minimal experimental sterilizing dose based on nonswollen, nontoxic product was 22 to 26 kGy. The 12D dose was estimated to kGy7 3 .e b

Anellis et al. (1979) evaluated the dose necessary to reduce the number of viable spores of a single most resistant strain of C. botulinum by 12 log cycles in vacuum canned, enzyme- inactivated beef. The meat (40+5 g/can) was inoculated with 107 spores per can of a spore mixture of C. botulinum 33A, 36A, 62A 77A, 12885A, 9B, 40B, 41B, 53B, and 67B. The samples were gamma irradiated (0, 14, 18, 22, 26, 30, 34, 38, 42, 46, and 50 kGy) at -30±10°C. The inoculated pack study (1100 cans) had only one partial spoilage point at 22 kGy, and the binomial confidence limit method was used to estimate a 12D dose of 41.2 kGy.

Pork: Anelli . (1969al t e s ) conducte inoculaten da d pack study with 5690 canf o s enzyme-inactivated pork loin inoculated with 106 C. botulinum spores per can. Each lot was seeded wit hdifferena t strain; fiv efivd typean typeA straineB s were used cane Th .s were gamm aintervaly irradiate kG 25°o t 5 kGy 0 s5 5 n Ci t ,fro o da t incubatem0 x si r dfo months at 30°C, and examined for swelling, toxicity, and recoverable C. botulinum. The 12D dose was estimated to be 43.3 + 1.7 kGy. Anellis et al. (1976) conducted inoculated pack studies with irradiated pork (2300 cans) to establish the gamma-irradiation (-30 + 2°C) 12D dose using inocula of 107 spores per can of a mixture of 5 type A and 5 type B C. botulinum strains. After irradiatio e cannth s were incubate month6 r tested dfo an r s dfo swelling, toxicity, and recoverable botulinal cells. The minimal experimental sterilizing dose

19 base flatn do , nontoxi valuc D estimates produc 12 porkr e wa e 30-3s fo y Th .wa t o d t 2 kG t porkr +5-to-25°Cba fo e d 43.y .an Notvalue7kG 0 D similarit e -3 e12 th t sa e . th f yo

Chicken: Anelli . (1977bal t e s ) conducted inoculated pack studies with irradiated chicken (2000 cans) to establish the gamma-irradiation (-30 + 2°C) 12D dose using inocula . botulinum typ5 C mixtura d f eB o typ5 an n f 7 sporeeA o ca o10 fr strains spe . After irradiation the cans were incubated for 6 months and tested for swelling, toxicity, and recoverable botulinal cells minimae Th . l experimental sterilizing dose base flatn do , nontoxic produc dos estimates chickenr D 40-4s fo e12 wa y e wa t 2t 42.kG Th d. a 7 kGy.

e firsth t f o mea e Bacont on product s e studiewa b : o t s d extensivel r possiblfo y e commercial ionizing radiation treatment s selectewa t I .d becaus s relativelit f o e y short refrigerated shelf life cannot i ; thermalle tb y processed without undesired change sensorn si y properties t withstandi ; s relatively high radiation doses without significant los sensorn si y quality attributes; it is a poor substrate for growth of C. botulinum; and it was targeted for reductio contentd f nitritnan o e eus . Anellis et al. (1965) reported that the 12D gamma-radiation dose for sterilization of sliced, cured bacon, packe vacuan di cann challengei d san d with approximatel 6 sporey10 s of C. botulinum types A and B per can, was 26.5-28.7 kGy . The minimal sterilizing dose wa kGy 0 authore s2 Th . s observed that viabl . botulinumeC spores could surviv t leasea 8 t months in storage at 30 °C without producing detectable spoilage or toxin production at doses belo kGy0 w2 .

Ham: is frequently temperature-abused and has been the subject of several food irradiation studies. Prat Ecklund tan d (1956) reported that irradiate kGy4 d(2 d ) ha cure m dha bese th t flavoumeay an tf o testedr . However, Erdma Wattd nan s (1957) irradiaten i m dha observed an r ai d severe colour losses, off-odours marked an , d change nitritn i s e levels. Reduction nitritn i s e were eventually advantageouse founb o t d productd an , s with good sensory properties were produced (Wierbicki and Heiligman, 1973; Wierbicki et al., 1976).

