Organic and Conventional Chicken Meat Produced In Uruguay: Colour, Ph, Fatty Acids Composition and Oxidative Status

Transcription

1 Americn Journl of Food nd Nutrition, 213, Vol. 1, No. 2, Aville online t Science nd Eduction Pulishing DOI: /jfn Orgnic nd Conventionl Chicken Met Produced In Uruguy: Colour, Ph, Ftty Acids Composition nd Oxidtive Sttus G. Cstromán 1, M. del Puerto 2, A. Rmos 1,2, M.C. Crer 1,2, A. Sdoun 1,* 1 Fisiologí y Nutrición, Fcultd de Ciencis, Universidd de l Repúlic. Iguá. Montevideo, Uruguy 2 Dpto. Producción Animl y Psturs, Lortorio de Clidd de Alimentos y Clidd de Productos, Fcultd de Agronomí, Universidd de l Repúlic. Eugenio Grzón 89. Montevideo, Uruguy *Corresponding uthor: sdoun@fcien.edu.uy Received April 2, 213; Revised July 16, 213; Accepted July 18, 213 Astrct The orgnic chicken met is present in the mrket nd ccepted y consumers in Uruguy. However, no informtion out its qulity is ville. The study of orgnic met showed higher lightness (L*) nd lower yellowness (*) thn conventionl chicken met. For redness (*), the results were inconclusive. Hem iron content ws higher in orgnic met nd the lipids content ws not different etween orgnic nd conventionl met. The ftty cids composition showed tht the orgnic met presented %, % nd % of sturted, monounsturted nd polyunsturted ftty cids (PUFA), respectively. The limited uses of corn nd soyen to fed orgnic chickens, proly explin the unexpected low level of PUFA in orgnic met. The orgnic met lso showed lower TBARs level nd similr level of protein cronyl in comprison to the conventionl one. Ctlse presented higher ctivity in orgnic met compred to the conventionl one. No differences were oserved for superoxide dismutse nd glutthione peroxidse. Keywords: orgnic met, roiler met, ftty cids, TBARs, SOD, GPx, ctlse Cite This Article: Cstromán, G., M. del Puerto, A. Rmos, M.C. Crer, nd A. Sdoun, Orgnic nd Conventionl Chicken Met Produced In Uruguy: Colour, Ph, Ftty Acids Composition nd Oxidtive Sttus. Americn Journl of Food nd Nutrition 1, no. 2 (213): doi: /jfn Introduction The glol tendency towrds the consumption of differentited poultry products hs een growing stedily in the pst yers in Europe nd the United Sttes [1], with consequent increse of the use of lterntive poultry production systems such s the Lel Rouge [2,3,4,5]. In Uruguy, consumers show growing preference for met from roilers rered under orgnic conditions, which is relted to the perception of this met s one produced in n environment friendly system tht considers niml welfre nd produces met with good flvour nd high nutritionl levels [4,6]. Consequently, orgnic frms hve een developed loclly y poultry reeders to produce orgnic chicken for the Uruguyn mrket using stndrd fst-growing reeds [7]. These poultry reeders were prt of the APODU [8], n ssocition which groups ll the niml nd vegetl orgnic producers of the country. The memers of this ssocition must follow determined rules to produce orgnic products on governmentl regultion [9]. The orgnic rering system is generlly reputed to reduce stress, increse welfre nd comfort for irds [1]. This rering system seems to e lso ssocited with n improving sensory qulity nd enhncing the flvour of met, s reported y Cstellini [4] nd Fntico et l [11]. However, the orgnic chicken met seems to generlly hve higher level of oxidtion expressed y TBARS indices in comprison to the conventionl met [4]. The oxidtive processes re the most importnt non-microil fctors responsile for met deteriortion resulting in losses of oth nutritionl vlue nd food qulity. This leds to dverse chnges in sensory properties such s ppernce, texture nd flvour, nd possile production of toxic compounds. [12,13,14,15,16]. Fortuntely, the presence of nturlly occurring ntioxidnt sustnces in chickens met scvenge free rdicls, such s the ntioxidnt enzymes superoxide dismutse (SOD), ctlse nd glutthione peroxidise (GPX), counterlnces the negtive effect of oxidtion. In this investigtion, two commercil products consisting of orgnic nd conventionl chicken met, oth ville in the mrket of Uruguy, were evluted. The study compred some met qulity prmeters such s met colour, ph, hem iron content, totl lipids, ftty cids composition, TBARs, protein cronyls, SOD, CAT nd GPx ctivities. 2. Mterils nd Methods

2 Americn Journl of Food nd Nutrition Animls nd Smples Five crcsses from n orgnic system nd five from conventionl one were otined from locl roker in Montevideo (Uruguy). The ten crcsses (weight of pproximtely 2g nd 25g for the orgnic nd the conventionl chicken, respectively) were trnsported to the lortory in refrigerted isotherm ox nd the left Pectorlis mjor, Srtorius nd Gstrocnemius muscles were excised nd used for immedite study of colour, ph t 3 nd 24h post-mortem, nd the hem iron content t 24h post-mortem. The right Pectorlis mjor, nd Gstrocnemius muscles were lso entirely excised, rpidly frozen t 2ºC nd stored t this sme temperture in seled g until eing nlysed for lipids, ftty cids composition, TBARS, Protein cronyls, nd enzymes ctivities Determintions of Colour nd ph The