Project no.: 243452Project acronym: MusselsAliveProject title:Development of best practice and new technology for grading,...
Report no.Deliverable 4.1 - Report on Best Practice Handling and Transportation of Live MusselsProject TitleMussels Alive ...
Table of contents 1. Problem definition 6 2. Introduction to mussels 7 3. Transport of live mussels 9o Scotland 11o Nor...
MusselsAliveD 4.14BackgroundThe Deliverable 4.1 Report on Best Practice Handling and Transportation ofLive Mussels, is an ...
MusselsAliveD 4.15GlossaryHarvestedShellfish harvested on the same day and from the same area (if classification isnecessa...
MusselsAliveD 4.161. Problem definitionTransporting live musselsBivalve species like oysters, mussels, manilaand hard shel...
MusselsAliveD 4.172. Introduction to musselsLife in seawaterMussels are invertebrate molluscs includingfamiliar forms such...
MusselsAliveD 4.18Blue Mussel Quick Fact SheetDistributionOccurs from the White Sea, south to southern France in the N.E. ...
MusselsAliveD 4.193.Transport of live musselsThe industry perspective: Scotland, Ireland and NorwayThe trade chain is diff...
MusselsAliveD 4.110Table 1 Summary of the transport units and vehicle used by the different companies in Scotland, Norway ...
MusselsAliveD 4.111Systems in use: ScotlandThe questionnaires were completed throughpersonal interviews made during the As...
MusselsAliveD 4.112Systems in use: NorwayThe questionnaires were completed throughperson to person and phone interviews ma...
MusselsAliveD 4.113Systems in use: Norway (cont.)One solution to this problem is to keepoperators and clients well informe...
MusselsAliveD 4.114Systems in use: IrelandFour Irish companies participated in thisquestionnaire, 3 companies sent theques...
MusselsAliveD 4.115Transport of live musselsThe industry perspective: systems in use worldwideSpainAurelio Silva Abalo, S....
MusselsAliveD 4.116Systems in use worldwideAustraliaKinkawooka Shellfish is an owner-operatedcompany located in Port Linco...
MusselsAliveD 4.117Systems in use worldwideCanadaWhereas in Australia and in NewZealand the bag system is used totransport...
MusselsAliveD 4.118Systems in use worldwide - slurry ice technologyThe slurry ice technologyWhether mussels come from Aust...
MusselsAliveD 4.119Systems in use worldwide: the slurry ice technologyThe Prince Edward Aqua Farms process is asfollows:Af...
MusselsAliveD 4.120Transport of live musselsThe science perspectiveThere are four possible storage conditions forlive muss...
MusselsAliveD 4.121Adding ice to mussels during harvesting effectively chills the product quickly.Also, holding mussels un...
MusselsAliveD 4.1224. MusselsAlive TrialSwansea UniversityIn March 2011 mussels were sampled toassess their general condit...
MusselsAliveD 4.123MusselsAlive TrialAfter 22 h transport mussels were sampled once again at Swansea University, then bags...
MusselsAliveD 4.124MusselsAlive TrialResultsThis experiment has two elements. The firstprovides a comparison of the conseq...
MusselsAliveD 4.125MusselsAlive TrialFigure 15 Temperature during different transport conditions. Blue line indicates temp...
MusselsAliveD 4.1261212372601234567Ice&Lid Ice No Lid No Ice Lid No ice&No LidMortality(%)Depurated Non DepuratedMusselsAl...
MusselsAliveD 4.127MusselsAlive Trial2.3. Weight lossIt is general knowledge that during transportout of the water mussels...
MusselsAliveD 4.128MusselsAlive Trial2.4 Serum AmmoniaMeasurements of ammonia in blood serumprovide a rapid, quantitative ...
MusselsAliveD 4.129MusselsAlive TrialPrevious studies reported that a 24h re-immersion process of the mussels followingany...
MusselsAliveD 4.1305.Regulations and recommendationsA) 853/2004, Annex III, Section VII, Chap II, B2B) 853/2004, Annex III...
MusselsAliveD 4.1316. References1. Mayes, A.S. and D.I. Fraser, Scottish Shellfish Farm Production Survey. 2011: Edinburgh...
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Development of best practice and new technology for grading, handling, transportation, conditioning and storage of mussels for SMEs in the European mussel industry

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The Deliverable 4.1 Report on Best Practice Handling and Transportation of Live Mussels, is an overview of the existing knowledge of the trade chains of mussels produced in Scotland, Ireland and Norway and provides a detailed description of best practice for handling and transportation of blue mussels. This protocol was tailored to participating SME AGs and SMEs. The methodology used to collect the information for this report was based on available literature, data collected from WP1 and also from personal and phone call interviews to traders of mussels in Scotland, Ireland and Norway.

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Development of best practice and new technology for grading, handling, transportation, conditioning and storage of mussels for SMEs in the European mussel industry

  1. 1. Project no.: 243452Project acronym: MusselsAliveProject title:Development of best practice and new technology for grading, handling, transportation,conditioning and storage of mussels for SMEs in the European mussel industryResearch for the benefit of SMEsDeliverable 4.1 Report on Best Practice Handling and Transportation of LiveMusselsDue date of deliverable: Month 17Actual submission date: Month 20Start date of project: 01.06.2010 Duration: 36 monthsOrganisation name of lead contractor for this deliverable: Swansea University, UKReport status: FinalProject co-funded by the European Commission within the Seventh Framework Programme (2007-2013)Dissemination LevelPU Public XPP Restricted to other programme participants (including the Commission Services)RE Restricted to a group specified by the consortium (including the Commission Services)CO Confidential, only for members of the consortium (including the Commission Services)
  2. 2. Report no.Deliverable 4.1 - Report on Best Practice Handling and Transportation of Live MusselsProject TitleMussels Alive - Development of best practice and new technology for grading, handling,transportation, conditioning and storage of mussels for SMEs in the European mussel industryPrepared by (SU):Sara BarrentoIngrid LupatschAlex Keay
  3. 3. Table of contents 1. Problem definition 6 2. Introduction to mussels 7 3. Transport of live mussels 9o Scotland 11o Norway 12o Ireland 14o Systems in use world wide 15o The science perspective 20 4. Mussels Alive - Simulated transport 22 5. Regulations and recommendations 30 6. References 31
  4. 4. MusselsAliveD 4.14BackgroundThe Deliverable 4.1 Report on Best Practice Handling and Transportation ofLive Mussels, is an overview of the existing knowledge of the trade chainsof mussels produced in Scotland, Ireland and Norway and provides adetailed description of best practice for handling and transportation of bluemussels. This protocol was tailored to participating SME AGs and SMEs.The methodology used to collect the information for this report was basedon available literature, data collected from WP1 and also from personal andphone call interviews to traders of mussels in Scotland, Ireland and Norway.