The microbiology of irradiated hams was investigated in a series of studies (Anellis et al., 1967; Drake et al., 1960; Greenberg et al., 1965). Anellis et al, (1967) conducted a large-scale (6350 cans) inoculated-pack study of ham, which was gamma irradiated at 5.0 kGy intervals from 5.0 to 45 kGy. Each can was challenged with approximately 106 spores and vacuum sealed. The temperature at the start of the irradiation process was 2 to 5°C and was not permitted to rise above 24°C. A dose of 45 kGy was an adequate sterilization dose. Lot f 100o s 0 can r dosspe e tha r higheto receivey rkG dose5 d3 s were unswollen, nontoxic, and sterile. A few cans (5/2000), which had received doses of 25 or kGy0 3 , contained iner t recoverablbu t e spores straihighesy e s an dosTh . D nr wa 12 efo t 29.0 kGy.

discovere Th y thaorganoleptie th t c propertie coulm greatle ha d b f so y improvey db enzyme inactivatin producte gth , packagin vacua,gn i irradiatind an cryogenit ga c temperature (-30°C), coupled with a reduced nitrite concentration in the cure, required a reassessment radiatioD 12 e oth fn dose (Anelli al.,t se 1977a). This inoculated-pack study (1500 canf so ham) establishe . botulinum,valuD C dr 12 etha fo e tth assumin normag lo ga l rat kilf ef o o l 6 spores/ca10 e moson tf o nresistan t kGy2 e 3 inoculustrain s Th . wa ,r thi mfo s study consiste fivd typ5 ean f typdeA o strainseB 6 spores/strain10 , .

Corned beepord fan k sausage Anelli . (1972al t se ) reporte valueD d12 t s-30°a Cn i vacuo for corned beef and pork sausage of 25.7 and 23.9 kGy.

20 The spore formers are the most radiation resistant of the bacterial foodborne pathogens . botulinumdoseanD C r d12 sfo effectively inactivate other bacterial pathogens examplr Fo . e valuD Aeromonasr 12 e fo e th hydrophila been i approximatels i f (Palumby kG 7 y1. t al., oe 1986). Campylobacter jejuni has a 12D value of approximately 1.2 kGy in ground turkey (Lambert and Maxcy, 1984). Escherichia coli O157:H7 has a 12D value of approximately 5.28 kGy at -5°C on beef (Thayer and Boyd, 1993). Listeria monocytogenes has a 12D value of 9.24 kGy at 2-4°C (Huhtanen et al, 1989). Salmonella spp. have 12D values of 4.56 to chicken o y 9.2 nkG (Thaye4 C mea , 0° Staphylococcus 1990d t al ta t an re ) D aureus12 a s ha value of 4.32 kGy at 0°C on chicken meat (Thayer and Boyd, 1992).

. NON-STERILE2 , SHELF-STABLE FOOD

Shelf stabilitobtainee b y numbea y ma db f methodo r s mos t resulf whico tno o thd insterila e product. Such foodbecomy ma s e contaminated with foodborne pathogens that could be inactivated by treatment with ionizing radiation. In such foods the growth and potential toxin formation by spore formers will be inhibited by standard food technological methods suc reduces ha d water activity. Salmonella, Staphylococcus, Listeria, Aeromonas, E. coli O157:H7, and Campylobacter can all be eliminated by treatment with ionizing radiation doses generally not exceeding 3.0 kGy. Toxoplasma gondii, Trichinella spiralis, Cysticercus bovis, Cysticercusd an cellulosae will als eliminatee ob very dosedb w ylo f so radiation. The radiation 12D-values for a number of common bacterial pathogens in meat or poultr summarizee yar Tabln di . eI

21 Appendix B

SHELF-STABLE MEAL COMPONENTS- SOUTE TH H AFRICAN EXPERIENCE

1. INTRODUCTION

During the late 1970s and early 1980s the Atomic Energy Corporation of South Africa (AEC) undertoo developmene kth shelf-stablf to e mea militarty productb e us yr personnesfo l under special conditions. The initial request was for raw meat that could be kept at room temperatur cooked ean d when needed. After initial experimentatio founs wa dt ni that although meae sterils th wa t s structureit degrades ewa enzymy d b necessars wa et i activito ys d yan to examine a process involving pre-cooking. Use was made of data accumulated by the US Army Laboratories at Natick in the 1950s but these data were optimized for local use.

Following success in the area of meat processing the AEC was requested to extend their area of interest to include starches and vegetables.

198n I 9 further wor requestes kwa supplo dt y meal component Orthodoy b e us r xsfo Jew militarn i s y servic thao es t they migh deployee b t fiele th dn di beyon e reacdth f ho Kosher food supplies. A special Kosher processing line was developed for this purpose.

enablo T constructioe eth suitablf no e meals from component evaluatioe sth variouf no s accompanying sauce s investigate wa sthrougC AE s linky hit db s wit e Universithth f yo Pretori Councie a th (UP d r Scientifian )fo l Industriad can l Research (CSIR) laboratorien si Pretoria.

2. PROCESS METHODOLOGY

2.1. Mea poultrd an t y components

basie Th c procedur summarizee b use n dca Fig.ln i s da .

