January | February 2014

Whisky by-products – a sustainable protein source for aquaculture

The International magazine for the aquaculture feed industry

International Aquafeed is published six times a year by Perendale Publishers Ltd of the United Kingdom.All data is published in good faith, based on information received, and while every care is taken to prevent inaccuracies, the publishers accept no liability for any errors or omissions or for the consequences of action taken on the basis of information published. ©Copyright 2014 Perendale Publishers Ltd. All rights reserved. No part of this publication may be reproduced in any form or by any means without prior permission of the copyright owner. Printed by Perendale Publishers Ltd. ISSN: 1464-0058

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Volume 16 / Issue 6 / January-February 2014 / © Copyright Perendale Publishers Ltd 2014 / All rights reserved

Scottish whisky is a truly iconicproduct, with Scotland the largest-producing nation of whisky world-wide. Production has increased by

30 percent in the last decade and morethan five times in the last half-century. In2011 more than 500 million litres of purealcohol (lpa) of whisky were produced inthe UK. As the whisky industry prospers,more attention is drawn to theby-productsofwhiskyproduction.Whisky manufacture yields con-siderableamountsofby-products– which include liquid and solidcomponents–alongsidethemainproduct.These materials containsignificant amounts of proteinsthat are currently underutilisedandareoftenperceivedasachal-lenge rather than anopportunityfordistillers.

The salmon farming indus-try, with a growing demand forproteins to satisfy the nutritionalrequirements of their fish stocks,could take advantage of the pro-teins available from whisky by-products.By reducing the relianceonwild fishand importedproteinsources (e.g. soybean meal) tomeet the needs of an expand-ing market, UK aquaculture couldbenefiteconomicallyfromalocallysourcedsustainableproteinsupply.Symbioticrelationshipssuchasthiscan help to secure the long-termsustainability of the aquacultureindustry to meet the nutritionalrequirements of an expandingworldpopulation.

An understanding of thenutritional, chemical and physicalproperties of whisky by-products,

thedevelopmentof sustainablemethods forproteinrecoverysuitabletotheneedsofbothwhiskyandaquacultureproducers,andamas-teryoftheeconomicsbehindtheprocessandproductareessential toensurea sustainablelarge-scaleprotein supply to the aquaculturefeedsector.

“Horizon Proteins” is a collaborativeresearch project based at Heriot-Watt

University in Edinburgh, Scotland. The teamhasbeenworkingonaproteinrecoveryproc-ess from brewery and distillery by-productssince 2011. This article will focus on thenutritionalpropertiesandquantitiesofproteinthat could be potentially recovered fromwhisky by-products and particularly pot aleanddraff,whicharebothproducedduringthemanufactureofmaltwhisky.

Whisky and whisky by-products

Whisky spirit is produced fromeither malted barley as the solecereal substrate or a mixture ofunmaltedcerealgraintogetherwithmalted barley. It is important todistinguish between the two kindsof whisky (malt and grain) and thecereals used in the process, sincethepropertiesofthewhiskyanditsby-productsdiffersubstantially.

The production of malt whiskyinScotlandrequiresonly threerawmaterials: barley, yeast and water.Nothing more, nothing less. This isa statutory requirement under theScottish Whisky Regulations 2009.Scottish malt whisky can only bemade (and, since 2012, bottled) inScotlandsothisholdsworldwide.

Consequently, the by-productsfrommaltwhiskyoriginatefromtheraw materials mentioned above.There are various types of by-products, but from a nutritionalperspective, two are of particularimportance. Draff (also known asspent grains) is a solid by-producttypically containing 70-85 percentmoisture and at least 20 percentcrude protein content on a drymatterbasis.Theotherprotein-richby-product is pot ale. Pot ale is

Whisky by-products – a sustainable protein source for aquacultureby Julio Traub, PhD student, Heriot-Watt University, Edinburgh, Scotland

table 1. Malt and grain whisky by-products.