  5. 5. MusselsAliveD 4.15GlossaryHarvestedShellfish harvested on the same day and from the same area (if classification isnecessary, of the same class).Batch – Depurated.Shellfish that have been depurated through the same cycle of the same depurationsystemBivalve molluscsAny marine or freshwater molluscs of the class Pelecypoda (formerly bivalvia orLamellibranchia), having a laterally compressed body, a shell consisting of two hingedvalves, and gills for respiration. The group includes, among others, clams, cockles,oysters and mussels.Classification ofbivalve molluscharvesting areasA system for grading harvesting areas based on levels of bacterial indicator organismsin the surrounding seawater (using faecal coliforms in the US) or the shellfishthemselves (using Escherichia coli within the EU).Clean seawaterSeawater from any source where harmful microbiological contamination, substancesand/or toxic plankton are not present in such quantities as may adversely affect thehealth quality of bivalve molluscs or to impair their tasteColiformGram negative, facultatively anaerobic rod-shaped bacteria which ferment lactose toproduce acid and gas at 37 °C. Members of this group normally inhabit the intestineof warm-blooded animals but may also be found in the environment (e.g. on plantmaterial and soil).ConditioningThe storage of live bivalve molluscs, whose quality does not indicate the need forrelaying or treatment in a purification plant, in tanks or any other installationcontaining clean sea water or in natural sites to remove sand, mud or slime andimprove product acceptabilityDepuration cycleThe depuration process from the point at which the shellfish are immersed in theseawater and all of the conditions for depuration process are in the correct rangeuntil the time when depuration is ended, e.g. by draining the tanks. If conditions goout of range then the cycle must be identified as starting again for the purposes ofthe depuration period.Depuration centre Any approved establishment for the depuration of live bivalve molluscsEscherichia coliA species of bacterium specifically associated with the intestines of warm-bloodedanimals and birdsHeat shockingThe process of subjecting bivalve molluscs in the shell to any form of heat treatment,such as steam, hot water, or dry heat for a short period of time, to facilitate rapidremoval of meat from the shell for the purpose of shuckingRelay areaAny sea, estuarine or lagoon area with boundaries clearly marked and indicated bybuoys, posts or any other fixed means, and used exclusively for the naturalpurification of live bivalve molluscs.RelayingThe removal of bivalve molluscs from microbiologically contaminated growing areato an acceptable growing or holding area under the supervision of the agency havingjurisdiction and holding them there for the time necessary for the reduction ofcontamination to an acceptable level for human consumption (Codex AlimentariusCode of Practice).
  6. 6. MusselsAliveD 4.161. Problem definitionTransporting live musselsBivalve species like oysters, mussels, manilaand hard shell clams can survive for extendedperiods out of water and can be traded forhuman consumption as live animals.The primary aim of capturing, holding andtransporting live mussels is to deliver them tomarket in the best possible condition. Musselswill be exposed to some level of stress duringall or part of the trade chain.Stress can be defined as any factor (eitherexternal or internal) causing a physiologicaldisturbance to the mussels. In the live musselindustry these factors include capture, de-clumping, fluctuating temperatures, sunlightand other bright lights, wind or drafts, handlingand physical damage, poor water qualityduring holding, conditioning and purification.Mussels are generally able to recover fromsuch stresses, however if any or a combinationof those stresses are sufficiently intense, thenpoor quality (broken shells, gaping, unpleasantsmell) or dead mussels will result. Thus,transport systems need to ensure mussels areheld in conditions that keep stress to aminimum.The design of transport systems is governed bya number of factors, with economics being amajor driving factor. Systems also need to bepractical to use and manage, and designed tosuit the biological requirements of the animal.For mussels there is now a range of biologicalinformation that can be practically used in thedesign of transport systems. How theinformation is adopted will depend on theharvesting origin of mussels (cold water,temperate waters), transport duration andreception infrastructures.This guide provides information to the musselindustry on transport of live mussels, focussingon the physiological requirements of musselsand methods of ensuring optimal conditions.Further experiments to optimize the besttransport and recovery temperatures might beneeded. Operators must be aware that for thesame problem different solutions can arise anddifferent procedures might be neededthroughout the year according to temperaturechanges. Traceability and a narrower tradechain would also assist the technicalprocedures required to achieve a bettertransport and standardized handling andtransport practices.
  7. 7. MusselsAliveD 4.172. Introduction to musselsLife in seawaterMussels are invertebrate molluscs includingfamiliar forms such as clams, oysters, squids,octopus and snails. Mussels dominate theintertidal region (Figure 1) in temperate seas ofthe northern and southern hemispheres; theycan form extensive beds dominating the rocksurface, strips or patches. Mussels living in theintertidal zone must be able to surviveexposure to the air (desiccation), abrasionaction of waves and ice, discontinuousavailability of food, large fluctuations intemperature, and sometimes exposure tofresh water from the rain and seepinggroundwater. Competition and predation bystarfish, dog whelks, shore crabs and variousbirds are also factors important in determiningits distribution. Starvation is also a risk whenthe tide is out, since most intertidal animalsfeed only when they are submerged. Thelength of time that organisms are exposed tothe air depends on the local tidal range and onwhere on the shore they are located. On theother hand mussels cultured in long lines andrafts are submerged continuously and do notface the same challenges.Figure 1. Intertidal zone.Animals have evolved different strategies to cope with challenges of life according to their habitats; Musselsthat live in the intertidal zone have increased thermal resistance, reduced evaporation when exposed to airas they normally are trained to close their valves and thus exhibit a longer shelf-life than those that aresubmerged continuously.