Coo attaio kt n internal temperatur least 77°f a minuteeo 0 r 1 tC fo s inactivato (T e enzymes) I Chill in blast chiller (To make handling and vacuum packaging easier) ; Slice or portion (if needed) I Vacuum pack 1 Freeze to -40°C (Mechanical, about 8 h) 1 Irradiate at 45 kGy (or as recommended by the US Natick) at between -40°C and -20°C producf o p to totes n i tn o )e ic y (usdr e i Incubate at 38°C for 10 days I Vacuum pack in 4 layer laminated flexible pouches (Nylon/Foil/Polyester/VLDPE)

Fig.l. Basic procedure for the processing of meat and poultry.

22 Soute Th h African Burea Standardsf uo , being inexperience thin di s typ processingf eo , insisted that the total production output be incubation-verified and not just a percentage, as is common for the canning industry.

Customer requirements place maie dth n emphasi developmene th n so f wholo t e meat rather than comminuted products such as the turkey rolls or codfish cakes that the US Army Natick Labs originatedd ha , .

Microbiological testing was carried out on all products prior to sensory evaluation to confirm product sterility and safety. In most cases either a trained panel or the process operators o werwh e, experience t necessarilno t bu d y trained, e sensorcarrieth t ou yd evaluation. Statistical evaluations of results were carried on processed meats, where appropriate t starchebu , vegetabled san s were graded onl acceptabls ya unacceptablr eo d ean no other statistical data are available.

2.2. Fish

Some processing of fish was attempted using the described method but with little success.

2.3. Starches and vegetables

2.3.1. Vegetables

Initial studies were carried out by cooking certain vegetables, which were then processed furthe wits a s founmeatse r hth wa dt I . thaproducte th t s become very d sofan t mushy after processing. Subsequently, the products were only blanched and then packed, froze irradiatedd nan .

An extensive experimen thes nwa t undertake teso nt t virtuall l availablyal e vegetables.

2.3.2. Starches

Initial work with starches showed that they became very d mushsofan t y after processin thereford decides gan wa t i eonlo d t y partially coo klatee theth rr mstudiesfo . Subsequent work was carried out using white rice and two pasta types, i.e. shell noodles and spaghetti producte Th . s were partially cooked, som othed ean chillerC froze7° o dt -7°Ct na , -40°C-18°d productan e C Th . sabove werth t a ee temperaturesy irradiatekG 5 4 t da e Th . irradiatio Gammabea e temperature th carrie s th n i d n wa t an dou 0 me65 could therefore eb maintained as required. The products were then stored at room temperature until required for sensory analysis. Control samples were frozee differenth t a n t temperature kepd an st frozen until require r evaluationdfo .

2.4. Ethnic meals

The basic layout of procedures is as given in Fig. 1. All meats and starches were precooke s discussea d d earlier. After being cooke chilledd an d , they were then further processed as in Fig. 1. All vegetables with the exception of the cabbage and tomato and onio werx nmi e bought commercially frozen, weighed into portions t int packete pu ,o th n si frozee th n state, vacuum sealed, froze -40°o n t irradiated d Can cabbage Th . boughs ewa t fresh from the market, washed, sliced and boiled for a few minutes until just soft, drained,

23 chille thed dan n packe processed dan describeds da tomate cookes Th onio.wa d ox an d nmi in a tilting frying pan with a number of ingredients, chilled, packed and processed as before.

2.5. Sauces

Initial problems in meal component process development has been restricted by failure of starch based thickeners mainly due to the freezing step in the process. Work by Louw (1991) identified thi concentratew s no proble s i d mdevelopmenn an do f protein-baseo t d thickness especiall mear yfo t sauces.

. RESULT3 S

3.1. Meat and poultry components

A number of meat dishes were developed successfully and these can be divided into five groups.

(a) Whole meats cooked in convection ovens, chilled, sliced and packed with or without gravya ; e.g., roast beef slices with gravy ,f por o roas kg le tslice s with gravy, roast chicken breasts with mayonnaise sauce and bacon.

(b) Steak or hamburger patties, boerewors (beef sausage ) fried in a tilting frying pan, chilled and packed with or without a tomato and onion sauce.

(c) Ground meat products, where the meat was precooked in the tilting frying pan, the final produc "assembleds twa ovene th baked n i , "an f chilled dof , portione packed dan d e.g. boboti locaa e( l minced meat dish), meat loaf, meat ball lasagnad san .

(d) Casserole dishes where the product was stewed in a tilting frying pan, chilled and packed, e.g. beef curry, beef stroganoff, beef stew, chicken curry, chicken and vegetable stew and chicken and tomato casserole.

(e) Commercially processed items that were bought, packed, frozen and irradiated, e.g. country sausag Frankfurtea e( r type sausage), smoked Vienna smoked san d chicken.

General comments on meat dishes

In all cases, meat with low internal muscle fat has been used and excess fat trimmed off the outside of roasts before cooking.