color prmeters (L*, *, *) were mesured in Pectorlis mjor, Srtorius nd Gstrocnemius muscles using colorimeter Minolt CR-1, sed on the Ciel Colour System [17]. The ph t 3h post-mortem nd the ultimte ph (t 24 h post-mortem) were mesured in the sme three muscles with digitl ph-meter LTlutron PH- 21 (with utomtic temperture compenstion) equipped with penetrting sper tip ph electrode (Model: PE- 4HD) Determintion of Hem Iron Content Hem iron content ws determined s hemin, fter extrction with cidified cetone solution, s previously descried [18,19,2]. Hemin ws quntified in Genesys 6-UV spectrophotometer (Thermo Corportion, USA) t 64nm. Met smples (1g) were finely chopped nd mcerted in 4.5ml of cidified cetone (cetone: HCl: wter - 9:2:8) in glss tues for 1 minute on reduced light to minimize the pigment fding during the extrction. The tues were seled to reduce evportion nd held for incution t room temperture (2-22ºC) in the drkness for 1h. After incution, the tue content ws filtered from glss filter ppers (Whtmn GFA) nd the sornce of the filtrte ws red t 64 nm. The hem iron content ws clculted using the fctor.882μg iron / μg hemtin [18]. All smples were nlyzed in duplicte Determintion of Totl Lipid Content Lipids were extrcted y homogeneiztion of 2.5 g smples of wet Pectorlis mjor nd Gstrocnemius muscles using n Ultr Turrx (IKA T18 Bsic), t 26 rpm, with 5 ml of 2:1 Chloroform:Methnol solvent mixture [21]. The extrction solution ws decnted overnight nd the chloroform phse ws eliminted y roto-evportion. The lipids were weighted ccurtely t.1mg. The results were expressed s % of totl lipids for ech smple. All smples were nlyzed in duplicte Ftty Acid Quntifiction Ech smple of extrcted lipids, pproximtely 4 mg, ws converted to methyl esters [22]. The lipids were dissolved in 2ml of hexne nd 4 ml of 2 M KOH in methnol were dded. The mixture ws vortexed for two minutes, centrifuged t 1 g for 1 minutes t 4ºC, nd the hexne phse, which contins the methylted ftty cids, ws seprted to e injected in the chromtogrph. The ftty cid composition of ech smple ws determined twice y gs chromtogrphy using Clrus 5 Gs Chromtogrpher (Perkin Elmer Instruments) equipped with FID detector. The column ws 1m CPsil-88 (Vrin, Netherlnd) nd the temperture progrm ws 1 min t 9ºC, to 18ºC (rte 3ºC y min) nd mintined for 2 min. After tht, the temperture ws rised to 22ºC (rte of 2ºC y min) nd mintined for 1 min. One µl smple ws injected y n utosmpler (Perkin Elmer, USA) using the split method with vlve opening t 3sec post-injection. A fixed vented flow of 5% ws determined to drin the solvent excess. The crrier gs ws H 2 ( %) t flow rte of 2ml/min, The FID flme ws mintined y H 2 nd ir t flow rte of 45ml/min nd 35ml/min, respectively. The clirtion nd the pek determintions were sed on uthentic stndrds ftty cids from Sigm-Aldrich (St Louis USA). The results were expressed for ech ftty cid s g/ 1 g totl detected ftty cids Determintion of Lipid nd Protein Oxidtion Lipid oxidtion ws determined y the method of Lynch nd Frei [23] with some modifictions. Smples of 1.5g were homogenized with the extrction uffer (.15 M KCl,.2 M EDTA nd.3 M BHT) using n Ultr Turrx (IKA T18 Bsic) t 12 rpm for 1min. Two ssy tues contining 4ml of the homogente were frozen t -2ºC for further use in protein cronyls ssy nd determintion of protein content. The sme procedure without dding the smple ws followed for the lnk. Four ml of the homogente were centrifuged t 2 g for 1min t 4ºC nd 1 ml of the superntnt ws incuted with 1 ml of TBA-TCA solution (35 mm TBA nd 1 % TCA in 125mM HCl), in oiling wter th for 3min. Afterwrds, the ssy tues were cooled in ice for 5min nd kept t room temperture for nother 45 min. Two ml of n-utnol ws dded nd, fter centrifugtion t 3 g for 1 min, the superntnt ws extrcted nd its sornce ws mesured t 535 nm. MDA concentrtion ws clculted using the molr extinction coefficient of MDA (156, M -1 cm -1 ). Results were expressed s mg of MDA per kg of fresh met. Protein oxidtion level ws ssyed using method previously descried [24]. The frozen smples seprted the dy prior to TBARS ssys were thwed nd let stnd for 15min t room temperture nd finlly vortexed for 1 seconds. Two 2ml liquots of the smples were put in different glss tues (smple nd corresponding lnk), kept in ice nd fterwrds centrifuged t 3 g for 1 min t 4ºC. Two ml of 2M HCl nd 2ml of DNPH solution (2 mm DNPH in 2M HCl) were dded to the lnk nd smple tues, respectively. These tues were incuted t room temperture for 1 h, vortexed 5 seconds every 1min; then 2ml of 2 % TCA were dded to ll the tues. Those tues were kept t room temperture for nother 15min nd vortexed for 5 seconds every 5min. These tues were then centrifugted t 2g for 1min. Pellets were wshed three times with 4ml of ethnol:ethyl cette (1:1), centrifuged ech time, to eliminte trces of