  8. 8. MusselsAliveD 4.18Blue Mussel Quick Fact SheetDistributionOccurs from the White Sea, south to southern France in the N.E. Atlantic. Inthe W. Atlantic it extends from the Canadian Maritimes south to NorthCarolina. It occurs on the coasts of Chile, Argentina, the Falkland Islands andthe Kerguelen Isles.Habitat PreferencesPhysiographic preferences Open coast Strait / sound Sea loch Ria / Voe Estuary Enclosed coast /EmbaymentBiological zone preferences Lower Eulittoral Mid Eulittoral Sublittoral Fringe Upper Eulittoral Upper InfralittoralSubstratum / habitatpreferences Artificial (e.g. metal,wood, concrete) Bedrock Biogenic reef Caves Crevices / fissures Large to very largeboulders Mixed Muddy gravel Muddy sand Rockpools Sandy mud Smallboulders UnderbouldersTidal strength preferences Moderately Strong (1-3 kn) Strong (3-6 kn) Weak (<1 kn)Wave exposure preferences Exposed Moderately Exposed Sheltered Very Exposed Very ShelteredSalinity preferences Full (30-40 ‰) Reduced (18-30 ‰) Variable (18-40 ‰)Temperature preferences  From 0 to 20 COxygen preferences  Above 60 %Preferred particleconcentration 50x103to > 800x103cells/mLParticle size  > 2 m to 100 mLight preferences  Mussels are more active during the nightDepth range  Intertidal to approximately 5mReproductionReproductive type  Having separate sexesReproductive frequency  Breeds every year over an extended or drawn out periodAge at maturity  1 to 2 yearsGeneration time  1 to 2 yearsFecundity (no. of eggs)  >1,000,000 up to 20,000,000Time of first gamete  AprilTime of last gamete  SeptemberLarval settling time  1 to 6 months
  9. 9. MusselsAliveD 4.193.Transport of live musselsThe industry perspective: Scotland, Ireland and NorwayThe trade chain is different in Norway, Scotlandand Ireland. To have a better understanding ofthe different aspects of the three countries,questionnaires were developed anddisseminated in these three countries. Transportoccurs at different stages of the trade chain. Thefollowing diagram is a brief summary of thetrade chain which has already been approachedin previous deliverables and illustrates wheretransport takes place during the trade of livemussels. The short distance transportcorresponds to transfers that take place in amatter of few minutes, for instance from theharvesting site to the barge, or to the shorewhere the dispatch or depuration centres areusually located.Whereas the medium to long distance transportcorresponds to transfers that can take a fewhours to up to 3 days. In total 6 Scottishcompanies, 3 Norwegian companies and 4 Irishcompanies participated in this questionnaire.One of the driving factors that makes transportand transport units different among companiesand in the same company is the clientrequirements (quantity; graded vs. non graded;mussels to be sold fresh or processed).To better understand the medium to longdistance transport process, the following tableshows a brief summary of transport units andtype of vehicles used by the three countries.Harvest(stripping,washing,de-clumping,grading)1.ShortdistancetransportBargeDispatchDepuration2.Mediumto longdistancetransportsFinalclientsDeliverable2.1. Deliverable3.1. Deliverable 4.1.Figure 2 Diagram summarizing the trade chain of live mussels and deliverables reports developed.
  10. 10. MusselsAliveD 4.110Table 1 Summary of the transport units and vehicle used by the different companies in Scotland, Norway andIreland; n – number of companies interviewed that use the transport unit or vehicle specified in each row.Scotland (n=6) Norway (n=4) Ireland (n=3)Transport Units n n n1 kg net 0 3 12 kg -10 kg net bags 0 0 2Cardbox 15 kg 1 0 020 to 25 kg bags, each with 4 or 5 nets (5 kgeach)2 0 0Box (25 kg) 1 0 0Bins (250-300kg) 3 0 0Bags (500-800 kg) 3 0 1VehicleLight good vehicle (closed chilled van at 4 C) 3 0 3Lorry chilled at 0-4 C 3 3 0Lorry chilled at 3-5C 0 0 3Details regarding each country are given in the following pages.
  11. 11. MusselsAliveD 4.111Systems in use: ScotlandThe questionnaires were completed throughpersonal interviews made during the Associationof Scottish Shellfish Growers annual meetingwhich took place in Oban between the 3rdand5thof October, 2011. The six companies thatparticipated in the questionnaire represent 25 %of the total production (tonnes/year) inScotland, (that is 7199 tonnes in 2010 [1]). Ingeneral companies with annual productionabove 150 tonnes, believe that ice is crucialduring transport.One of the companies specializes in providingmussels during the summer months as theyfound a market opportunity between April andOctober. During this season, live mussels have ahigh demand but it is also difficult to supply thelive market, as mussels are usually spawning orsites might be class B or even closed due tobiotoxins. This company supplies mussels torestaurants in the UK and to the ScottishShellfish Marketing Group (SSMG). According tothe manager of this company the crucial issue isto add ice as quick as possible either to 5 kg netbags, which are transported to restaurants inbins each with 50 bags (250 kg) covered with iceor to bulk bags (800 kg) that are transported tothe SSMG.The reasoning behind this practice, according tothe manager, is to prevent mussels from gaping.In the 800 kg bags bottom mussels cannot opendue to the weight anyway, but top mussels mustbe kept on ice.“Ice and keeping the cool chain is essential tokeep mussels alive especially during summermonths.”Another producer that depurates mussels alsomentioned that ice is essential. In this case afterdepuration, musselsare graded andpacked either in 5 kgnet bags or in 15 kgpolystyrene or cardboxes. The net bagsare usuallytransported in binseach containing 60net bags (300 kg total)and the ice is added inbetween the severallayers of bags. The 15 kg boxes are also iced.Mussel can also be exported to France usually in800 kg bags in Curtainsiders chilled at 4 C. Theduration of transport varies depending ondistance; transport to nearby restaurants cantake only 2 h but across the UK it can also takeup to 24 h. Mussels that are transferred to theSSMG take usually between 6 to 12 h, whereasexport to France can take up to 3 days.Table 2 Transport duration depending on the client. Inthe second column n means the total number ofcompanies that have a commercial relation with theclients stated in each row.In general mussel producers have no idea ofmortality after transport because there is nofeedback from the client. One of theinterviewees commented that farmers maynever realize that the system is not working justbecause they are not kept up to date.Client nTransportdurationScottish Shellfish MarketingGroup3 6 - 12 hRestaurants in UK 2 2 – 24 hFrance depuration/dispatchcentre3 3 daysFigure 3. Cardbox. Picturecourtesy of Sara Barrento.
