Quality aspects of fillet, loin and tail products made from live-stored feed-deprived

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1 Qulity spects of fillet, loin nd til products mde from live-stored feed-deprived Atlntic cod (Gdus morhu L.) t different times post mortem. Authors: Ttin N. Ageev b, Rgnr L. Olsen, Sjurdur Joensen b, Mrgrethe Esissen Nofim AS, Muninbkken 9-13, Breivik, P.O. Box 6122, NO-9291 Tromsø, Norwy b Norwegin College of Fishery Science, UiT The Arctic University of Norwy, N-9037 Tromsø, Norwy Corresponding uthor: Nofim AS, Muninbkken 9-13, Breivik, P.O. Box 6122, NO-9291 Tromsø, Norwy. E-mil: ttin.geev@nofim.no (Ttin N. Ageev) Keywords: Atlntic cod, live-storge, strvtion, time of filleting, product qulity 1

2 Abstrct During lst decde, the mount of live-cught Atlntic cod stored in se cges hs incresed. However, the issues of feeding regime during live-storge nd time of processing fter slughter re centrl to provide high qulity products. The gol of this study ws to investigte how the qulity of fresh fillet, loin nd til products cn be ffected by the length of feed-deprivtion nd the processing time post mortem. Feed-deprived cod were slughtered fter 2, 26, 54 or 82 d. On the lst three smpling dys, the three products were mde 4, 6, 10, 14, 24 nd 48 h post mortem. All products were then stored in ice until dy 7 post mortem before nlysing product qulity. The results demonstrted tht prolonged feed deprivtion nd time of filleting ffected both the biochemicl nd the sensory properties of the muscle. Feed deprivtion resulted in fillets hving higher wter content, geltinous texture, typicl white colour nd less fresh se odour. These chnges in product qulity occurred minly fter 54 d of feed deprivtion. The til products were more prone to the contrction nd hd higher drip loss thn loins nd whole fillets independently of the period of feed deprivtion nd time of filleting. 2

3 1. Introduction For the lst decde, live-storge of wild Atlntic cod (Gdus morhu L.) hs been developed in Norwy s method to extend the mrketing seson of fresh cod throughout the yer (Dreyer, Nøstvold, Midling, & Hermnsen, 2008). Although the concept is growing, it is still mrginl, reching supply of only tonnes fresh cod in Norwy in 2016 (The Norwegin Fishermen's Sles Orgniztion, 2016). There re severl dvntges when keeping wild cod live ner fish processing plnts; such s continuous ccess to fresh rw mterils, the possibility of long-term plnning of production, pre rigor processing of cod nd better mrketing prospects (Dreyer et l., 2008). The Norwegin regultion sttes tht wild cod cn be held in se cges for up to 12 wk fter cpture. The first four weeks of live-storge cn be done in the bsence of feeding (FOR , 2004). The extension of the live-storge period without feeding is preferble since wild cod do not esily ccept formulted feed. However, the welfre nd the qulity of the fish must not be compromised (Sæther et l., 2016). The qulity of the rw mteril hs strong effect on the processed products (Akse, 2005; Kiessling et l., 2007), nd thus, it is importnt to explore the fctors tht cn ffect the biologicl sttus of live-stored cod. It is known tht prolonged feed deprivtion nd time of processing re fctors tht cn strongly ffect the muscle qulity of fish. Long-term strvtion of Atlntic cod mkes the fish metbolise muscle nutrients, leding to decresed protein concentrtion, incresed wter content nd softening of fillet texture (Berdll & Johnston, 1983; Blck & Love, 1986; Love, 1988). The fillet texture is lso influenced by the time of processing since pre rigor produced fillets get firmer texture thn fillets mde post rigor (Jørpelnd, Imslnd, Stien, Bleie, & Roth, 2015; Kristoffersen et l., 2006; Kristoffersen, Vng, Lrsen, & Olsen, 2007). The texture is criticl qulity prmeter of fish both for the processors nd for the consumers. In fct, it hs been reported tht soft texture cn cuse downgrding of frmed slmon, resulting in s much 3