3 14 Americn Journl of Food nd Nutrition DNPH. Then, pellets were dissolved with 6ml of 6M gunidine HCl with 2 mm KH 2 PO 4, incuting t room temperture for 15 min nd vortexed for 5 seconds every 5 min. Afterwrds they were centrifuged t 24 g for 1 min nd the sornce of the superntnt ws mesured t 37 nm. The concentrtion of the DNPH ws clculted using the DNPH molr extinction coefficient (22 M -1 cm -1 ). Results were expressed s nm of DNPH per mg of protein Superoxide Dismutse nd Ctlse Activities An unique smple extrction ws mde for oth enzymes ctivity mesurements. Smples of g frozen met were homogenized with 26 ml of extrction uffer (.15 M KCl nd.79 M EDTA ph 7.4), using n Ultr Turrx (IKA T18 Bsic) t 12 rpm for 1 min. The homogente ws centrifuged 1 min t 9 g t 4 ºC. The superntnt ws extrcted nd used to determine SOD nd ctlse ctivities. For the totl SOD ctivity determintion, the incution mixture ws prepred s follows: 285µl of 5mM phosphte uffer (ph 8.2), 75µl of superntnt nd 75µl of 1mM pyrogllol. This method is sed on the inhiition of pyrogllol utooxidtion y SOD, nd is showed y the increse in sornce t 34 nm recorded on 1 seconds intervls during 2 minutes. The results re expressed s IU nd IU per grm of fresh met. An IU ws defined s the SOD ctivity needed to inhiit 5 % of pyrogllol uto-oxidtion [25,26]. Ctlse ctivity determintion ws done using the method descried y Aei [27]. It mesures the disppernce of H 2 O 2 reflected y the decrese in the sornce t 24 nm during period of 21 s recorded every 3 s. The incution mixture contined: 282 µl of extrction uffer, 9 µl of the ove mentioned superntnt nd 9 µl of 6.56 mm H 2 O 2. Results were expressed s µmoles H 2 O 2 min -1 per grm of fresh met nd s nm H 2 O 2 min -1 per mg of protein Glutthione Peroxidse Activity The method followed for this determintion ws previously descried [28,29]. Smples of 5g frozen met were homogenized with 25ml of extrction uffer (5 mm KH 2 PO 4 nd.5mm EDTA), using n Ultr Turrx (IKA T18 Bsic) t 18 rpm for 1 min. The homogente ws centrifuged t 2g for 2min t 4ºC nd the superntnt ws filtered. A supplementry liquot of 4 ml ws sved t 4ºC for further protein determintion ssy. The composition of the ssy mixture ws 5 mm KH 2 PO 4 uffer,.5mm EDTA, 1mM reduced glutthione (SIGMA-ALDRICH G4251),.15 mm NADPH (SIGMA N163 or Fluk 9322), 1.5 U glutthione reductse (SIGMA G3664),.15 mm H 2 O 2 nd 1mM NN 3 (SIGMA S-22). The incution mixture ws prepred s follows: 198µl of ssy mixture nd 2µl of filtered smple. Glutthione oxidse ctivity ws mesured t 22ºC, sed on the recording of oxidtion of NADPH reflected y the diminution of sornce t 34 nm of the incution mixture every 3sec through period of 3min. Glutthione peroxidse ctivity ws expressed s µmoles of oxidized NADPH min -1 per grm of fresh met nd s nm min -1 per mg of protein. The concentrtion of the NADPH ws clculted using the NADPH molr extinction coefficient t 22ºC (63 M -1 cm -1 ) Determintion of Protein Content Assessment of protein content for enzymes ctivities determintion ws done using the method descried y Stoscheck [3]. BSA (SIGMA) used s stndrd, ws dissolved in the corresponding ssy uffer. Asornce were mesured t 28 nm with the use of spectrophotometer Genesys 6 (Thermo, USA) nd using qurtz cells Sttisticl Anlysis Dt were nlyzed using NCSS (NCSS, 329 North 1 Est, Kysville, UT 8437, USA) softwre, running the GLM procedure followed y the Tukey-Krmer multiple comprison test. All dt within the sme vrile, from ech production system were compred using one-wy ANOVA procedure. The significnce level ws estlished t p <.5. All vlues re reported s men ± stndrd error of the men (SEM). 3. Results 3.1. Colour nd ph The colour determintion showed for lightness (L*) system min effect (p <.1), muscles min effect (p <.1) nd time effect (p <.5). The orgnic chicken met showed higher L* thn the conventionl one. Within the sme muscle nd time, t 3 nd 24 hours postmortem the Pectorlis mjor nd Gstrocnemius muscles of orgnic chickens showed higher L* thn the Srtorius muscle. For conventionl chicken met, t 3 hours postmortem the L* showed tht Gstrocnemius > Pectorlis mjor > Srtorius (Tle 1). At 24 hours post-mortem, the L* of the Srtorius muscle showed tht Gstrocnemius = Pectorlis mjor > Srtorius (Tle 1). For the redness (*), the results showed system (p <.1) nd muscle (p <.1) min effect, ut not time effect. At 3 ut not t 24 hours post-mortem, the orgnic chicken met showed higher * thn the conventionl ones (Tle 1). Within the sme muscle nd time, the * showed for orgnic met tht t 3 hours postmortem Srtorius > Gstrocnemius > Pectorlis mjor (Tle 1). The conventionl chicken showed * results s follow Gstrocnemius = Srtorius > Pectorlis mjor. At 24 hours post-mortem the * in orgnic chicken met showed tht Srtorius > Pectorlis mjor = Gstrocnemius. For conventionl ones, the results for * showed differences s follow Gstrocnemius > Pectorlis mjor = Srtorius (Tle 1). For yellowness (*), the results showed system (p <.1) nd time (p <.1) min effects, ut not muscle effect (Tle 1). The vlues of * were lower in orgnic met thn in conventionl met, oth t 3 nd 24 hours post-mortem. Independently to the production system nd muscles, the vlue of * were lower t 3 thn t 24 hours post-mortem. Within the sme muscle nd time, no difference etween the three muscles ws detected (Tle 1).