  12. 12. MusselsAliveD 4.112Systems in use: NorwayThe questionnaires were completed throughperson to person and phone interviews madeduring August/September 2011, in Norway.The three companies that participated in thequestionnaire represent 74 % of the totalproduction (tonnes/year) in Norway, (that is1900 tonnes in 2008).All the three companies interviewed transportmussels in 1 kg net bags. Usually ten net bagsare placed in boxes with ice, in a proportion of2-3 kg of ice per box, (i.e. 10 kg of mussels).One company also mentioned that 1 kgmussels can be packed in modifiedatmosphere packaging (MAP), and 4-8 unitsare stacked in a card box. Usually mussels aretransported fromthe dispatchcentre to a centraldistributioncentre and thento wholesalersfollowed bysupermarketplatform andrestaurants. All three companies hire atransport company. Mussels are usuallytransported in lorries with closed rears thatcan carry a cargo between 12 to 24 tonnes.The air temperature is set to be between 0 to4C. In the following Table 3 is a summaryconcerning the transport to wholesalers.Table 3 Characterization of transport conditions in Norway, according to the location of the central distributioncentre.One of the companies managers mentionedthat smell related to transport is not relevantand does not occur, as long as the coolingsystem on the truck is working. If a smelloccurs it is most probably in modifiedatmosphere packed mussels. However anothermanager thinks that the smell in fresh musselscan occur and he suspects that it might also bedue to fouling organisms that apparently canpromote a sweet smell during transport.The Norwegian managers realize that keepingthe cool chain is the major critical point,especially during the summer months.Sometimes it is too hot in the lorry and the icein the 10 kg boxes melts. The temperatureregime upwards through the chain (operators,supermarket, etc.) is not well known. Therecan also be delays due to bad weather andaccidents, which again can compromise theuninterrupted cooling throughout the supplychain.Central distributioncentreTrondheim Oslo region Bergen MoscowAverage transport load 2.5 -4.9 tonnes 2 tonnes depends dependsTransport duration tothe destination2h 14h 38h 72hMortality after transport 0 < 1% 0 < 1% 0 % < 1%Presence of unpleasantsmell after transportNever Occasionally Occasionally NeverFigure 4. Net bags 1 kg. Picturecourtesy Snadder og Snaskum AS
  13. 13. MusselsAliveD 4.113Systems in use: Norway (cont.)One solution to this problem is to keepoperators and clients well informed and awareof the importance of temperature control. Inthis regard they understand that training is ofcrucial importance.Packaging was also pointed out as a crucialissue; mussels too fouled cannot be packed inmodified atmosphere, because they puncturethe package. One manager mentioned thatmussels spawn in the dispatch centre, this isvery common and it can happen daily for 2months or more (May, June, first half of July).Sometimes spawning occurs after packing,which is a problem in MAP. During this time ofthe year this company tries to induce spawningby double washing the mussels. In anothercompany they just discard spawning mussels.There is also some concern about what worksbest: a closed box or an open one, the bestratio of mussel to ice, and the amount ofmussels per box, considering the space, airavailable.
  14. 14. MusselsAliveD 4.114Systems in use: IrelandFour Irish companies participated in thisquestionnaire, 3 companies sent thequestionnaire by mail, and one wasinterviewed during the IFA aquaculture annualmeeting which took place on the 22ndofOctober, 2011 in Kinsale, Ireland.Two of the interviewed companies arerelatively small with an annual productionbetween 45 and 100 tonnes, and one only sells20 or 25 % of their total production (50 to 100tonnes) as fresh product. These companiesonly supply the internal market, mainly Irishrestaurants. In this case the mussels aredirectly transported from the dispatch centreto the restaurants, which last between 3 to 5hours. Mussels are usually packed in 2 to 10 kgnet bags and up to 400 kg in total aretransported in a light vehicle van with a coolersystem set between 3-5C.The other two companies that export musselshave an annual production between 600 and1000 tonnes. One of the companies does notsell live mussels during the summer, becauseof spawning and lack of condition of mussels.Usually 5 to 25 tonnes of mussels areharvested per day and the mussels that aresold live are first trained in 25 kg mesh bagsand then dispatched in 1 tonne pallets in arefrigerated lorry. Transportation to Franceusually takes 2 to 3 days.One company does not harvest musselsbetween late January and early May, and thenagain in August and September, basicallybecause of spawning or biotoxin outbreaks.This company is a depurator, dispatch andprocessing centre combined in one. Fromharvesting site to the depuration/dispatch/processing centre mussels aretransported in 1-5 kg tubs or in bags with 800to 1 tonne mussels. They are loaded ontorefrigerated trucks. Then mussels can be eitherdepurated or processed. The packing unitsusually used are 1, 5 and 25 kg net bags ormodified atmosphere packing (MAP), trays of 1to 5 kg. The MAP are sent in a refrigeratedtruck either to France or Ireland. Whereas thenet bags are sent to France.One of the mussel producers complained thatin Ireland the truck transport to the UK orcontinental Europe is limited. Also wholesalersare not up to speed with quality and de-bearding prior to sale.Table 4 Transport duration depending on the client. Inthe second column n means the total number ofcompanies that have a commercial relation with theclients stated in each row.Client nTransportdurationRestaurants in Ireland 4 2 - 5 hFrance depuration/dispatchcentre2 2-3 days
  15. 15. MusselsAliveD 4.115Transport of live musselsThe industry perspective: systems in use worldwideSpainAurelio Silva Abalo, S.A. is a depurationcentre located in Illa de Arosa (North ofSpain). Mussels are harvested in Galiciaand transported to thedepuration centre through aconveyor belt. Once in the depuration centremussels are depurated for 24 hbefore being packed in eitherwooden boxes with ice (5 to 6kg) or net bags of different sizes(5, 10 and 15 kg). Mussels are alwaystransported on ice, and thiscompany has invested in itsown ice production.Figure 5 Aurelio Silva Abalo, S.A. mussel transport at different stepsof the trade chain (Pictures taken from http://www.aureliosilva.eu/)
  16. 16. MusselsAliveD 4.116Systems in use worldwideAustraliaKinkawooka Shellfish is an owner-operatedcompany located in Port Lincoln, SouthAustralia. Mussels, Mytilus galloprovincialis areharvested, de-clumped and graded at sea andkept at a constant temperature in bags with ice.These bags are transportedfrom the vessel to the factory inside chilled binsthus maximizing shelf life. In this area there is noneed to depurate mussels and therefore musselsarriving at the factory are de-byssed, scrubbedand immediately vacuum packed.The mussels are available in 2 grades: Large: 85 mm + shell length with ameat to shell ratio 38 %; Standard: 65-85 mm shell length witha meat to shell ratio of 36-40 %.They are packed in a reduced atmosphere1kg VAC bag, chilled and then placed in a12 kg styrene esky with ice.AFigure 6. Transport of mussels at KinkawookaShellfish from harvest A - chiller bins; B -Bag, to dispatch. Pictures taken fromhttp://www.kinkawookamussels.com.au/default.htmBagAB