4 s 40% loss in vlue (Michie, 2001). The wter content of fish muscle is nother qulity spect tht is of importnce. Specificlly, loss of wter is economiclly equivlent to loss of met by weight, nd the liquid ccumulted in the product pckge cn be unttrctive to consumers s well s contining nutrients from the muscle (Foegeding, Lnier, & Hultin, 1996; Kristoffersen et l., 2007). To our knowledge, most reports on chnges in fish qulity re bsed on dt obtined from whole fillets. Tody however, fish processers commonly produce different fillet products like loins nd tils. There is limited knowledge on how feed deprivtion prior to slughter nd time of processing post mortem ffect properties of such different fillet sections. The gol of this tril ws to study the qulity of fresh products (fillet, loin nd til) mde from feed-deprived cod t different times post mortem. Qulity spects investigted were product contrction, drip loss, muscle hrdness, wter content nd sensory spects like texture, colour nd odour. 4

5 2. Mterils nd methods 2.1 Fish nd smplings The work ws crried out in complince with Norwegin veterinry uthorities (Code number: 7327). Atlntic cod cught by demersl seine were kept live in se cge nd trnsported to onshore fcilities 8 d fter ctch. Feed-deprived fish were slughtered 2, 26, 54 or 82 d fter cpture. The biologicl dt of the Atlntic cod, procedures of cpture, trnsport, tgging, livestorge condition nd slughter procedures re described by Ageev, Jobling, Olsen, nd Esissen (2017). 2.2 Experimentl design nd smple preprtion On the first smpling dy (2 d post-hrvest), 10 fish were filleted nd skinned by hnd 24 h post mortem. On the remining smpling dys (26, 54 nd 82 d post-hrvest), 10 fish were filleted nd skinned 4, 6, 10, 14, 24 or 48 h post mortem. The fillet obtined from the right side of ech fish ws studied s whole fillet, while the left side fillet ws cut into loin (the upper dorsl bck re of the fillet, length: 28 cm) nd til (length: 20 cm). The initil length nd weight were mesured on ech product, nd the individul products were put into numbered plstic bgs (350x650 mm). Then, the products were plced s single lyer in plstic boxes, covered with ice, nd stored in cold room (0 o C) until dy 7 post mortem. On this dy, the mesurements of the length nd weight of the fillets, loins nd tils were repeted. The chnges in length (contrction) nd weight (drip loss) during ice storge were expressed s percent of the initil vlues determined t the time of filleting. 2.3 Physicochemicl nlysis At dy 7 post mortem muscle hrdness, ph nd wter content of the fillets were mesured. Muscle hrdness ws ssessed by performing the compression test s described by (Ageev, Olsen, Joensen, & Esissen, 2018). The compression force (CF [N]) ws nlysed on skin side, 5

6 bout 7-8 cm from the nterior edge of ech fillet nd 1 cm bove the lterl line. For ech mesurement, the recording ws repeted four times, nd the verge vlue ws clculted. Muscle ph ws determined immeditely fter muscle hrdness mesurements by inserting Hmilton double pore glss electrode (Hmilton Bonduz AG, Bonduz, Switzerlnd) of WTW 330/set-1pH-meter (Wissenschftliche-Technische Werkstätten GmbH, Weilheim, Germny) 1 cm into the muscle in the loin prt on the cut side of the fillet. Anlysis of wter content ws crried out on five muscle smples (200 ± 20 g) cut from the loin prt of the whole fillets, nd the smples from ech experimentl group were chopped together in precooled Stephn mixer (Type UM 12, Germny) for 3 x 5 sec. Then three replics (10 g) of the mince were dried t 103 ± 2 o C for h. 2.4 Sensory nlysis The whole fillets (right side) were evluted by n expert pnel of three persons by using the fillet index method (Esissen, Dhl, Eilertsen, Gundersen, & Sivertsvik, 2008) with minor modifictions. The ttributes given demerit scores were odour (0: se fresh, 1: neutrl, 2: fishy, 3: mmoni/sour), gping (0: none - 5: disjointed fillet), fillet surfce (0: dry nd shiny - 2: dispersed), colour (0: homogeneous white, 1: milky-white/non-trnsprent, 2: grey/yellow/reddish) nd texture (0: nturlly - 3: severe soft). The sum of ll scores ws used s fillet index to evlute the qulity chnges occurring due to different filleting time. However, it hs been shown tht strved cod my develop geltinous (sloppy) texture nd n typicl white colour (Love, 1988; Sæther et l., 2016). These properties re not covered by the fillet index method. Thus, the intensity of these ttributes ws evluted in this experiment: typicl colour (0: nturlly, 1: typicl white), geltinous texture (0: none, 1: prtly geltinous nd 2: severe geltinous). 6