Malt Whisky Pot ale: residues from first distillation, also known as “Burnt ale”. liquid substance that contains typically 5% solids and at least 40% protein on dry matter basis.Spent lees: residual liquor after second distillation. Mostly water, but also contains some volatile components. nutritive value is negligible and normally treated in bio-plants.Draff: grain solids left after starch and enzyme extraction. Sometimes referred as distillers' grains and used as animal feed. It contains typically 70-85% moisture and at least 20% protein on a dry matter basis.

Grain Whisky Spent Wash: liquid residue after distillation. Comparable to pot ale from malt whisky productionSpent Grain: the equivalent of draff in grain whisky production.

Figure 1: Historical malt whisky production in Scotland 1946-2012 (Source: Scotch Whisky Association)

20 | InternatIonal AquAFeed | January-February 2014

FEATURE

January-February 2014 | InternatIonal AquAFeed | 21

a liquid substance that contains typically 5percentsolidsandatleast40percentproteinon dry matter basis. A list of distilling by-productsandtheirdefinitionsarepresentedinTable1.Figure2showsasimplifiedproc-essdiagramofmaltwhiskyproduction,whichincludes rawmaterials, by-products and themainstepsoftheprocess.

Whilst whisky by-products have well-establishedmarkets inScotland,currentusesdonot specificallyexploit theparticularpro-tein content of these materials. Currently,draffandpotaleareusedas foodforcattle,energy recovery, fertiliser and feedstock foranaerobicdigestion.However,inthemedium-to long-term, with bioethanol plants (whichalso produce plentiful cereals by-products)coming online, there will be an increasingcompetitionfordistillers.Additionally,current

processing technologies relyon energy-intensive methods.Hence,duetoincreasingenergycosts and increased competi-tion, distiller’s by-products willhavea reducedpotential valueto the whisky industry. Findingalternative markets for theseby-products is important fromaneconomicandasustainabilityperspective.

Barley and yeast in aquaculture feeds

To understand the nutritional propertiesof the whisky by-products it is necessary toreview their components, specifically barleyandyeast.Barleyhasbeenincorporatedinani-malfeeddiets,buthasnotbeenwidelyused

in aquafeeds for several reasons. Economicaland nutritional considerations have played akeyroleinthesedecisions.

Compared to other plant feedstuffs usedinaquafeeds (seeTable3),barleyhasa lowproteincontent(15percentcomparedto49percentforsoybeanmeal).However,agoodamino acid profile makes the barley proteinitselfasuitablecandidateforaquafeeddiets.

table 2. Chemical composition and feeding values of malt distillery by-products. (2)

Draff Pot ale

Dry Matter (g kg-1) 258 40Crude protein (g kg-1 DM) 198 350

ether extract (g kg-1 DM) 82 22Crude fibre (g kg-1 DM) 173 -

ash (g kg-1 DM) 33 105Ca (g kg-1 DM) 1.7 1.6

P (g kg-1 DM) 3.7 22.0Mg (g kg-1 DM) 1.4 6.6na (g kg-1 DM) 0.9 1.1

K (g kg-1 DM) 3.7 23.0S (g kg-1 DM) - 6.8

Cu (g kg-1 DM) 10 133Mn (g kg-1 DM) 43 17Zn (g kg-1 DM) - 18Co (g kg-1 DM) 0.02 0.11Se (g kg-1 DM) 0.02 -

Metabolisable energy value (MJ kg-1 M) 10.8 14.2Degradability of crude protein 0.80 0.95

Figure 2: Malt whisky production process

20 | InternatIonal AquAFeed | January-February 2014 January-February 2014 | InternatIonal AquAFeed | 21

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Theotheressential component inwhiskyproduction is yeast. Although the volumesofyeastcomparedtobarleyaresubstantiallysmaller(typicallya60to1ratioofbarleytoyeast is used inmaltwhiskyprocessing), thenutritional properties of yeast are worthconsidering.