  17. 17. MusselsAliveD 4.117Systems in use worldwideCanadaWhereas in Australia and in NewZealand the bag system is used totransport mussels, in Canada tote panand vats (see picture below) are usedcovered with ice to maintaintemperature low.There are both advantages anddisadvantages to using either vats ortotes. Vats offer a better control overquality affecting criteria – temperatureand handling stress. Vats are insulatingand require less ice to maintaintemperature. Therefore cost saving onice purchases may be realized.Moreover, adopting vats in all aspectsof mussel production is HACCP andquality friendly [2].Tote panAdvantages Insulating value keeps productcold Large volumes can betransported, with less handlingand less stress and a higherquality StackableDisadvantages Potential infrastructure limit use,inadequate boat/ barge size,room limitations, low ceilings orsmall spaces at dispatch centre Potential crushing of mussel ifthin shelled or filled improperly CostTote panAdvantages Small and stackable for easytransport Relatively easy to move aboutwhen full CheapDisadvantages No insulating value bythemselves, requires more ice tomaintain temperature Small volume, must have manyon hand for large harvests Large harvest requires muchphysical labourTOTE PAN VAT
  18. 18. MusselsAliveD 4.118Systems in use worldwide - slurry ice technologyThe slurry ice technologyWhether mussels come from Australia, Canada or Spain, there is onepractice that is common to all these markets, that is the utilization of ice tostore and transport mussels. Recently in Canada, the company PrinceEdward Aqua Farms Inc. started using slurry ice from Sunwell, Deepchill™System to pack the mussels and ship them to markets across NorthAmerica.Aquatic food products in general havetraditionally been preserved by packing in ice,either in pounds or boxes, which is a time-consuming strategy [3]. But slurry ice is anefficient alternative to ice flakes.According to Jerry Bidgood, General Managerof Prince Edward Aqua Farms (2006) “Theflake ice system required a lot of manuallabour; ice had to be shovelled into every boxand vat. Ice on the bottom, middle and top.This was OK but it melted quickly anddidn’t cool all the product quickly. Theslurry ice system gave us an automatedmethod for icing that got in between everymussel in every bag, ensuring fast coolingof the entire product. The mussels arecooled down to just above 0°C[4].”Ice slurry is a homogenous mixture of smallice particles and carrier liquid. The liquid canbe either pure freshwater, saltwater or abinary solution consisting of water and afreezing point depressant. Ethanol, ethyleneglycol and propylene glycol are the mostcommonly used freezing point depressants inindustry [5]. Slurry Ice is also known as liquidice, slush ice, flow ice, fluid ice, or by a widerange of trade or brand names.This company takes advantage of slurry icebecause:1. Slurry Ice can be pumped throughregular hoses or pipes, so no moreshovelling and hauling bins or tubs withice cubes or flakes; thereby improvinghygienic handling, and may becombined with other agents, such asozone, to achieve an antiseptic surfaceeffect [6-8];2. Slurry Ice surrounds the musselscompletely, leaving no air pockets, andtherefore capable to extract heatbetter, faster and more efficiently[3] ;3. Slurry Ice is soft and has no jagged orsharp edges, thus preventing injuries ordamages to the product-to-be-cooled[3];Figure 7 Slurry ice used during harvestingfish. Picture by V. Koren.
  19. 19. MusselsAliveD 4.119Systems in use worldwide: the slurry ice technologyThe Prince Edward Aqua Farms process is asfollows:After harvesting, mussels arrive in insulatedcontainers. They are inspected then go toprocessing to be cleaned and graded.They are then placed into wet storage for 24 hto ensure all sand and grit is cleaned out. Thewet storage temperature is supplied andmaintained by pure ocean water in thewinter, and by salt water wells in the summer.As orders arrive, mussels are taken from wetstorage and go through the cleaning, de-bearding and final hand grading.Finally, mussels are packed by weight in meshbags from 1 kg to 11 kg and placed incontainers weighing from 4.5 to 450 kg,according to the customers requests. Thenthey go to the cool room to be iced (Figure8).The icing system uses seawater to produce asmuch as five tons of dry ice, or almost 10 tonsof slurry ice per day. The slurry ice with an icefraction of 50-60% (ice percentage in thedeepchill™) is automatically pumped to fourseparate locations at the facility. At the firsttwo locations the slurry ice is discharged into1 ton bulk containers holding 360-400 kg ofmussels packed in the mesh bags.A third discharge location is found in a chillroom and is used for packing mussels inwaxed boxes of 22, 11 or 4.5 kgconfigurations. Mesh bags of mussels areplaced into the boxes and slurry ice isdischarged over and around the bags. Again,the slurry ice flows into every space andcrevice to provide ultimate contact cooling.The final discharge station is also located inthe chill room, over 150ft (45m) away fromthe deepchill™ generators. It is used forpacking both, the bulk containers and waxedboxes, as well as a re-icing station to maintainmussels that are packed on non-shippingdays.Figure 8: Icing of mussels with slurry ice in acontainer of 450 kg and in card boxes, pictures fromhttp://www.peaqua.com/videos.phpSlurry ice lasts longer because it can bepacked more densely making it possible to getmore ice into the boxes. This company claimsthat mussels in this type of ice have 10 to 12days shelf life whereas with other types of icethe shelf life is only seven days.
  20. 20. MusselsAliveD 4.120Transport of live musselsThe science perspectiveThere are four possible storage conditions forlive mussels: ice, no ice (chilled air) and seawaterat ambient or cooler temperatures. Howeveronly two are feasible in the context of transportand that is ice or no ice.The use of ice prolongs the average shelf lifeof the blue mussel, M. edulis in comparison tomussels held in ambient air temperatureswithout ice or held in chilled rooms without ice[9, 10]. As well, holding mussels under meltingice, as opposed to just in or on ice, can furtherincrease shelf life by more than 5 days [9-11].Recent results obtained by Harding et al.(2004)[12] suggest that producers shoulduse ice as part of their storage practice toreduce stress, increase quality and extendthe value of their product. According tothese authors, late autumn (December)through to the spring (May) of the year iswhen mussels are in the best physiologicalcondition, and can better cope with thestress of handling, processing, and storage. Itwas shown that the benefit of using ice ismore evident during summer months, whenmussels are more fragile (spawning season).In Canada trials were carried out with musselsuncovered, covered but without ice, and iced[2].Mussels left uncovered showed coretemperatures in the tote pan to either staysimilar to ambient temperature or increasedand fluctuated; temperatures were neverbelow 15C.Mussels covered by a tarp showedtemperatures similar to ambient harvesttemperature, increased or fluctuated;temperatures were never below 15C.Mussels that were iced had coretemperatures drop dramatically to 1C within30 minutes of harvest.Figure 10. Graph showing core temperature of musselstransported to processing plant in tote pans: ambient, air,uncovered covered and iced (Figure courtesy Allister Struthers.)Figure 9. Temperature trials under various post harvesttransport conditions uncovered, covered and iced(Photo courtesy of Allister Struthers.)