Bot bobotie hth lasagnd ean a have final toppings consistin f milgo k based saucet sbu hi the small quantity used these sauces do not pose any sensorial problems. The pasta used lasagne th n i a tend becomo st e ver onls y softsmalywa a t agai t i bu , s ln a portio totae th lf no dish it has been acceptable.

Sliced beans, diced carrots, diced onions and sliced mushrooms have been used in the chicken and vegetable stew. The onions were sauteed in a little oil after which the mushrooms, precooked chicke d spicean n s were added. This mixtur s cookewa er fo d approximatel hou tiltiny1 a n ri g frying pan. Commercially blanched frozen carrot beand san s were then added together with the thickeners and the whole mixture was simmered for about minutes5 vegetablee Th . s tende becomo dt e reasonably soft after processin t wergbu e still

24 acceptable in the total dish. Seasonal variation in the beans caused certain problems, because e beanith f s were slightl d theol yy tende becomo dt e gre coloun i y d stringan r y after processing.

tomate Th oniod oan n sauce usenumbea n di f disheo r prepares swa d using chopped onions, tinned peeled tomatoes and a variety of herbs and spices. Because this is already a mush t yaffecte processe no produc th s y db wa t .i t

The commercially processed items themselves posed certain problems. It was found that althoug smokee hth d chickens were supposet smokeho e commerciae b dth o dt l smokerd sdi not control their process effectively and, therefore, the chickens were undercooked in the centre produce Th .initialls wa t y perfectly acceptable t afte bu ,perioa r f aboudo month9 t s storage began to deteriorate physically due to inadequate inhibition of the enzymes. The meat became very soft and had a slightly soapy feel if rubbed between the fingers. Production of this specific produc ceases commerciae ha tth s da l smokers cannot guarante esufficientla y "cooked" chicken. The smoked viennas also tended to become soft after a few months and althoug produce hth thes i t n perfectly acceptabl bees ha nt e i discontinued .

The specific formulation of the country sausage that was bought was acceptable, but usee coulb Koshen t di dno r recipes (2.4) This produc initialls twa y acceptabl developet ebu d a very bitter taste after about 12 months. This again proved that the specific formulation that was use combinatioe wels th da s a l f herbn o spice d san irradiaten si d precooked dishes swa of the utmost importance. Unfortunately therefore, recipe development has been a time consuming process, because quite often adverse effects were picke onlp du y after abouo t 9 t 12 month productiof so storaged nan .

thickenee Th rdishee useth n di s develope thermallCSIa e s th Ry wa d b y stable starch based thickener called "col-flo". Thi mosse proveth te b stabl numbeo da t f eo thickenerf ro s tested, but was still pretty much unstable. Depending on the different products, sauces become either very thin (the beef stroganoff sauce becomes totally watery gel-likr )o e th n e(i beee casth ff eo stew ) afte processe th r worn I . k don Louy eb w (1991discoveres wa t )i d that producte th f o .H p Sauce e th considerethie o partlar s t si e ydu morn di e detail elsewhere.

Mutton processing was also attempted, but somehow its specific type of fat or other components lead to products with a very rancid taste and smell and after several futile attempts using different recipes and methods of cooking, it was decided to drop this line of research.

Veniso ostricd nan h meat have both been tested t bot exceptionalle bu ,h ar d an y ydr tasteless due to the very low fat found in the muscle itself. These meats can be used very effectively in casserole type dishes or in a sauce, but due to the relative cost and availability of the meat, the products were not investigated further.

3.2. Fish Some work has been carried out on prepared shelf stable fish, but with very little success mainle .du yellow-brow a This o yt wa s n colour thaproducte th t s developed after processing as well as a total loss of texture, which resulted in a mushy product. Several different types of fish were studied, e.g. "dry" meat fish like hake, "oily" meat fish like tuna, as well as finely textured and coarsely textured fish. In addition, fish dishes like fish with white sauce, fish pie and fish bobotie were tried, but sensorially, none of these were acceptable.

25 3.3. Starches and vegetables

3.3.1. Vegetables

The Brassica type vegetables were totally unsuccessful mostly because of a very strong irradiation smel tastd s welan la e s ver a l y dark discolouring. Those tested were spinach, broccol cauliflowerd an i spinace Th .cauliflowed han almosn ra alsd otha pinke th cas o t t stalks.

Celery, radishes, leeks, garlic, green peppers, red peppers, bean sprouts, parsnips, turnips, asparagus, vegetable marrows, gem squashes and cucumbers were all not acceptable tasted ba ,o eithe t smel e unacceptablr du ro l e colou texturd combinatioa an r r eo f thesno e defects. Aubergines and mushrooms became very limp, turned black and had an unacceptable flavou odourd an r . However mushroome th , s were acceptabl dishen ei s like beef stroganoff stir-friee th an n di d rice dishes. Pumpkin became gritty wit hdara k oranges colouwa d an r t acceptablno e overall. Potatoes becam pink/browea n taste texturd colouth ean s d ean wa r totally unacceptable.