7 2.5 Sttisticl nlysis The dt were nlysed using The Unscrmbler version 10.3 (CAMO Process AS, Oslo, Norwy). Prior to the nlyses, the vribles were weighted by 1/STDEV in order to stndrdise the dt to the sme scle. Principl Component Anlysis (PCA) ws used to identify the differentition mongst smples on the bsis of biologicl, physicochemicl, sensory nd instrumentl dt. Prtil Lest Squre Regression (PLS) with Mrtens Uncertinty Test were pplied to identify the significnt effect of feed deprivtion, time of filleting nd size of fish on contrction, drip loss, muscle hrdness nd sensory ttributes of the products. Anlysis of vrince ws crried out to determine the significnt differences between tretment groups filleted t different time points t ech smpling nd the differences between groups filleted t the sme time point post mortem obtined on different smpling dys. A twosmple t-test ws used to explore the differences between loins nd tils mde t the sme filleting time within the sme smpling. A two-smple t-test ws lso used to exmine the differences in muscle hrdness (N) nd wter content (%) in fillets mde t the sme time point post mortem obtined on different smpling dys. 7

8 3. Results nd discussion In order to identify ny differentition in dt due to time of feed deprivtion s well s time of filleting, weighted principl component nlysis (PCA) ws performed on mtrix with 190 objects (fish) nd 11 vribles. The vribles used in the nlysis were time of feed deprivtion, time of filleting, length nd gutted weight of cod, muscle ph, muscle hrdness, contrction, drip loss, fillet index, geltinous texture nd typicl colour of the fillets. The score nd correltion loding plots showed tht the two principl components (PC-1 nd PC-2) explined 54 % of totl vrition in the dt (Fig. 1). In the score plot, the cod subjected to feed deprivtion for 82 d fter cpture were distinct from the other fish groups. This distinction pttern follows minly PC-1, nd ccording to the correltion lodings plot the most feed-deprived cod (82 d) is ssocited with geltinous texture nd typicl colour, s well s higher fillet index nd higher muscle ph. On the other hnd, the fillets cut from cod exposed to shorter periods of feed deprivtion hd higher fillet contrction nd muscle hrdness. Further, the chnges in drip loss, contrction nd muscle hrdness re lso explined by PC-2, which is relted to the time of filleting (not shown in the figure). It ppers tht fillets mde erly post mortem got higher contrction degree nd muscle hrdness. In order to get n overview on how feed deprivtion, time of filleting nd size of fish (length nd gutted weight) influenced the qulity prmeters of the fillet, prtil lest squres (PLS) nlyses were run. The results of the nlyses re summrized in Tble 1. The size of fish (length nd gutted weight) significntly ffected muscle ph, muscle hrdness, drip loss nd fillet index, ll being higher for smller fish. Higher ph in smller cod hs been previously reported by Love, Robertson, Smith, nd Whittle (1974). It is lso shown tht gping ws significntly influenced by size, giving lower score for gping in smller fish. In ddition, smller fish, s mesured by gutted weight, were more prone to develop geltinous texture nd typicl colour. Feed deprivtion significntly decresed muscle hrdness nd odour, incresed 8

9 wter content nd fillet index, s well s occurrence of geltinous texture nd typicl white colour. Time of filleting lso significntly influenced the qulity prmeters. Erly filleting provided higher muscle hrdness, more contrction nd drip loss, lower wter content, lower fillet index, less gping nd less occurrence of geltinous texture nd typicl white colour. In the following, ttributes tht were significntly ffected by the feed deprivtion nd time of filleting re presented in more detils. 3.1 Contrction nd drip loss of loin nd til products Regrding contrction nd drip loss, no noticeble differences were found between whole fillets nd loins (results not shown). However, differences were found between loin nd til products, nd the results obtined on smpling dys 26, 54 nd 82 fter ctch re presented in Fig. 2. As expected, pre rigor loins nd tils (4, 6, 10 nd 14 h fter slughter) contrcted more thn loins nd tils produced fter the estblishment of rigor mortis (24 nd 48 h post mortem), independent of the durtion of feed deprivtion (Fig. 2 A nd B, Appendix A, Tble A.2). The chnges in fillet length due to rigor contrction re well known, nd hve been reported in severl studies (Jørpelnd et l., 2015; Kristoffersen et l., 2007; Misimi, Erikson, Digre, Skvhug, & Mthissen, 2008; Mørkøre, Thirovic, & Einen, 2008). Further, tils seem to contrct slightly more thn loins during the development of rigor mortis. On smpling 26 d fter cpture, tils (Fig. 2 B) mde 4, 6, or 10 h post mortem contrcted significntly more thn loins (Fig. 2 A) mde t the sme time (Appendix A, Tbles A.1 nd 2). Prolonged feed deprivtion resulted in grdully reduction in til contrction (Fig. 2 B, Appendix A, Tble A.2). On the other hnd, there ws no reduction in contrction of loins during the feed deprivtion for up to 54 d, but the contrction of loins ws significntly reduced fter 82 d of feed deprivtion (Fig. 2 A, Appendix A, Tble A.2). Specificlly, the loins mde fter the onset of rigor (14, 24 nd 48 h post mortem) contrcted significntly less thn tht detected during the previous two smpling dys. 9