  21. 21. MusselsAliveD 4.121Adding ice to mussels during harvesting effectively chills the product quickly.Also, holding mussels under melting ice, as opposed to just in or on ice, canfurther increase shelf life by more than 5 days [10, 11]Leaving mussels uncovered and exposed to the wind and hot sun will notonly trigger spawning during summer months but it will also promotedesiccation. It has been reported that mussels begin to suffer significantmortality after 20 % or more of body weight lost through desiccation. Theabsolute loss of weight as water is greater in larger than in smaller mussels,but the percentage loss is greater in the smaller individuals. In this respectit has been suggested that wind is a major factor in accelerating water loss,and an important cause of mortality [13].
  22. 22. MusselsAliveD 4.1224. MusselsAlive TrialSwansea UniversityIn March 2011 mussels were sampled toassess their general condition after severalcritical steps post harvesting and afterdifferent transport conditions. Theparameters measured were: gaping, survival,weight loss and ammonia content in the bloodserum and water mantle cavity. Temperatureduring transport was also registered.The sampling took place in Scotland, at thedepuration site in Achnacloich, and at theScottish Association for Marine Science,(SAMS) located in Oban. Mussels were thentransported to Swansea University in Wales,where they were sampled after transport andafter 24 h re-watering (Figure 11).In Scotland mussels weresampled immediately aftergrading. The mussels werethen separated into 48 bagsof approximately 5 kg. Bags1-24 were placed into a vatfor depuration for 48 hours(7C), the facility was locatedin Achnacloich. The other halfwere stored at 8C in acontrolled temperature roomat the Scottish Association forMarine Science about 20minutes away fromAchnacloich. After about 48 hthe mussels that were notdepurated were picked upfrom cold storage from SAMSand brought to Achnacloichfor sampling with the musselsthat were depurated.The bags were put into 8polystyrene boxes of thesame size (6 bags in each box)alternatively with and withoutice, and with and without alid, as shown in figure 12. The boxes without a lid were stored in the van for transportation on thetop of the other boxes (to avoid being covered over as if covered by a lid). The mussels were thendriven to Swansea in a refrigerated van with temperature conditions set at 7C.Figure 11 Sampling locations.
  23. 23. MusselsAliveD 4.123MusselsAlive TrialAfter 22 h transport mussels were sampled once again at Swansea University, then bags were put ina seawater tank system to be flushed during 24 h. After this, mussels were sampled again. Insummary, there were four sampling points, after grading, after depuration or storage on ice (48 h) ,after 22 h transport and finally after 24 h re-watering. At each stage mussels were sampled to collecteither blood and water mantle cavity to measure ammonia and to assess mortality and gaping.Additionally bags were weighted before and after 22 h of transport. The general experimental set upis shown in the Figure 12.Figure 12 Experimental set up. - blood samples; - water mantle cavity samples; - temperature loggers.M -mortality.No Ice & noLidAfter 22 h transport in net bags 5 kg (six bags per box)to Swansea WalesAfter 24 h Re-wateringSwansea, WalesIce & Lidn=300 MIce No Lidn=300 MNo Ice Lidn=300 Mn=300 SAfter 22 h transport in net bags 5 kg (six bags per box)to Swansea, WalesAfter 24 h Re-wateringSwansea, WalesIce & Lidn=300 MIce No Lidn=300 SNo Ice Lidn=300 MIce & LidWeightn=100 MIce No LidWeightNo Ice LidWeightn=100 MNo Ice & noLidWeightIce & LidWeightn=100 MIce No LidWeightNo Ice LidWeight Weightn=100 MAfter 48 h depurationDunstaffenage, Scotlandn=100 (mortality=M)WeightAfter 48 h dry storageOban, Scotlandn=100 (mortality=M)WeightNo Ice & NoLidn=300 MNo Ice & NoLidn=300 MAfter Grading (0 h)Achnacloich, Scotlandn=30n=100 (survival)
  24. 24. MusselsAliveD 4.124MusselsAlive TrialResultsThis experiment has two elements. The firstprovides a comparison of the consequences ofre-watering, in this case via depuration, inrelation to dry storage on ice, immediatelyafter grading. The second part assesses theadded effect of different transport conditionsas a consequence of the impact of depurationor dry storage.1. Depuration vs. dry storage on iceMortality results indicate that re-wateringmight have a beneficial effect, as only 2 % ofmussels died after depuration comparativelyto the 6 % obtained after dry storage (Figure13). Also there was no gaping afterdepuration but after 48 h of dry storage on ice1 % of mussels were gaping.Ammonia concentration in the serum washigher after 48 h dry storage on ice than afterdepuration (Figure 14).2. Different transport conditionsand re-watering2.1. Temperature in the transport boxesThe temperature in each box was registeredwith loggers. This is similar to the procedureused in Canada and described on page 19. Theambient temperature in the box with ice andlid was maintained at 1 C during the 22 h ofsimulated transport whereas, without the lid,the temperature which was initially low (2 C),increased during transport up to 6 C (Figure15). Without ice but with the lid on thetemperature was kept between 6 and 7 C.Previously it was concluded that adding ice tomussels during harvesting effectively chillsthe product quickly [2]. In this trial it is alsoconcluded that mussels kept in a polystyrenebox with ice and a lid are chilled quickly andmost importantly, they are kept at lowtemperatures (1C) during 22 h of transport.3260 0102468Grading Depuration Ice Storage%MortalityGaping5.104.329.120.002.004.006.008.0010.0012.0014.00Grading 0h Depuration Ice StorageStorage 48 hAmmonia(g/mLserum)Figure 13 Mortality and gaping (%) after grading,after 48 h depuration and after 48 h dry storageon ice.Figure 14 Average ammonia concentration ±STDV inthe serum of mussels after grading, and after 48 hdepuration and ice storage.