Sweetcorn was acceptable although slightly gritty directly after processing, but as time progressed, develope a verd y bitter almost burnt type taste which mad e producth e t unacceptable about 9-12 months after processing. Likewis mixee eth d vegetables, consisting of diced carrots, peas, bean sweetcord san n were also unacceptable afte month2 1 r s because of the taste.

onione Th s became very limp wert bu , e acceptabl tastn smelld eo ean . Carrots became a dark dull orange colour, slightly limp but still acceptable according to taste and smell. Cabbage and red cabbage became very soft, but were acceptable on smell and taste although coloue th r became dull. Beetroo tomatd an t o became softt stilbu l, acceptable. Peas became softer, appeared duller, but were acceptable. Runner beans became grey-green and stringy, but if young beans were used, were still acceptable.

In general it was found that the quality of the vegetables was very inconsistent if the initial raw material was bought at the local fresh produce market. The blanching could not controllee b d effectivel kitchee commerciallo s th d n i yn an y blanched frozen products were employed. These vegetables were the year2 ne suseth r thadfo t shelf stable vegetables were supplied on a commercial basis to the SADF. The products supplied were peas, baby carrots, baby carrots with peas, tomat oniod oan n mix, cabbage (thiboughs swa t fres cooked han d partially), mixed vegetables and sweetcorn. It was also found that during the process all vegetables lost considerable moistur pouree eb beforwhico f t dof d hha e serving.

3.5.2. Starches

paste rice welTh s th ea a s appearea l d light yellowis colourn hi . This colour intensified over tune. The pasta had an "oily"- shiny appearance. The rice lost a lot of moisture during e procesth d liquian s d could physicall e e packethigheth th t f e poureo b A ry. t ou d temperatures (7° -7°Cd Cproduce an distincth )a d ha t t irradiatioe n th smel t tastea d t an l bu , lower temperatures were acceptable with respect to taste and smell. The pasta was very soft and mushy after irradiation and the texture of the rice was gritty. It was decided that none of these were very successful products. After being approache customee th y db r e somth f eo starch wor repeateds kwa starchee Th . s that were considered included rice, maize porridge, kidney beans, sweet potatoes and wheat.

26 The rice was initially partially cooked and then processed further, but it was found that it became yellowish, gritty, mushy and lost a lot of moisture. In an attempt to counter this problem the rice was first fried in heated oil for a few minutes and then partially cooked, which led to a slightly finer product but over time it still lost a lot of moisture. It was found tha rinsiny b t g excess rice producstarce th eth f hof t improved t onlbu ,y marginally.

Yellow s preparericwa e addiny b d g tumeri raisind e friepartialld an cth an do t s y cooked ricthed ean n packe processedd dan yelloe Th . w colour fro tumerie e mth th d chi colour formed by the process, but the other problems as mentioned above were still relèvent.

A stir fried rice dish and savoury rice dishes (both white and yellow) where the rice was cooked as above with blanched vegetables (diced carrots, peas) and cooked vegetables (onions, mushrooms, and bean sprouts) and spices were also tried. Here it was found that the colour change in the white rice was masked, but the texture of the rice was still mushy. vegetablee Th s became lim duld coloupn an i l r afte procesoverale e th th r d lsan appearance of the product was not very appetizing. The bean sprouts were later removed from the product list because of excessive limpness.

Wheat was partially cooked, but this also led to a slightly gritty type product. It was usestir-fra n di mentiones ya d contrase aboveth t bu , t betwee slightle nth y gritty firm wheat vere th yd liman p vegetable t acceptableno s swa .

e kidneTh y beans wer hours3 e o t cooke ,2 washer dfo d with cold wate thed an rn chilled and processed. The beans were slightly gritty but were the most acceptable of all the different starches tested. They also did not lose moisture during the process. Problems were experienced in obtaining large quantities of dried beans of a consistent quality and size. At stage on e beans could onl obtainee yb d that appeared slightly green after processin wherr go e the veins in the skin of the beans turned black. This product was therefore not acceptable becaus producw ra qualite e eth th t guaranteede coulf b yo t dno .

The maize meal porridge was extremely slushy after processing and lost its total consistency. Here, as with the sweetcorn, a burnt taste developed. It was subsequently found thafreezine th t g broke dow structure nth porridge th f eo e and, after freezing, water could be forced out of the porridge by pressing a ball of it in the hand. Because of the problems with freezing this product was not investigated further.

Blanched sliced, frozen sweet potatoes were packed, froze irradiatedd nan t aftebu , r processing the product was totally mushy and unacceptable.