PreviousarticlesinInternationalAquafeedhave reviewed the nutritional properties ofyeast,but tosummarisehere,onadrymat-terbasisyeastcancontainup to50percentprotein.Additionally,othercomponentsben-eficialtoaquaculturecanbefoundindistillersspentyeastsuchasnucleotidesandβ-glucans.

Protein supply from whisky by-products

Considering all themaltwhiskydistilleriesin Scotland, proteins contained in pot alecouldpotentiallysupplyatleast40,000tonnesperannum.Includingdraff,thecombinedpro-

teinoutput fromUKmaltwhiskycouldofferup to 70,000 tonnes per annumof proteinstotheanimalandaquaculturefeedmarkets.

Average outputs of whisky by-productsarereportedinTable4below.Typically,solidby-productsfrommaltwhiskydistillationhaveabiggeroutputperlitreofpurealcoholthangrainwhiskydistillation,butitistheotherwayroundforliquidby-products.Thisisexplainedby the fact that the quantity of starch con-vertible intoglucose is greater in thecerealsusedforgrainwhiskythanthoseusedfortheproductionofmaltwhisky.

Market valueThemarketvalueofwhiskyby-productwill

dependonseveralfactorsincludingtheirproteinandmoisturecontent.Ultimatelyhowever,theirprice will be driven by international prices forfishand soybeanmeal.Basedon these factors

and current protein prices,it could be estimated thatprotein recovery frommaltwhisky co-products couldbe worth up to £140mperannumacrossScotland.Other fermentation proc-

esseswithby-productssimilartothemaltwhiskyindustry,includinggraindistilleries,breweriesandbiofuels,couldrepresentaproteinsourceworthmorethan200,000tonnesannually,equivalentto£150-450minproteinsalesacrosstheUK.

Protein demand for salmon farmingWorldwide, farmed salmon and trout pro-

ductionreached2.5milliontonnesin2009.Themainspeciescultured(Atlanticsalmon,RainbowtroutandCohosalmon)accountedforaround95percentoftotalsalmonandtroutproduction.Thecombinedoutputofthetopthreeproduc-ers(Norway,ChileandUK)representedmorethan70percentoftheworld'stotaloutputofthefish.

Protein requirements for the species men-tioned above could include up to 50 percentof their feed’s ingredients, which equates to aprotein demand of at least 1.3 million tonnesgloballyonanannualbasis.Proteindemandforsalmon and trout feeds in the UK is approxi-mately85,000tonnesperannum.

The aquaculture industry is set to expandin the coming years and its protein demandwillconsequentlyfollow.IntheUKalone,a50percentincreaseinsalmonandtroutproductionis expected by 2020, which translates into aproteinconsumptionofatleast150,000tonnesannually.

ConclusionScotch whisky and Scottish aquaculture

could develop beneficial industrial synergies.The proteins found in whisky by-products arenutritionally comparable to proteins used inthecurrentlyavailablefishfeedingredients,andtheirpotentialvolumesareenoughtosatisfytheScottish salmon farming industry and achievesubstantialproteinsourcingbenefits,ineconomi-calandsustainabilityterms.Whiskyby-productscanofferasustainablesupplyofsuitableproteintotheaquacultureindustry.

Thereisaneedtoidentifyappropriateandsustainabletechniquestoobtaintheseproteinson an industrial scale. At Horizon Proteins, aScottishresearchteamisdevelopingasustaina-bleprocessforproteinrecoverythatcouldhavemuch more financial viability than traditionaltreatmenttechnologies forwhiskyby-products.The savings are not only shown economically,but through the significant reduction in energyrequirementsinprocessing,reducingtheincreas-ingly important global warming impact of theoverallprocess.

table 3. typical composition (as-fed basis) of fish meal and various plants feedstuff .(3)

Ingredient Protein(%)

lipid(%)

ash(%)

lysine(%)

Methionine(%)

Cystine(%)