  25. 25. MusselsAliveD 4.125MusselsAlive TrialFigure 15 Temperature during different transport conditions. Blue line indicates temperature in each box; A – Ice &Lid; B – Ice & No Lid; C - No Ice Lid; the red dotted line indicates the temperature in the van, slightly above 9C.
  26. 26. MusselsAliveD 4.1261212372601234567Ice&Lid Ice No Lid No Ice Lid No ice&No LidMortality(%)Depurated Non DepuratedMusselsAlive Trial2.2. MortalityAfter transport the mortality was not checked for all 8 boxes ( see Figure 12), but it was between 5 %for depurated mussels transported with ice and lid, and 4 % for the remaining treatments. This resultis not conclusive, though, as there is not enough information for all treatments.After 24 h re-watering mussels that hadn’t beendepurated, and therefore spent 60 h out of water hadthe highest mortalities especially those in boxes withouta lid. In general, even comparing mussels that weredepurated, and only spent 22 h out of water, those inboxes without a lid had a slightly higher mortality (Figure16).Figure 16 Mortality after re-watering considering alltransport treatments: mussels in a box with ice & lid; withice but no lid; without ice but with the lid and without bothice and lid.Figure 17 Re-watering of depurated mussels(Picture courtesy Adam Powell).Figure 18 Re-watering of non depurated musselsPicture courtesy Adam Powell).
  27. 27. MusselsAliveD 4.127MusselsAlive Trial2.3. Weight lossIt is general knowledge that during transportout of the water mussels lose water and thusweight. During the interviews, one musselfarmer who depurates all mussels mentionedthat in his company mussels are packed in netbags (5 kg) but with an excess of weight,usually 5.8 kg per bag but after transportthere is only 5.3 kg left (~ 8 % loss).During the trial conducted at SwanseaUniversity, bags were weighed before andafter transport and even though there is agreat variability between bags, mussels lostweight (Figure 19). In general non depuratedmussels lost more weight than depuratedmussels. Probably this difference would beeven more evident, if mussels had beenweighed before being stored on ice for 48 hand then after the 22 h in different boxes.Because at this stage, non depurated musselshad been out of water for 60 hours. Whereasdepurated mussels had only been out ofwater for 22 h.The results also indicate that there is no realdifference between treatments (boxes) in thenon depurated mussels, with an averageweight loss between 11.8 and 14.2 %.Probably because these mussels hadpreviously been on ice for 48 h. However,there is a tendency for depurated mussel tolose more weight in the box without ice andlid (7.4 %) than in the box with ice and lid (2.7%). The results obtained in the box with icebut without lid (3.8 ± 2.3 %) are slightly lowerthan the number reported by the musselfarmer (8 %), with mussels transported underthe same conditions.2.73.95.87.411.813.311.814.20.02.04.06.08.010.012.014.016.018.0Ice&Lid Ice No Lid No Ice Lid No Ice&NoLidIce&Lid Ice No Lid No Ice Lid No Ice&NoLidDEPURATION NO DEPURATIONAverageweightloss(%)Figure 19 Average weight loss (%) of mussels after transport minus STDV. Two types of mussels were transported:depurated during 48 h and stored on ice during 48 h. Transport treatments: 1) box with ice and a lid (Ice&Lid); 2) boxwith ice but no lid (Ice No Lid); 3) box without ice but with a lid (No Ice Lid) and 4) box without ice and without a lidNo Ice & No Lid.
  28. 28. MusselsAliveD 4.128MusselsAlive Trial2.4 Serum AmmoniaMeasurements of ammonia in blood serumprovide a rapid, quantitative index of thephysiological state of Mytilus edulis [14].Figure 20 depicts the ammonia content in theserum of mussels during several critical stepsof the trade chain.Results indicate that in general ammoniaincreases during emersion and that musselsrecover if re-watered.After 48 h depuration in immersedconditions, ammonia content in the serum issimilar to just after grading, but after thesame period on ice, the ammonia contentincreases. After 22 h on ice with a lid, musselsthat have been depurated have a similarammonia content as mussels that were storedunder the same conditions for 48 himmediately after grading. This could indicatethat a maximum threshold is reached formussels on ice after 24 h. However, if musselsare kept on ice for more than 48 h, in this case60 h, the ammonia content can increasefurther and reach extreme high values (> 20g/mL), but the variability also increases.Without ice but with a lid the ammoniacontent does not reach the maximum valuesthat are reached with ice, especially in thedepurated mussels.Once mussels are re-watered after drystorage, with or without ice, for 22 or 60 h,they all recover, and ammonia levels decreaseto values similar to the initial stage, that isimmediately after grading. This means that re-immersion is an effective recovery step.Figure 20 Average ammonia concentration ±STDV in the serum of mussels during the 84 h experiment, that is immediatelyafter grading, after 48 h depuration and after the same period on ice. These mussels were then transferred to transport boxesunder different conditions during more 22 h, at this stage the experiment was running for 60 h, and then mussels were re-watered during 24 h.5.104.329.065.44 4.91 4.928.8815.1612.395.79 5.820.005.0010.0015.0020.0025.00Grading0 h 48 h Ice&Lid No Ice Lid Ice&Lid No Ice LidTransport 22 h Re-watering24 hAmmonia(g/mLSerum)DepuratedNon Depurated
  29. 29. MusselsAliveD 4.129MusselsAlive TrialPrevious studies reported that a 24h re-immersion process of the mussels followingany of the other processing activities (e.g.washing, de-clumping and grading) reducedthe initial stressful impact of the processingactivity [12]. Survival of mussels had alreadybeen reported to increase by over 30% with a12 h re-immersion period and 50% after a 48hre-immersion period [9] [15]. It has also beenfound that the condition and quality ofmussels can be improved with re-immersionas liquor is recovered, byssal damage isrepaired, and trapped mud can be filtered outof the mussels [9].In general it can be concluded that:1. the duration of dry storage has acumulative effect on mortality andammonia build-up in the blood.2. mussels in polystyrene boxes with ice andlid are chilled quickly and mostimportantly, they are kept at lowtemperatures (1C) during 22 h oftransport. This means that during thisperiod there are no temperaturevariations, thus the cool chain ismaintained.3. Mussels in boxes with a lid suffered lessmortality after re-watering than mussels inboxes without a lid and in general theweight loss during transport was morevariable.4. Re-watering has a beneficial effect aftergrading and