3.4. Ethnic meals s beeAha s n discussed earlier, althoug meae poultrd hth an t y dishe beed ha sn very successful, the starch and vegetable processing was less acceptable. As a result these components of Kosher meals were re-evaluated.

Members of the Catering Corp of the Army tasted these and decided that, within the context of the provision, they were acceptable. At this stage only 6 months worth of data were available. Where accepted, these starche vegetabled an s s wit initian ha l shelf-liff o e onl monthy6 s were tried, wit understandine hth g tha extension a t increaso n t year 2 o t st ei would be the target. After the first year it was found that vegetables and starches could be guaranteed for 9 months, after which they became sensorially unacceptable mostly due to texture defects.

27 productioe Th f shelno f stable meat dishes wit hshelf-lifa year2 vegetablef d o esan s wit hshelf-lifa month6 f followss beguno es a s lise swa wa tTh .:

Meat Dishes Starches Vegetables

Meat loaf Stir-fry rice Peas Smoked viennas Maize meal porridge Tomat onioo& x nmi Roast chicken Sweet potatoes Baby carrots Country sausage Kidney beans Baby carrots & peas Beef curry Yellow rice Cabbage Chicken and tomato White rice Mixed vegetables Chicken casserole Savoury white rice Sweetcorn Bobotie Stir-fry wheat

Beef steak in gravy Savoury yellow rice Chicken stew Smoked chicken Beorewors Steak Meat balls Chicken curry Beef stew Roast beef Hamburgers

Sinc shelf-life e th variou e th f eo s items differed decides paco t wa t t i kfula ,d no l meal in a compartmentalised mealtray, but to pack the menu items separately in the flexible vacuum pouches described in (2.1). Items of varying age could then be used simultaneously.

3.5. Sauces

resultw Dependinne e s th obtaine n o g y Louwb d , vegetable dishes that neea d thickening agent can again be investigated. At the tune that further vegetable work ceased, the lack of stable thickener was the major problem to the development of shelf stable vegetable dishes. Once a stable thickener is available this work can be continued.

. DISCUSSIO4 CONCLUSIOND NAN S

4.1 Meat and poultry components

producte th l Al s hav1 liste3. en d i bee semi-commerciaa n o produce C AE y db l basis years8 o lase t fo th .7 r t These were supplie SADe th outdoo d o dt Fan r enthusiasta n o s special permit provided by the South African Department of Health and Population Development. Semi-continuous optimization of the recipes has taken place throughout this time supple Th . f thesyo e product availabls si ordern eo .

4.2. Fish

No progress has been made hi developing components in this area although successful processing of shellfish (shrimp) has been reported elsewhere.

28 4.3. Starche vegetabled san s

4.3.1. Vegetables

e resultTh s were disappointin d moran g e mus e donb t o consolidatt e e vegetable processing other tha inclusions na mean si t dishes suc stewss ha .

4.3.2. Starches

Irradiated starch based products wer successfult eno Koshee th f I . r beet projecno nd ha t terminate starchee dth s would have been refused withi monthsfirse w nth fe t . This aref ao work needs a major review.

4.4. Ethnic meals

supplo t Whe s Arm0 e Koshee th y30 wa n th d t yi an r C contracAE signes e th wa t y db men with 3 meals per day for 3 years. This figure was derived from the number of registered Jews in the Army at that time. For the first year AEC supplied Kosher food in these quantities. During the second year of the contract, the troops had by now become aware of this syste mseno t d the t wherevemou r required and, therefore ,f the o onl mx ysi registere d as "Kosher" Jews. AEC were, therefore producing far too much Kosher food. Hence the wor programmd kan f developmeneo discontinueds wa t .

4.5. Sauces

Wor stils ki lLouwy undeb y interi o t CSIn a 1 wa r t Rmbu result availablee sar .

5. SUMMARY

meae Th t products have bee exceptionallf no y high qualit good yan d tast textured ean , although optimization of some of the sauces is still required. Any research work in the field of the meat dishes would therefore concentrate on recipe formulation, optimization and selection of thickeners used.

It is possible to produce some shelf-stable vegetables, but on the whole they are not very appetizin appearancn gi fairle ar tastd yd ean processe expensivean th s o i t t e I . edu therefore possibl canney bu o et d vegetable equivalenf so better o t r qualit t roughlya ythira d of the price. However, vegetable dishes could possibly be investigated, since being value added products the price is not such a problem.

summaryn I , kidneexcepe th r yfo t beans ,starche e nonth f eo s tested were acceptable, mostly becaus damage th f eo e freezine subsequen e donth th y d eb gan t moisturef o loss l Al . them wer e procese t palatabl ediblth cose no f packaginth d t o t d san ebu ean agais gwa na major stumbling block in contrast with the meat where the raw product is already a much higher priced commodit thereforn ca d yan e absor procese bth s costs.

'Louw . (1991)C , (Honsc BS . ) Food Science Project, Universit Pretoriaf yo , Pretoria, South Africa.