4 Americn Journl of Food nd Nutrition 15 Tle 1. Color of met t 3 hours nd 24 hours post mortem in three muscles of orgnic nd conventionl chicken Hours post-mortem 3 24 Muscles Orgnic Conventionl Orgnic Conventionl L* Pectorlis mjor 55.5 ± ± ± ±.6ª Srtorius 51.3 ± ±.78c 53.1 ± ±.4 Gstrocnemius 56.2 ± ± ± ±.4 Significtion Min effects System : Muscles : Time : * Pectorlis mjor 1.38 ±.24c.74 ± ± ±.26 Srtorius 4.34 ± ± ± ±.21 Gstrocnemius 2.93 ± ± ± ±.4ª Significtion Min effects System : Muscles : Time : NS * Pectorlis mjor 15.1 ± ± ± ±.5 Srtorius 15.3 ± ± ± ±.6ª Gstrocnemius 14.6 ± ± ± ±.8 Significtion Min effects System : Muscles : NS Time : Vlues re mens (n=5) ± SEM. L*= lightness, *= redness, *= yellowness. Min effects significtion: *= p <.5. ***= p <.1, NS= not significnt. Within the sme production system nd time pos-mortem, different letters mens significnt differences (p <.5). The ph showed system min effect (p <.1) ut not muscle nor time effect. The ph ws higher t 3 nd 24 hours in the chicken met of conventionl system in comprison to the chicken met of orgnic system (Tle 2). Tle 2. Vlues of met ph t 3 hours nd 24 hours (ultimte ph) post-mortem in three muscles of orgnic nd conventionl chicken. Hours post-mortem 3 24 Muscles Orgnic Conventionl Orgnic Conventionl Pectorlis mjor 6.3 ± ± ± ±.5 Srtorius 6.12 ± ± ± ±.3 Gstrocnemius 6. ± ± ± ±.3 Significtion Min effects System Muscle NS Time NS Vlues re mens (n=5) ± SEM. Min effects significtion: ****= p <.1, NS=not significnt Hem Iron Content The results for hem iron content showed system (p <.1) nd muscle (p <.1) min effect (Figure 1). Within the sme production system, oth in orgnic nd conventionl chicken met, Pectorlis mjor showed lower (p <.5) content of hem iron in comprison to Srtorius nd Gstrocnemius muscles (Figure 1) Lipid nd Ftty Acid Composition The lipid content showed muscle min effect (p <.2) ut not system min effect (Figure 2). However, independently of the production system, the Gstrocnemius muscle showed more lipids (p <.5) thn the Pectorlis mjor muscle (Figure 2). mg / kg wet met Pectorlis mjor Srtorius Gstrocnemius Totl lipids (%) Pectorlis mjor Gstrocnemius Orgnic Conventionl Min effects: System NS ; Muscle p <.2 Orgnic Conventionl Min effects: System p <.1 ; Muscles p <.1 Figure 1. Hem iron determined t 24 hours post mortem in three muscles of chickens produced on orgnic nd conventionl rering system. Brs re men ± SEM (n=5). Different letters t the top of the rs mens significnt differences (p <.5) Figure 2. Totl lipids content in two muscles of chickens produced on orgnic nd conventionl rering system. Brs re men ± SEM (n=5). Different letters t the top of the rs mens significnt differences (p <.5). NS= not significnt For ftty cids composition, min effect for the production system hs een otined for lmost ll the

5 16 Americn Journl of Food nd Nutrition detected ftty cids, except C16:, C18:3n6 nd C2:5n3 (Tle 3). A muscles min effect hs een oserved only for C16:, C16:1, C18:, C18:3n3 nd C2:3n6 (Tle 3). When the different clsses of ftty cids were considered, it ppers tht the orgnic chicken met showed higher (p <.1) content of monounsturted ftty cids nd lower (p <.1) content of polyunsturted ftty cids (Tle 3). Furthermore, the n-6 nd the n-3 ftty cids fmily oth showed lower (p <.1) contents in orgnic chicken met (Tle 3). No effect of production system ws detected for the sturted ftty cids. This lst clss of ftty cids, showed only muscle min effect (p <.1), hving the Gstrocnemius muscle more sturted ftty cids thn the Pectorlis mjor one (Tle 3). Tle 3. Ftty cids composition of met in two muscles of chickens produced on orgnic nd conventionl rering system Ftty cids Orgnic Rering system Min effects Conventionl significtion (g/1 g Ftty cids ) Pectorlis mjor Gstrocnemius Pectorlis mjor Gstrocnemius System Muscles C14: 1.9 ±.9.95 ±.8.46 ±.3.33 ±.5 *** NS C14:1.23 ±.3.16 ±.7.8 ±.1.5 ±.2 *** NS C16: 21.45± ± ± ±.79 NS * C16: ± ± ± ±.21 *** ** C18: 9.29 ± ± ± ±.96 * * C18: ± ± ± ±1.63 *** NS C18:2n ± ± ± ±1.94 *** NS C2:.5±.3.4 ±.1.8±.6.9 ±.2 *** NS C18:3n6.7 ±.1.6 ±.9.12 ±.1.8 ±.2 NS NS C2:1.82 ± ±.4.23 ±.3.17 ±.2 *** NS C18:3n3.47 ±.6.36 ±.5 2. ± ±.26 *** ** C2:3n6.7 ±.1.15 ±.3.35 ±.4.66 ±.11 *** ** C2:3n3.54 ± ±.13 nd nd *** NS C2:4n ± ± ± ±1.2 ** NS C2 :5n3.9 ±.3.13 ±.3.14 ±.2.25 ±.8 NS NS C22:4n6.26 ±.7.33 ±.1.45 ± ±.18 * NS C22 :5n3.29 ±.7.17 ±.5.45 ±.9.96 ±.25 *** NS C22 :6n3.16 ±.5.3 ±.7.77 ± ±.53 *** NS Unidentified 2.45 ± ± ± ±.21 *** NS SFA 31.88± ± ± ±1.51 NS ** MUFA 53.16± ± ± ±1.85 *** NS PUFA 12.49± ± ± ±1.58 *** NS n ± ± ± ±1.31 *** NS n ± ± ± ±.65 *** NS Vlues re mens ± S.E.M (n=5), nd= not detected, SFA= Sturted ftty cids, MUFA= Monounsturted ftty cids, PUFA= Polyunsturted ftty cids. Min effects significtion: *= p <.5, **= p <.1, ***= p <.1, NS= not significnt Lipid nd Protein Oxidtion For TBARS the results showed system (p <.1) min effect ut not muscle min effect. The orgnic chicken met presented lower TBARS level thn the conventionl one (Figure 3). For protein cronyls, neither system nor muscle min effect ws oserved (Figure 4). mm DNPH / mg protein Pectorlis mjor Gstrocnemius Pectorlils mjor Gstrocnemius.5 mg MDA / kg wet met Orgnic Conventionl Min effects: System p <.1 ; Muscle NS Figure 3. TBARS in two muscles of chickens produced on orgnic nd conventionl rering system. Brs re men ± SEM (n=5). NS= not significnt. Orgnic Conventionl Min effects: System NS ; Muscle NS Figure 4. Protein cronyls content in muscles of chickens produced on orgnic nd conventionl rering system. Brs re men ± SEM (n=5). NS= not significnt 3.5. Anti-oxidtive Enzyme Activities The superoxide dismutse ctivity expressed oth s U/g wet met nd U, showed neither system effect nor muscle effect (Figure 5). The ctlse ctivity expressed y g of wet met showed system (p <.2) nd muscle (p <.1) min effect (Figure 6). Also, when ctlse ctivity ws