10 The different pttern in reduction of contrction in loins nd tils towrds the end of feed deprivtion my be due to the tils hving higher rtio of drk nd white muscle nd the tils differing in geometric shpe, i.e. thin with high surfce to volume rtio. The drk muscle is locted ner the lterl line of the fillet, nd the proportion of drk to white muscle increses towrd the til region (Foegeding et l., 1996). In ddition, in this experiment the pin bones were cut from the loins, resulting in even less mounts of drk muscle in these products. It is known tht the drk muscle re richer in mitochondri, lipid nd glycogen content thn white muscle (Buttkus, 1963; Cppeln & Jessen, 2002; Foegeding et l., 1996), nd thus, it cn hve different rigor development. For instnce, Stien, Suontm, nd Kiessling (2006) reported slightly fster initil rigor contrction in the posterior prt of the fillet thn in the nterior re in rinbow trout. It hs lso been shown tht the contrction in length cn be three times higher in red thn in white muscles in lingcod (Ophiodon elongtus) (Buttkus, 1963). Further, it is lso known tht long-term feed deprivtion leds to the cod utilizing muscle nutrients, depleting glycogen nd ATP reserves, which in turn limit post mortem glycolysis (Blck & Love, 1986; Foegeding et l., 1996; Love, 1988). Thus, it is most likely, tht energy reserves in red muscle in both products decresed with prolonged feed deprivtion. Since the proportion of red to white muscle is higher in tils thn in loins, nd tils re thinner with higher surfce to volume rtio, it is possibly tht tils were more prone to chnges in length due to both rigor contrction nd feed deprivtion. In ddition to the reduction in length, chnges in product weights were observed due to drip loss during storge (Fig. 2 C nd D, Appendix A, Tbles A.1 nd 3). However, the chnges in drip loss both in tils nd in loins were not significntly dependent on the time of filleting. This is in greement with Akse, Kristinsen, Tobissen, Dhl, nd Eilertsen (2008) who reported lmost equl drip loss in pre nd post rigor loins mde from Atlntic cod feed-deprived for four weeks. On the other hnd, it is well known, tht drip loss during storge cn be strongly 10

11 influenced by rigor contrction, resulting in incresed drip loss in pre rigor mde fillets (Jørpelnd et l., 2015; Kristoffersen et l., 2006; Kristoffersen et l., 2007). There were, however, cler differences in drip loss between loin nd til products, where ll tils lost more weight thn loins independent of the durtion of feed deprivtion nd the time of filleting. (Fig. 2 C nd D, Appendix A, Tbles A.1 nd 3). The greter surfce to volume rtio in the tils will probbly result in the loss of more muscle liquid. The fct tht tils were more prone to contrction thn loins my lso contribute (Fig. 2 A nd B, Appendix A, Tbles A.1). Muscle shrinkge, occurring during rigor contrction, forces the mobile wter from intrmyofibrillr spces into the extrmyofibrillr res in the muscle cells where it is more esily lost s drip during storge (Bertrm, Purslow, & Andersen, 2002; Huff-Lonergn & Lonergn, 2005; Offer & Trinick, 1983). Further, it is of interest tht the differences in drip loss between til nd loin products ppered to be reduced towrds the termintion of the experiment. This occurred due to reduction in drip loss in tils nd not in loins. The differences between the products remined significnt for up to 54 d of feed deprivtion while fter 82 d of feed deprivtion, they were less distinct (Fig. 2 C nd D, Appendix A, Tble A.1). It is difficult to explin this reduced drip loss in tils fter prolonged feed deprivtion. A reduced liquid loss of whole fillet fter feed deprivtion hs been reported erlier for slmon (Slmo slr L) nd Atlntic cod (Akse et l., 2008; Mørkøre et l., 2008; Olsson, Gundersen, & Esissen, 2006). 3.2 Muscle hrdness nd wter content The mesurements of muscle hrdness nd wter content were crried out in the loin re of the whole filet. As found by the PLS-nlyses (Tble 1), feed deprivtion nd time of filleting significntly influenced both vribles, however, muscle hrdness were lso ffected by the size of fish (length nd gutted weight). Furthermore, previous reserch hve demonstrted correltion between body length nd texture in fillet. Love (1988) observed positive 11