29 Finally numbea , successfuf ro l interesteproducty b e us available r sar d fo partiesw eno . Some components need refinemen otherd an t majosa r research initiative directioe Th . d nan scop f woreo k wil dictatee b l customey db r need investmend san t available.

ACKNOWLEDGEMENTS

e essencTh f thieo s contributio derives i n d fro mrepora t prepare Ingrie y d b . dN Bruyn of Biogam, Atomic Energy Corporation of South Africa, in collaboration with this author.

30 Appendix C

PROCES PRODUCINF SO G SHELF-STABLE, IRRADIATED FOODS productioe stepy th ke n si e Th thesf no efollowinge itemth e sar :

. 1 Precoo meatw kra , poultr seafood an y d itema "mediu o t s m done" state (internal temperatur approximatelf eo y 75°C inactivato )t e degradative tissue enzymes unlese sth ite mnormalls i y thermally processed before-hand (e.g. hot-smoked ham, corned beef, pastrami).

2. Hermetically vacuum seal in individual multi-layer aluminum foil barrier pouches, such as developed by the US Army programme and approved by the US Food and Drug Administration (PDA), or equivalent.

3. Cryogenically or mechanically freeze the pouches of product to around -40°C and irradiate e hard-frozewhilth n ei n stat maintaio et n eating/nutritional quality. Over- laying packages/carton effectivn a s i inexpensivd e an se ic f mainwit o y y hdr -wa e taining the hard frozen state during lengthy gamma irradiation

irradiation y r gammra Fo X r ao , pack individual frozen pouche shippinn si g cartond san frozen-store or keep under dry ice prior to irradiation. For irradiation times in excess of an hour a layer of dry ice should be placed over and around each carton to maintain hare th d frozen state during irradiation. maximue Eveth t na m energMeV0 1 f ,yo electron beam irradiation penetration (whicw lo s hha ) mus appliee tb eaco dt h individual frozen pouch r examplefo ; , pouches lyin ga bel flan to tcarryin g them undee th r electron beam. Pouches thicker than a few centimeters should be irradiated on each side (two-pass f totao l% minimu50 , m dos eaco et h pass r uniformityfo ) . Electron beam irradiation dose rate normalle st ar requir no higo o t ys e s ha activ e maintenance th f eo frozen state during irradiation (i.e exposure .th e tim normalls ei brieo yto alloo t f w significant warming).

4. Irradiate to the prescribed minimum dose (ca. 25-45 kGy depending on the product) provido t a e10~ 12 leve f anti-botulinuo l m sterility assurance employing appropriate dosimetry. Required minimum dose r varioufo s s products have been determiney db C. botulinum inoculated pack studies don eS Arm U unde e y th rprogramm e (see Microbiological Safety section). At these minimum dose levels the products are microbiologically sterile and can be stored for years under any ambient conditions since endogenous enzymes that would degrade the products over time in the absence of viable microorganisms have been heat-inactivated prior to packaging and irradiation.

5. Immediately following irradiation allow the product(s) to warm up to ambient temperature. Pack individually electron-irradiated pouche shippinn si g cartons wits a , h gamma and X ray irradiated pouches before irradiation of the filled cartons.