6 Americn Journl of Food nd Nutrition 17 expressed y mg of protein, the results showed system (p <.1) nd muscle (p <.1) min effect (Figure 6). In ll cses, the orgnic chicken showed more ctlse thn the conventionl ones. Furthermore, the Pectorlis mjor muscle showed lower ctivity of ctlse (p <.5) thn Gstrocnemius muscle in oth production systems (Figure 6). U /g wet met Orgnic Conventionl Min effects: System NS ; Muscle NS Pectorlis mjor Gstrocnemius Orgnic Conventionl Min effects: System NS ; Muscle NS Figure 5. SOD ctivity in two muscles of chickens produced on orgnic nd conventionl rering system. Brs re men ± SEM (n=5). NS= not significnt mm H 2 O 2 / min / g wet met 14 Pectorlis mjor Gstrocnemius Orgnic Conventionl Orgnic Conventionl Min effects: System p <.2 ; Muscle p <.1 Min effects: System p <.1 ; Muscle p <.1 Figure 6. Ctlse ctivity in muscles of chickens produced on orgnic nd conventionl rering system. Brs re men ± SEM (n=5). Different letters t the top of the rs mens significnt differences (p <.5) mm NADPH / min /g wet met Orgnic Conventionl Min effects: System p <.2 ; Muscle p <.5 Pectorlis mjor Gstrocnemius Orgnic Conventionl Min effects: System NS; Muscle p <.1 Figure 7. GPx ctivity in muscles of chickens produced on orgnic nd conventionl rering system. Brs re men ± SEM (n=5). Different letters t the top of the rs mens significnt differences (p <.5). NS= not significnt The GPx ctivity expressed y g of wet met showed oth min effect of the production system (p <.2) nd muscle (p <.5) min effect (Figure 7). When the results were expressed y mg of protein only muscle (p <.1) min effect ws oserved, ut not production system effect (Figure 7). However, oth in orgnic nd conventionl production system, the Pectorlis mjor muscle showed lower (p <.5) ctivity of GPx thn Gstrocnemius muscle (Figure 7) nm NADPH / min / mg protein U nm H 2 O 2 /min / mg protein 4. Discussion In Uruguy, chicken met is well ccepted y consumers nd tkes gret prt of the regime t ll ges. The positive helthy imge of the chicken met, oth orgnic nd conventionl, is ssocited principlly with its nutritionl composition relted to its lower ft content nd the presence of polyunsturted ftty cids (PUFA). The ffordle price of this kind of met in the mrket mkes it very ttrctive. The poultry mrket in Uruguy commercilizes, for oth orgnic nd conventionl systems, eviscerted crcsses of nimls weighing etween 18 nd 26 g otined from nimls rered during dys. The crcsses of free-rnge or orgniclly produced chickens were generlly lighter thn the conventionl ones [4,31]. In Uruguy, s in other countries, the orgnic chicken met hs een directed towrds consumers who re interested in the respect of niml welfre nd the potentil humn helth qulity ttriute ssocited to the orgnic chicken met. However, the ppernce nd the texture of met remin eqully criticl to the finl selection of the product nd the ultimte cceptnce of the cooked product Colour, ph nd Hem Iron Content In the present investigtion the L* showed higher vlues in orgnic met, compred to conventionl met, t 3 hours nd 24 hours post-mortem. Those vlues could e considered close to the threshold of ple met for the roiler rest met produced in Itly [32]. However, nother investigtion [33] considered L* of 6 limit for ple met in the poultry rest met. Thus, it seems tht there is not vlue of L* which could e estlished s stndrd threshold to discriminte unequivoclly etween ple nd norml poultry met. The ple poultry met with high L* ws often ssocited with low ultimte ph, generlly elow 5.7, in comprison to the norml met. Of course, those results [32,33] were from rest met, ut similr considertion could e ssumed for Srtorius nd Gstrocnemius muscles evluted in the present investigtion. In the report of Swtlnd [34], the sujective selection of ple nd drk rest met of conventionlly produced 6 weeks-old chicken, conducted to the oservtion tht ph of 5.91 ±.12 nd 6.36 ±.25 corresponded to ple nd drk met, respectively. Furthermore, in this sme work, the low ph corresponded to higher light reflectnce, while the higher ph corresponded to lower reflectnce, oth cses ssocited with the microstructure of the muscle fires. In the present investigtion, the recorded ultimte ph showed vlues rnged etween in orgnic met nd in conventionl one. In conclusion, It seems unlikely tht the orgnic muscles evluted in the present investigtion could e considered s ple met in regrd to the reltion etween the L* vlues nd the ultimte ph. Overll in our investigtion, the L* showed higher vlues in orgnic met nd the ultimte ph showed lower vlues in orgnic met, oth compred to the conventionl met. For the redness (*) the comprison etween muscles showed tht the Pectorlis mjor seems to e the muscle with the lower redness in comprison to the other two studied muscles. This result ws in greement to the oservtion reported y others [4,35] nd could proly e ssocited