12 correltion between body length nd texture of heted fish; the lrger fish hd firmer texture. Bjørnevik et l. (2016) nlysed texture in rw cod nd reported tht the fish with higher growth rte hd softer muscle texture. In order to study the direct impct on texture of feed deprivtion nd time of processing in the present study, the length ws used s covrite in the sttisticl evlution of muscle hrdness. The results showed tht fillets from the most feed-deprived cod hd softer texture thn fish feed-deprived for 54 d (Fig. 3). However, only the fillets mde fter the onset of rigor development (14, 24 nd 48 h post mortem) differed significntly (Appendix A, Tble A.4). In ddition, not surprisingly, the fillets from cod strved for 82 d hd higher wter content independent of time of filleting (Fig. 3). This could contribute to the softening of muscle during feed deprivtion, s discussed by Love (1988). The higher proteolytic ctivity becuse of incresed protein ctbolism in muscle of fish feed-deprived for prolonged period my lso contribute to the reduced muscle hrdness (soft texture). Our results re contrdictory to the results reported by Hgen nd Solberg (2010) who showed tht feed deprivtion of Atlntic cod for 11 wk gretly improved fillet texture. However, the texture ws mesured s sher force nd the results were suggested to be linked to the strengthening of connective tissue due to feed deprivtion. It ppered tht the fillets mde erly fter slughter were firmer nd hd slightly less wter in the muscle (Fig. 3, Appendix A, Tble A.4). This is probbly due to unrestricted rigor contrction (Fig. 2 A nd B) nd slightly higher drip loss (Fig. 2 C nd D) in pre rigor thn post rigor mde products. Other scientists hve lso shown tht the time of filleting cn significntly ffect the content of wter in fillet, resulting in pre rigor produced fillets hving lower wter content (Jørpelnd et l., 2015; Kristoffersen et l., 2006). The differences in muscle hrdness between the fillets mde erly nd lte post mortem becme clerer in fish feed-deprived for 82 d (Fig. 3). This could be explined by the higher wter content nd higher proteolytic ctivity in the muscle of such fish s mentioned erlier. 12

13 3.3 Sensory evlution The chnges in fillet index due to feed deprivtion nd time of filleting re presented in Tble 1. The sensory pnel lso stted tht fillets produced from the most feed-deprived cod hd more neutrl odour, brighter colour nd softer texture independently of time of filleting. Similr results hve lso been reported for feed-deprived slmon where the group strved for 86 d hd fillets of less cidulous flvour nd brighter colour compred to the groups strved for shorter periods (Einen & Thomssen, 1998). Furthermore, ll fillets produced before the onset of rigor mortis (during the first 10 h post mortem) in our study, hd less gping nd firmer texture thn the reminder groups. This is in ccordnce with previously reported results for cod (Kristoffersen et l., 2006; Kristoffersen et l., 2007). The number of fillets hving geltinous texture nd typicl white colour incresed towrds the end of the feed deprivtion (Tble 1). It ppered tht those two defects could occur either simultneously on the sme fillet or seprtely. After 26 d of feed deprivtion, only 1 of 60 fillets ws described to hve geltinous texture nd typicl white colour. After 54 d of feed deprivtion, 7 of 60 fillets were evluted to be strongly ffected by feed deprivtion; however, only 3 of these hd both defects simultneously. On the lst smpling, 34 of 60 fillets were ssessed ffected with 21 fillets hving both geltinous texture nd typicl white colour. It my be questioned whether the geltinous texture nd typicl white colour is solely due to feed deprivtion or lso due to spwning, since the fish in the experiment were spwning during the first 54 d of live-storge (Ageev et l., 2017). However, other scientists experienced tht long-term feed-deprived Atlntic cod cn hve fillets with chrcteristic geltinous or sloppy texture nd typicl white colour (Love, 1988; Sæther et l., 2016). Sæther et l. (2016) studied qulity chnges during live-storge of immture cod cught during n intensive feeding seson. They lso observed incresing number of the fish with geltinous texture nd typicl white colour s the period of feed deprivtion incresed. 13