after transport.Suggestions for future researchEven though re-watering after de-byssing wasnot tested in this trial, there is evidence thatthis is also most beneficial and recommended[12].Duration of re-watering should be furtherinvestigated, because it might be that 12 h isenough. On the other hand re-wateringduration might be dependent on the type ofprocessing activities that the mussels havebeen through.Storage on slurry ice should be furtherinvestigated.General RecommendationsCoordination is key to avoid delays andbreakdown in product quality. Develop andmaintain a harvest plan that includestransporting product pre and post harvest.Containers must not be overloadedUse care in moving or unloading containers toprevent shock stressMinimize product exposure to sunlight, wind,rain or snow.Record keeping is essential. Check and recordtemperatures of product before loading ontotruck. Check and record temperature at thetime of unloading at the centre. If mussels arebeing held for an extended period of time,continue to monitor and record temperatureson a regular basis.In the following page is a summary of the EUregulations and Codex Alimentariusrecommendations
  30. 30. MusselsAliveD 4.1305.Regulations and recommendationsA) 853/2004, Annex III, Section VII, Chap II, B2B) 853/2004, Annex III, Section VII, Chap VIII, 1C) 852/2004, Annex II, Chap II, 1D) 852/2004, Annex II, Chap IV, 1E) 852/2004, Annex II, Chap IV, 6F) 852/2004, Annex II, Chap IV, 7G) 852/2004, Annex II, Chap IX, 5(*) Codex AlimentariusGeneral The product should be dispatched in the sequence of the lot numbers (*). The cold chain is not to be interrupted (G).However, limited periods outside temperature control are permitted, toaccommodate the practicalities of handling during preparation,transport, storage, display and service of food, provided that it does notresult in a risk to health (G). Live mussels must be kept at a temperature that does not adversely affectfood safety or their viability (B). Temperature should be maintained during distribution to control microbialgrowth(*).Transport Vehicle Means of transport must permit adequate drainage, be equipped to ensurethe best survival conditions possible and provide efficient protection againstcontamination (A). the design and layout of rooms contained for means of transport shouldpermit good food hygiene practices, including protection againstcontamination between and during operations. In particular (C): floor surfaces and wall surfaces - maintained in a sound condition and beeasy to clean (C); ceiling or roof, interior surface of the roof and overhead fixtures are to beconstructed and finished so as to prevent the accumulation of dirt and toreduce condensation, the growth of undesirable mould and the sheddingof particles (C). walls, floors and ceilings, where appropriate, are made of a suitablecorrosion-resistant material with smooth, non-absorbent surfaces. Floorsshould be adequately drained (*). Vehicles should be designed and constructed where appropriate: with chilling equipment to maintain chilled shellfish during transportationto a temperature as close as possible to 0 °C; to provide the fish or shellfish with protection against contamination,exposure; to avoid extreme temperatures and the drying effects of the sun or wind.Containers Must be kept clean and maintained in good repair and condition to protectfoodstuffs from contamination and are, where necessary, to be designed andconstructed to permit adequate cleaning and/or disinfection (D). Should provide sufficient protection of the bivalve molluscs against damage tothe shells from shocks. Are to be placed and protected as to minimise the risk of contamination (E). The bivalve molluscs should not be transported with other products that mightcontaminate them (*) Capable of maintaining foodstuffs at appropriate temperatures and allowthose temperatures to be monitored (F). Bivalve molluscs intended for human consumption should only be distributedin closed packaging (*).
  31. 31. MusselsAliveD 4.1316. References1. Mayes, A.S. and D.I. Fraser, Scottish Shellfish Farm Production Survey. 2011: Edinburgh. p. 25.2. C-ASD, Quality Assurance Guidelines for the Newfoundland Mussel Industry. 2003, Centre forAquaculture and Seafood Development (C-ASD) Marine Institute of Memorial University ofNewfoundland: St. Johns. p. 58.3. Piñeiro, C., J. Barros-Velázquez, and S.P. Aubourg, Effects of newer slurry ice systems on the quality ofaquatic food products: a comparative review versus flake-ice chilling methods. Trends in Food Science&amp; Technology, 2004. 15(12): p. 575-582.4. Liquid ice cools rapidly, evenly and effectively, in Eurofish Magazine. 2009, Eurofish InternationalOrganisation: Copenhagen. p. 82-83.5. Kauffeld, M., et al., Ice slurry applications. International Journal of Refrigeration, 2010. 33(8): p. 1491-1505.6. Rodríguez, Ó., et al., Effects of storage in slurry ice on the microbial, chemical and sensory quality andon the shelf life of farmed turbot (Psetta maxima). Food Chemistry, 2006. 95(2): p. 270-278.7. Campos, C.A., et al., Evaluation of an ozone–slurry ice combined refrigeration system for the storageof farmed turbot (Psetta maxima). Food Chemistry, 2006. 97(2): p. 223-230.8. Campos, C.A., et al., Effects of storage in ozonised slurry ice on the sensory and microbial quality ofsardine (Sardina pilchardus). International Journal of Food Microbiology, 2005. 103(2): p. 121-130.9. Slabyj, B.M. and C. Hinkle, Handling and storage of blue mussels in shell. Research in the Life Sciences1976. 23(4): p. 13.10. Boyd, N.S. and N.D.C. Wilson, Handling and processing of raft-cultured mussels. Symposium on FishUtilisation Technology and Marketing in the Indo-Pacific Fishery Commission Region, F.a.A.O.o.t.U.Nations, Editor. 1978: Rome11. Warwick, J., A Code of Practice for Mussel Processing. 1984, New Zealand Fishing Industry Board:Wellington.12. Harding, J.M., et al., Evaluation of the neutral red assay as a stress response indicator in cultivatedmussels (Mytilus spp.) in relation to post-harvest processing activities and storage conditions.Aquaculture, 2004. 231(1-4): p. 315-326.13. Bayne, B., et al., The physiological ecology of Mytilus californianus Conrad 2. Adaptations to lowoxygen tension and air exposure. Oecologia, 1976. 22: p. 229 - 250.14. Sadok, S., R. Uglow, and S.J. Haswell, Fluxes of haemolymph ammonia and free amino acids in Mytilusedulis exposed to ammonia. Marine Ecology Progress Series, 1995. 129: p. 177-187.15. Prochazka, K. and C.L. Griffiths, Factors affecting the shelf life of live cultured mussels. Journal ofshellfish research, 1991. 10(1): p. 23-28.

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