Fish meal 72.0 8.4 10.4 5.57 2.08 0.74Barley 14.9 2.1 2.9 0.44 0.16 0.24

Canola 38.0 3.8 6.8 2.27 0.70 0.47Corn 8.5 3.6 1.3 0.25 0.17 0.22

Soya bean meal 48.5 0.9 5.8 3.08 0.68 0.75Wheat 12.9 1.7 1.6 0.36 0.21 0.27

table 4. By products outputs per litre of pure alcohol (2)

Malt Grain

Solid by-products 3.5-5.5 kg 1.0-1.25 kg

liquid by-products 8.8-11.5 l 16-21 l

Malt whisky by-products: pot ale (left) and draff (right)

Potentially70k tonnes p.a.ofproteininmaltwhiskyby-productsacrossScotland

Potentially£140m p.a.worthofproteininwhiskyby-productsacrossScotland

22 | InternatIonal AquAFeed | January-February 2014

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January-February 2014 | InternatIonal AquAFeed | 23

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farm is bound to produce 7,000 tonnesutilisinganareaof57hectares(seeFigure2).Nevertheless, recent production problemsthathavearisenhaveunfortunately compro-mised this turbot farm to attain full capacityproductionalreadythisyear.

The Acuinova layout is a double row ofeightproductionunits.Eachproductionunithasonejuvenilepavilionandeightgrowthpavilions.In the overhead shot of Figure 2, the juvenilepavilions are coloureddarker than the growthpavilions. Each juvenile pavilion (see Figure 3)has3040m2tanksfor10-100gturbot,makinga totalof480 juvenile tanks, andeachgrowthpavilioninturnhas20113m2growthtanksforfish from100gr. tocommercial size ina totalof 1,248 growth tanks (see Figure 4). At fullcapacityitwillcreatemorethan200directand600indirectjobs.

Ten-gram juvenile turbot are broughtweekly from one of the Spanish company’sturbot hatcheries toAcuinovaMira. Fish areautomaticallyandmanually fed,up to twelvetimesdailywithjuvenilesanduptofourtimesdaily in thegrow-outphase,until they reachthe commercial size of 1-1.5 kg which maylast between 600 and 750 days. Acuinovahastwopumpingstations,thewaterintakeislocated2.4 kmoffshore, eachoneequippedwithnine250kWpumpsprovidinga10.8m3

persecondwater flow,enoughtoprovideadailywatersupplyforacitythesizeofMadrid.

Another Portuguese turbot farm,Piscicultura do Rio Alto, located in Estela innorthern Portugal (see Figure 5), producedturbot from 1993 to 2011, when it wasdecided to abandon turbot production andfarmSenegalesesoleinstead.Atpresent,thisaquacultureunitisundergoingmajormodifica-tionsafterbeingboughtthisyearbyaSpanishcompany (Sea8Porto) tobeconverted intoa hatchery for Senegalese sole, which will

be grown in anoth-er unit in Portugalrecently acquiredfor the purpose.Beginningproductionin1997,theAquacriaPiscícolas facility wasthe third flatfishunit constructed inPortugal. This high-tech flatfish farm islocatedinTorreirainthenorthofPortugal,andistheonlyaqua-culture facility in thecountry operatingwithshallowracewaysystem technologyin conjunction witha recirculation aqua-culturesystem(RAS)for the growth outphase of Senegalesesole production,allowing the fishfarm to substantiallyreduce its environ-mental impact (seeFigures6,7).

In 2011, duringthe management ofits previous own-ers, the flatfish farmbegan its expansionpolicy, which wasalready concluded.Therefore, produc-tion of Senegalesesole will be substan-tially increased, withanoutputof350-400tonnesestimatedfor

Figure 2

Figure 3

24 | InternatIonal AquAFeed | January-February 2014 January-February 2014 | InternatIonal AquAFeed | 25

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Successful moisture control in aquatic feeds

Current challenges and opportunities in amino acid nutrition of salmonids

Volume 17 I s sue 1 2 014 - J ANuARY | F eBRuARY

INCORPORAT ING f I sh fARm ING TeChNOlOGy

Whisky by-products: – a sustainable protein source for aquaculture

Closing the food waste loop: – a new angle for insect-based feeds

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