14 4. Conclusion The results demonstrted tht prolonged feed deprivtion nd time of filleting of mture livestored Atlntic cod ffect both biochemicl nd sensory spects of the muscle. Feed deprivtion resulted in fillets hving higher wter content, unplesntly soft texture, typicl white colour nd less fresh se odour. These chnges in product qulity occurred minly fter 54 d of feed deprivtion. The til products were more prone to contrction nd hd higher drip loss thn loins nd whole fillets independently of the period of feed deprivtion nd time of filleting. 14

15 Acknowledgements The work is prt of project CATCH: Mrket-oriented nd sustinble vlue chins for cod products bsed on live-storge, nd ws supported by the Reserch Council of Norwy (No /E50). We would like to thnk the stff t Nofim AS deprtment Sefood qulity, Tromsø, for their gret contribution to the study. 15

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17 Jørpelnd, G., Imslnd, A., Stien, L. H., Bleie, H., & Roth, B. (2015). Effects of filleting method, stress, storge nd seson on the qulity of frmed Atlntic cod (Gdus morhu L.). Aquculture Reserch, 46, Kiessling, A., Bjørnevik, M., Thomssen, M., Rør, M. B., Mørkøre, T., Roth, B., Erikson, U., & Jordheim, O. (2007). From Cge to Tble. In M. Thomssen, R. Gudding, B. Norberg & L. Jørgensen (Eds.), Aquculture Reserch: From Cge to Tble (pp ). Oslo, Norwy: The Reserch Council of Norwy. Kristoffersen, S., Tobissen, T., Esissen, M., Olsson, G. B., Godvik, L. A., Seppol, M. A., & Olsen, R. L. (2006). Effects of pre rigor filleting on qulity spects of Atlntic cod (Gdus morhu L.). Aquculture Reserch, 37, Kristoffersen, S., Vng, B., Lrsen, R., & Olsen, R. L. (2007). Pre-rigor filleting nd drip loss from fillets of frmed Atlntic cod (Gdus morhu L.). Aquculture Reserch, 38, Love, R., Robertson, I., Smith, G., & Whittle, K. (1974). The texture of cod muscle. Journl of Texture studies, 5, Love, R. M. (1988). The Food Fishes: Their intrinsic vrition nd prcticl implictions. London, Englnd: Frrnd Press. Michie, I. (2001). Cuses of downgrding in the slmon frming industry. In S. C. Kestin & P. D. Wrris (Eds.), Frmed fish qulity (pp ). Oxford: Fishing New Books - Blckwell Science. Misimi, E., Erikson, U., Digre, H., Skvhug, A., & Mthissen, J. (2008). Computer Vision- Bsed Evlution of Pre- nd Postrigor Chnges in Size nd Shpe of Atlntic Cod (Gdus morhu) nd Atlntic Slmon (Slmo slr) Fillets during Rigor Mortis nd Ice Storge: Effects of Perimortem Hndling Stress. Journl of Food Science, 73, E57-E68. Mørkøre, T., Thirovic, V., & Einen, O. (2008). Impct of strvtion nd hndling stress on rigor development nd qulity of Atlntic slmon (Slmon slr L). Aquculture, 277, Offer, G., & Trinick, J. (1983). On the mechnism of wter holding in met: the swelling nd shrinking of myofibrils. Met Science, 8, Olsson, G. B., Gundersen, B., & Esissen, M. (2006). Pre-slughter strvtion of frmed Atlntic cod fed vegetble proteins: effects on qulity prmeters. In J. B. Luten, C. Jcobsen, K. Bekert, A. Sæbø & J. Oehlenschläger (Eds.), Sefood reserch from fish to dish. Qulity, sfety nd processing of wild nd frmed fish (pp ). The Netherlnds: Wgeningen Acdemic Publishers. Stien, L. H., Suontm, J., & Kiessling, A. (2006). Imge nlysis s tool to quntify rigor contrction in pre-rigor-filleted fillets. Computers nd electronics in griculture, 50, Sæther, B. S., Noble, C., Midling, K. Ø., Tobissen, T., Akse, L., Koren, C., & Humborstd, O. B. (2016). Velferd hos villfnget torsk i merd - Hovedvekt på hold uten fôring ut over 12 uker Rpport (Vol. 16/2016). Tromsø, Norwy: Nofim [in Norwegin]. The Norwegin Fishermen's Sles Orgniztion. (2016). For kystens verdier. Årsberetning Tromsø. 17