7 18 Americn Journl of Food nd Nutrition with lower level of hem iron in met detected in the present investigtion, in oth production systems. Hem iron is highly ssocited component of the red colour in poultry met [36]. However, the vritions of * etween the two production systems were not cler. Then, tken together, the comprison etween orgnic nd conventionl met showed, in the present investigtion, n opposite result. Indeed, the * t 3 hours post-mortem were, overll, higher in orgnic met, while the * t 24 hours post-mortem were higher in conventionl met. Moreover in the present investigtion, the conventionl met showed, t 24 hours post-mortem, lower level of hem iron in comprison to the orgnic met. Thus, the impliction of iron pigment in poultry met cnnot e sufficient to explin the difference in redness etween orgnic nd conventionl met. For the yellowness (*), orgnic met showed lower vlues compred to the conventionl met t 3 nd 24 hours post-mortem. Although the vlues of * were close etween the two kinds of met, these differences could e explined y the diet differences etween the orgnic nd the conventionl system. The conventionl system used diet lrgely sed on corn which cts s nturl pigment to ensure the crcss yellowness, while the orgnic system used only reduced mount of Non-geneticlly Modified corn. In Uruguy the no-gmo orgnic corn is rre nd expensive [37], so only limited mount of this corn is used (< 1 %) for the orgnic poultry production system. To compenste this, the orgnic producers included dried lflf to otin n dequte grde of yellowness of the crcsses [38]. In the scientific literture, the vlues of * were highly vrile depending on the level of yellowness required y the mrket. In Uruguy the consumers prefer yellow crcss. The vlues of * oserved in the present investigtion were in the sme order those oserved in nother report [35], ut higher thn those reported y other uthors [4,39], oth working on Ross poultry reed, the sme one used in our investigtion Lipid nd Ftty Acid Composition The totl lipids content of the two muscles showed no difference etween the two production systems. However, the Gstrocnemius muscles showed, s expected [4-42], higher content in lipids thn the Pectorlis mjor for oth orgnic nd conventionl system. The results of the ftty cids composition showed n unexpected difference etween the met from the orgnic system nd the met from the conventionl one. Indeed, when the totl ftty cids were grouped y clss, it ppers tht the polyunsturted ftty cids (PUFA) showed drmtic difference etween the two production systems. The pectorlis mjor nd the Gstrocnemius muscles in orgnic system contin % nd % of PUFA, respectively, while the sme muscles in the conventionl system showed levels of % nd 34, 87 %, respectively. Within the PUFA clss, the n-6 ftty cids showed level of 2.5 to 3 times more in conventionl met thn in orgnic one. These results could proly e explined y the difference of the diet offered to the nimls in the two systems. In the conventionl production system, the diet ws sed minly on corn nd soyen. As linoleic cid is typicl polyunsturted ftty cid present in corn nd soyen, this proly explins why the met of conventionl chickens contined three times more of this ftty cid in comprison to the orgnic chickens. Also, the n-3 ftty cids showed level 2 to 2.6 times more in conventionl thn in orgnic met. In prticulr, the high level of docospenthexenoic cid (DPA) nd the docoshexdecnoic cid (DHA) oserved in the conventionl system cn e explined y the use of fish mel in the diet offered to the nimls. In the orgnic met, the presence of totl n-3 ftty cids (prticulrly DPA nd DHA) could proly e explined y the inclusion of grss nd dry lflf in the diet. This explntion hs een previously suggested for orgnic nd conventionl chicken production system [4,43], nd it hs lso een reported in other non-ruminnt nimls [44,45]. In the sme time, the orgnic met showed higher level of monounsturted ftty cids (MUFA), minly oleic nd plmitoleic ftty cids in the two muscles, in comprison to the conventionl met. Furthermore, Gstrocnemius showed, independently of the production system, higher level of MUFA in comprison to the Pectorlis mjor. Finlly, no differences were oserved for the sturted ftty cids (SFA) in the two muscles for oth production systems. The ftty cids composition of orgnic met should e considered nutritionlly insufficient for humns in regrd to the PUFA content. The min dvntge of chicken met is the interesting level of puf in comprison to others usul mets such s eef, lm nd pig [46]. However, this positive spect of chicken met is sent in the orgnic met evluted in the present investigtion Lipid nd Protein Oxidtion The met from the orgnic system showed level two or three more times lower thn the corresponding muscles of the conventionl system. However, no difference etween muscles ws detected. Although the orgnic met evluted in the present investigtion, could e considered s much more stle thn the conventionl met in regrd to the level of TBARs, the ftty cids composition cn proly explin this result in gret prt. The orgnic met showed in one prt reduced level of PUFA, the min trget of oxidtion process in met, nd in nother prt higher level of MUFA, minly oleic cid, which helps gretly in the lipid stility of ll kinds of met nd other foods. The TBARS oserved in our investigtion, in oth systems, were lower thn those reported in nother investigtion [4] nd higher thn those reported y other uthors [35,42,47]. The protein oxidtion showed no difference etween muscles nd system. The protein oxidtion dmge in met ffects mino cidic residues cusing loss of the protein functionlity ffecting their nutritionl nd orgnoleptic functionlity [48,49]. Reports which studied the protein oxidtion of chicken met re very sprse in the scientific literture to compre with our results [16,5]. However, our results showed tht the orgnic production system did not cuse mjor protein oxidtion of the two studied muscles in comprison to the conventionl one Anti-oxidtive Enzyme Activities The ctivity of SOD showed no difference etween Pectorlis mjor nd Gstrocnemius muscles nor etween