31 REFERENCES

[I] Anellis, A., D. Berkowitz, C. Jarboe, and H.M. El-Bisi. 1969. Radiation sterilization of prototype military foods. III. Pork loin. Appl. Microbiol. 604-611. [2] Anellis, A., D. Berkowitz, C. Jarboe, and H.M. El-Bisi. 1967. Radiation sterilization of prototype military foods. II. Cured ham. Appl. Microbiol. 15:166-177. [3] Anellis, A., D. Berkowitz, W. Swantak, and C. Strojan. 1972. Radiation sterilization of prototype military foods: Low-temperature irradiation of codfish cake, corned beef, and pork sausage. Appl. Microbiol. 24:453-462. [4] Anellis, A., N. Gréez, D.A. Huber, D. Berkowitz, M.D. Schneider, and M. Simon. 1965. Radiation sterilization of bacon for military feeding. Appl. Microbiol. 13:37-42. [5] Anellis, A., D.B. Rowley, and E.W. Ross. 1979. Microbiological safety of radappert- ized beef. J. Food Protect. 42:927-932. [6] Anellis, A., E. Shattuck, T. Latt, S. Songpasertchal, D.B. Rowley, and E.W. Ross, Jr. 1977a. Gamma irradiation at -30 + 10 degrees of low level nitrite/nitrate ham. Spore Research 2:631-647. [7] Anellis, A., E. Shattuck, M. Morin, B. Srisara, S. Qvale, D. B. Rowley, and E. W. Ross . 1977bJr , . Cryogenic gamma irradiatio f prototypno e porchicked kan d nan antagonistic effect between Clostridium botulinum . ApplB d type. an EnvironA s . Microbiol. 34:823-831. . Shattuck E ] Anellis, . Rowley[8 B . E. Ross . , W D ,. A. ,, E , Whaley. R ,. D.N.V d an , Dowell . 1975Jr , . Low-temperature irradiatio beef methodnd o an f evaluatior sfo f no a radappertization process. Appl. Microbiol. 30:811-820. [9] Drake, S. D., J. B. Evans, and C. F. Niven. 1958. Microbial flora of packaged frankfurters and their radiation resistance. Food Res. 23:291-296. [10] El-Bisi . 1966M . H ,. Radiation death kinetic . botulinuCl f so m spore t cryogenia s c temperatures . 89-107pp , . INM. . Robert A Ingra . T d sm (ed.an ) Botulism 1966, Proc. Inth 5t . Symp. Food Microbiol., Moscow, Chapma Halld nan , Ltd., London. [II] Erdman , andBM. . Watts. M .A , . 1957. Radiation preservatio curef no d meats. Food Technol. 11:349-353. [12 . Walker]A . Grecz A . Anellis . Berkowitz, A ,D N. , d an , . 1971. Effec f irradiatioo t n temperature in the range -196 to 95C on the resistance of spores of Clostridium botulinum cooken i A d33 beef. Can . MicrobiolJ . . 17:135-142. [13] Greenberg, R. A., B. O. Bladel, and W. J. Zingelmann. 1965. Radiation injury of Clostridium botulinum spores in cured meat. Appl. Microbiol. 13:743-748. [14] Huhtanen, C. N., R. K. Jenkins, and D. W. Thayer. 1989. Gamma radiation sensitivity of Listeria monocytogenes. . FooJ d Prot. 52:610-613. [15 ]. Maxcy B Lambert . R , . 1984D. . ,J . Effec gamf o t a radiatio Campylobacterjejuni.n no J. Food Sei. 49:665-667, 674. . . [16JenkinsThayer K . W BuchananL ] . . . R PalumboD R , . d A. 1986an ,. S , . Determination of irradiation D-Values for Aeromonas hydrophila. J. Food Prot. 49:189- 191. [17] Pratt, G.B O.Pd an . . Ecklund. 1956. Organoleptic studie f irradiateso d foods. Food Technol. 10:496-499. [18] Thayer, D. W., and G. Boyd. 1992. Gamma ray processing to destroy Staphylococcus aureus mechanicalln i y deboned chicken meat . FooJ . d Sei. 57:848-851. [19] Thayer, D.W., and G. Boyd. 1993. Elimination of Escherichia coli O157:H7 in meats by gamma irradiation. Appl. Environ. Microbiol. 59:1030-1034. [20] Thayer, D.W. . BoydG , , W.S. Mueller, C.A. Lipson . HayneC . S.Hd W , an , . Baer. 1990. Radiation resistance of Salmonella. J. Indust. Microbiol. 5:383-390.

32 [21] . HeiligmanWierbickiF d an . E ,. 1973. Shelf stable curewitm ha hd low-nitrate additions preserved by radappertization. Proc. Inti. Symp. Nitrite Meat Prod., Zeist, PUDOC, Wageningen. 189-212. [22] Wierbicki, E.F. Heiligman A.Ed an , . Wasserman. 1976. Irradiatio conceivabla s na e wa f reducinyo g nitrite curen i s d meats. Proc Intld 2n .. Symp. Nitrite Meat Prod., Zeist, Wageningen. 75-81.

33 LIS PARTICIPANTF TO S

Ahmed, M. Food Preservation Section, International Atomic Energy Agency, Wagramerstrass , 100P.Ox e5 Bo ,. A-1400 Vienna, Austria

Giddings, G.G. Beec1 6 h Road, Randolph, New Jersey 07869, United State f Americso a

Gould, G.W. Unilever Research Colworth Laboratory, Colworth House, Sharnbrook, Bedford MK44 1LQ, United Kingdom

Kaiman. B , AGROSTER Irradiator Company, Jâszberényi ût 5, H-1106 Budapest, Hungary

Ladomery, L.G. Food Preservation Section, International Atomic Energy Agency, Wagramerstrasse 5, P.O. Box 100, A-1400 Vienna, Austria

Loaharanu. P , Food Preservation Section, International Atomic Energy Agency, Wagramerstrass 100, P.Ox e5 ,Bo . A-1400 Vienna, Austria

McGill, A.G. (Rapporteur) Colleg f Foo eo Agricultured dan , Plymouth, United Kingdom

Thayer (Chairman)D. , Food Safety, USDA/ARS, North Atlantic Area, Eastern Regional Research Center, Eas0 60 t Mermaid Lane, Philadelphia, Pennsylvania 19118, United State f Americso a

en nCM o in en

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