18 Figure legends Fig. 1. Score plot nd correltion loding plot of the PCA-model of qulity differences between the fish exposed to feed deprivtion for 2, 26, 54 or 82 d. PCA-1 nd PC-2 explined 33% nd 21% of totl vrition in the dt, respectively. The outer nd inner ellipses indicte 100% nd 50% of explined vrince, respectively. Gel texture, geltinous texture, Atypicl colour, typicl white colour re close to ech other in the lodings plot. Fig. 2. Averge contrction (% of initil product length) nd drip loss (% of initil product weight) in loins ( ) nd tils ( ) mde 4, 6, 10, 14, 24 nd 48 h fter slughter of Atlntic cod exposed to feed deprivtion for 26 d (solid line), 54 d (dshed line) nd 82 d (dotted line) fter ctch. All products were stored t 0 o C until dy 7 post mortem. Lower cse letters indicte differences (p < 0.05) between time of filleting for either loins or tils, nd sterisks ( = p < 0.05) show significnt differences from the other two smpling dys. In ddition, the contrction of tils (B) produced 4 h post mortem from cod feed deprived for 26 d ws significntly higher those produced fter 82 d but not fter 54 d of feed deprivtion (not shown in Fig.). Fig. 3. Muscle hrdness (N) nd wter content (%) mesured 7 d post mortem on whole cod fillets mde 4, 6, 10, 14, 24 nd 48 h post mortem. The fish were strved for 54 (dshed line, muscle hrdness:, Wter: ) nd 82 (dotted line, muscle hrdness:, Wter: ) d fter cpture. Lower cse letters show significnt differences (p < 0.05) between time of filleting (h) t ech smpling dy, nd sterisk ( = p < 0.05) indicte the significnt differences t sme time of filleting for fillets produced on dy 54 nd dy

19 Tble 1. Vribles with significnt impct on qulity ttributes. The effect is shown bsed on weighted regression coefficient (Rw). Significnce is identified by Mrtens uncertinty test (p < 0.05). PLS nlysis, Y, muscle ph, MH (muscle hrdness), contrction, drip loss, wter content, fillet index (odour, gping, colour, texture), geltinous texture nd berrnt colour, X-mtrix, length, gutted weight, strvtion nd time for fileting. Qulity Vribles with significnt effect on qulity ttributes ttributes of fillet Rw Muscle ph Length Gutted weight MH Length Gutted weight Feed deprivtion Time of filleting Contrction Time of filleting Drip loss Length Gutted weight Time of filleting Wter content Feed deprivtion Filet index Geltinous texture Atypicl white colour Time of filleting Length Gutted weight Feed deprivtion Time of filleting Odour Feed deprivtion Surfce None Gping Length Gutted weight Time of filleting Colour Gutted weight Feed deprivtion Texture Feed deprivtion Time of filleting Gutted weight Feed deprivtion Time of filleting Gutted weight Feed deprivtion Time of filleting

20 Fig

21 Drip loss [%] Contrction [%] b b b c A) c c d b b b c c c B) c c c 6,0 5,0 4,0 C) b b D) 3,0 b b b b 2,0 1,0 b b b b b b 0,0 Fig Time of filleting [h] Time of filleting [h] 21

22 Muscle hrdness [N] Wter content [%] 5,0 4,5 4,0 3,5 b b b b b b 85,0 84,5 84,0 83,5 3,0 2,5 b b b b 83,0 82,5 2,0 82,0 1,5 1,0 0,5 0,0 b b 81,5 81,0 80,5 b 80, Time of filleting [h] Fig