8 Americn Journl of Food nd Nutrition 19 production systems, in the two result expression mode. Unfortuntely, dt on SOD in chicken met, independently of the production system, cnnot e sourced in the scientific literture for comprison. To the contrry, the ctlse ctivity in Pectorlis mjor muscle ws lower thn in Gstrocnemius muscle in the two production systems. Our results gree with those of Jhn et l. [47], who found tht ctlse ctivity ws higher for chicken met from n orgnic production system. Furthermore, other investigtion [13,51], found higher ctlse ctivity in thigh met in comprison to rest met. The reserch done in humn skeletl muscle, efore nd fter exercise, showed significnt increse of ctlse ctivity fter moderte physicl trining. [52]. Thus, chicken rered under the orgnic production system conditions hve ccess to outdoor nd grss pddocks, nd enter the pens only to sleep, so they spend the dy wlking. Even though this exercise of wlking cnnot e considered s physicl trining, it cn e considered s chronic moderte exercise compred to the very low moility of chicken in the conventionl system. So, it could e possile to ttriute the higher ctlse ctivity we found in orgnic chicken muscle met to the exercise they do. Furthermore, the ctlse ctivity ws higher in Gstrocnemius muscles which hs n oxidtive metolism nd lower in the Pectorlis mjor muscle which hs glycolitic metolism. In this sense, our results gree with those of Jenkis & Tengi [53], who found tht oxidtive muscles present higher ctlse ctivity thn glycolytic ones. SOD nd ctlse ct in concert to counterct the oxidtive processes in met, y the trnsformtion of H 2 O 2 into H 2 O nd O 2. The two enzymes re the first line defence ntioxidnts. A third enzyme which lso prticiptes in tht first line of defence is the GPx. In the present investigtion, the GPx showed different results depending how its ctivity ws expressed, i.e. y g of met or y mg of proteins. When the results were expressed y g of met, the orgnic met showed lower ctivity compred to the conventionl one. Also the pectorlis mjor muscle showed lower ctivity thn the Gstrocnemius one. However, no difference ws oserved for the sme muscle in the conventionl system. When the ctivity of GPx ws expressed y mg of protein, no difference etween the two production systems were oserved. However, the Pectorlis mjor muscle showed lower ctivity of GPx in comprison to Gstrocnemius muscle, in oth orgnic nd conventionl systems. This grees with the results of Dun & Åkesson [15], who found tht GPx ctivity ws significntly higher in oxidtive muscles of chicken, duck nd turkey when compred to glycolytic ones. Indeed, it is generlly considered tht oxidtive muscles hve higher GPx ctivities thn glycolytic ones [54]. 5. Conclusion The results of the present investigtion showed tht the orgnic chicken met s produced in Uruguy hs good oxidtive stility. However, this met cnnot e considered dequte for the consumers in regrd to its nutritionl vlue, t lest for PUFA contents. Although the high vlue of the orgnic met resides in its sfety in regrd to chemicl residue nd welfre of the nimls, it s lso indispensle tht the nutritionl vlue of this kind of met must e ensured for the consumers. The notion of nutritionl security hs to e strongly considered in the cse of orgnic chicken met. Most of the regultions which re worldwide pplied, generlly insist much on wht kinds of food hve to e nned nd wht kinds of chemicl tretment hve to e conducted to preserve the met from possile contmintion. However, these sme regultions do not define in nywy, wht kind of dequte nutritionl composition is required in the met for the consumers. There is no dout tht orgnic chicken met hs to e eqully sfe thn nutritive. This prticulr point should e considered in future officil regultions for orgnic chicken met production. A similr viewpoint hs een emitted y Cstellini [55]. In the specific cse of Uruguy, the nned use of GMO food nd the limited vilility of no-gmo corn nd soyen [37] excerted the difficulty of the feed formultion to produce orgnic chicken met, ut this sitution could e done in other prts of the world. It seems importnt in Uruguy to stimulte the emergence of rules which regulte nd monitor the nutritionl composition of the orgnic met or ny other specilly produced chicken met to ensure nutritionl security for the consumers. On the other hnd, the orgnic chicken producers hve to innovte in their feeding strtegy, choosing other PUFA OGM-free source ville in the country or the region, such s the chi, the horse ft or the well known linseed [56,57,58]. Sttement of Competing Interests The uthors hve no competing interests'. References [1] Fntico, A. C., Pilli, P. B., Cvitt, L. C., Emmert, J. L., Meullenet, J. F. nd Owens, C. M., Evlution of slower-growing roiler genotypes grown with nd without outdoor ccess: Sensory ttriutes. Poultry Science 85, [2] ATTRA. Alterntive Poultry Production Systems nd Outdoor Access (ccessed 211/3/3). 21. [3] ATTRA, Lel rouge: Psture-sed poultry production in Frnce. (ccessed 211/3/3). 21. [4] Cstellini, C., Mugni, C. nd Dl Bosco, A., Effect of orgnic production system on roiler crcss nd met qulity. Met Science 6, [5] ITAB, (ccessed 211, mrch 29). 29. [6] Fntico, A. C., Pilli, P. B., J. L. Emmert, J. L. nd Owens, C. M., Met qulity of slow- nd fst-growing chicken genotypes fed low-nutrient or stndrd diets nd rised indoors or with outdoor ccess. Poultry Science 86, [7] Meluzzi, A., Sirri, F., Cstellini, C., Roncrti, A., Melotti, P. nd Frnchini, A., Influence of genotype nd feeding on chemicl composition of orgnic chicken met. Itlin Journl of Animl Science 8, [8] APODU, (Accessed on 211/1/15). 21. [9] Rpl, eto_certificcion.pdf. 28.