23 Supplementry Mteril: Appendix A Tble A.1 Sttisticl chrcteristics for contrction nd drip loss mesured on dy 7 post mortem in loins nd tils obtined from cod feed-deprived for 26, 54 or 82 d fter cpture. The products were mde on time spns 4, 6, 10, 14, 24 or 48 h post mortem. The sttisticl differences (p < 0.05) between loins nd tils within sme smpling dy nd time for filleting (h) re given s t-sttistic nd p-vlue under Between loins nd tils. The differences between times of filleting (h) within sme smpling dy for ech product re specified using F- nd p vlues for Between times of filleting (h) within sme smpling dy. Time of filleting (h) Loins Tils Contrction Between loins nd tils Drip loss 26 d 54 d 82 d 26 d 54 d 82 d t(18) = , p = t(18) = , p = t(17) = , p = t(18) = , p = t(18) = 0.501, p = t(18) = , p = F(5,54) = ; p = F(5,53) = ; p = t(18) = , p = t(18) = , p = t(18) = , p = t(18) = , p = t(18) = , t(18) = , t(18) = , t(18) = , p = p = p = p = t(18) = , t(18) = , t(17) = , t(18) = , p = p = p = p = t(18) = 2.811, t(18) = 0.140, t(18) = , t(18) = , p = p = p = p = t(18) = 2.288, t(17) = 0.354, t(18) = , t(18) = , p = p = p = p = t(18) = , t(17) = , t(18) = , t(18) = , p = p = p = p = Between times of filleting (h) within sme smpling dy F(5,54) = ; F(5,52) = ; F(5,52) = 6.087; F(5,53) = 1.344; p = p = p = p = F(5,53) = ; F(5,54) = ; F(5,53) = 1.433; F(5,53) = ; p = p = p = p = t(18) = , p = t(18) = , p = t(18) = , p = t(18) = , p = t(17) = , p = t(17) = , p = F(5,52) = 1.741; p = F(5,54) = 3.357; p =

24 Tble A.2 Contrction (Rnge, %) detected on dy 7 post slughter in loin nd tils produced t the sme time (h) but on different smplings, 26, 54 or 82 d fter cpture. The sttisticl differences (p < 0.05) re given s F-sttistic nd p-vlue. Time of filleting (h) Between smplings 26 d, 54 d nd 82 d fter cpture Contrction Loins 82 d 26 d 54 d Rnge Sttisticl differences Rnge Rnge (%) (%) (%) Tils 26 d Rnge (%) 54 d Rnge (%) 82 d Rnge (%) Sttisticl differences F (27) = 0.163, p = F (27) = 3.485, p = F (27) = 0.439, p = F (27) = 1.067, p = F (27) = 2.578, p = F (26) = 7.470, p = F (27) = 8.918, p = F (27) = 2.875, p = F (26) = 6.681, p = F (26) = 9.371, p = F (26) = 6.940, p = F (27) = 9.371, p =

25 Tble A.3 Drip loss (Rnge, %) detected on dy 7 post slughter in loin nd tils produced t the sme time (h) but on different smplings, 26, 54 or 82 d fter cpture. The sttisticl differences (p < 0.05) re given s F-sttistic nd p-vlue. Time of filleting (h) Between smplings Drip loss Loins Tils 26 d Rnge 54 d Rnge 82 d Rnge Sttisticl differences 26 d Rnge 54 d Rnge 82 d Rnge Sttisticl differences (%) (%) (%) (%) (%) (%) F (27) = 0.062, p = F (27) = 2.690, p = F (27) = 1.542, p = F (27) = 0.155, p = F (27) = 2.283, p = F (27) = 3.486, p = F (27) = 0.877, p = F (27) = 1.843, p = F (26) = 0.058, p = F (27) = 1.868, p = F (26) = 0.058, p = F (27) = 3.593, p =

26 Tble A.4 Sttisticl chrcteristics for muscle hrdness (N) nd wter content (%) mesured on dy 7 post mortem in fillets mde 4, 6, 10, 14, 24 or 48 h post slughter of Atlntic cod exposed to feed deprivtion for 54 or 82 d fter cpture. The sttisticl differences (p < 0.05) between smpling dys but within the sme time of filleting (h) re given s t-sttistic nd p-vlue, nd between times of filleting (h) within the sme smpling dy re given s F-sttistic nd p vlue. Between smpling dys 54 nd 82 fter cpture Filleting (h) Muscle hrdness (N) Wter content (%) 4 t(18.000) = 2.402, p = t(10.000) = , p = t(18.000) = 1.173, p = t(10.000) = , p = t(18.000) = , p = t(10.000) = , p = t(17.000) = 2.590, p = t(10.000) = , p = t(18.000) = 2.116, p = t(10.000) = , p = t(18.000) = 2.540, p = t(10.000) = , p = Between filleting hours within sme smpling dy 54 d F(5,53) = 1.324; p = F(5,30) = 3.177; p = d F(5,53) = 5.712; p = F(5,30) = 4.312; p =