9 2 Americn Journl of Food nd Nutrition [1] Tuyttens, F., Heyndrickx, M., De Boeck, M., Moreels, A., Vn Nuffel, A., Vn Poucke, E., Vn Coillie, E., Vn Dongen, S. nd Lens, L., Livestock Science 113, [11] Fntico, A. C., Cvitt, L.C., Pilli, P. B., Emmert, J. L. nd Owens, C. M., Evlution of slower-growing roiler geneotypes grown with nd without outdoor ccess: Met qulity. Poultry Science 84, [12] Gry, J. I.; Gom, E. A. nd Buckley, D. J., Oxidtive qulity nd shelf life of mets. Met Science 43, [13] Rhee, K. S., Anderson, L. M. nd Sms, A. R., Lipid oxidtion potentil of eef, chicken nd pork. Journl of Food Science 61, [14] Morrissey, P. A., Sheehy, P. J. A., Glvin, K., Kerry, J. P. nd Buckley, D.J., Lipid stility in met nd met products. Met Science 49, S73-S [15] Dun, C. nd Åkesson, B., Comprison of glutthione peroxidse ctivity, nd of totl nd solule selenium content in two muscles from chicken, turkey, duck, ostrich nd lm. Food Chemistry 85, [16] Fellenerg, M.A. nd Speisky, H., Antioxidnts: their effects on roiler oxidtive stress nd its met oxidtive stility. World s Poultry Science Journl 62, [17] Ciel Colour System, Commission Interntionl de l Eclirge. Pris: CIE Puliction [18] Hornsey, H. C., The colour of cooked cured pork. 1. Estimtion of the nitric oxide-hem pigments. Journl of the Science of Food nd Agriculture 7, [19] Clrk, E. M., Mhoney, A. W. nd Crpenter, C. E., Heme nd Totl Iron in Redy-to-Et Chicken. Journl of Agriculture nd Food Chemistry 45, [2] Lomrdi-Bocci, G, Mrtinez-Dominguez, B., Aguzzi, Altero nd Rincon-Leon, F., Optimiztion of heme iron nlysis in rw nd cooked red met. Food Chemistry 78, [21] Folch, J., Lees, M. nd Slone-Stnley, G. H., A simple method for the isoltion nd purifiction of totl lipides peptides from niml tissues. Journl of Biologicl Chemistry 226, [22] Ichihr, K, Shihr, A, Ymmoto, K. nd Nkym, T., An improved method for rpid nlysis of the ftty cids of glycerolipids. Lipids 31, [23] Lynch, S. M. nd Frei, B., Mechnisms of copper- nd irondependent oxidtive modifictions of humn low density lipoprotein. Journl of Lipid Reserch 34, [24] Mercier, Y., Gtellier, P. nd Renerre, M., Lipid nd protein oxidtion in vitro, nd Antioxidnt potentil in met from Chrolis cows finished on psture or mixed diet.met Science 66, [25] Mrklund, S. nd Mrklund, G., Involvement of the superoxide nion rdicl in the utooxidtion of pyrogllol nd convenient ssy for superoxide dismutse. Europen Journl of Biochemistry 47, [26] Gtellier, P., Mercier, Y. nd Renerre, M., Effect of diet finishing mode (psture or mixed diet) on ntioxidnt sttus of Chrolis ovine met. Met Science 67, [27] Aei, H., Ctlse in vitro. Methods in Enzymology 15, [28] Günzler, A. nd Flohé, L., Glutthione Peroxidse. In Greenwld, R. A. (ed). CRC Press Inc Boc Rton, Florid, USA, Vol. 1, [29] De Vore, V. R. nd Greene, B. E., Gluthtione peroxidse in postrigor ovine semitendinous muscle. Journl of Food Science 47, [3] Stoscheck, C. M., Quntifiction of protein. Methods in Enzymology 182, [31] Wng, K.H., Shi, S.R., Dou, T.C. nd Sun, H.J., Effect of freernge rising system on growth performnce, crcss yield, nd met qulity of slow-growing chicken. Poultry Science 88, [32] Petrcci, M., Betti, M., Binchi, M. nd Cvni, C., Color vrition nd chrcteriztion of roiler rest met during processing in Itly. Poultry Science 83, [33] Vn Lck, R.L.J.M., Liu, C.H., Smith, M.O. nd Lovedy, H.D., Chrcteristics of ple, soft, exudtive roiler rest met. Poultry Science 79, [34] Swtlnd, H. J., How ph cuses pleness or drkness in chicken rest met. Met Science 8, [35] Husk, R. L., Sernek, J.G. nd Bregendhl, K., A survey of commercilly ville roilers mrketed s orgnic, free-rnge nd conventionl roiler for cooked met yields, met composition, nd reltive vlue. Poultry Science 87, [36] Boulinne, M. nd King, A. J., Biochemicl nd color chrcteristics of skinless oneless ple chicken rest. Poultry Science 74, [37] Gleno, P., Mrtinez Det, C., Ruil, F., Frnco Frgus, L. nd Glvn, G. A., Cross-fertiliztion etween geneticlly modified nd non-geneticlly modified mize crops in Uruguy. Environmentl Biosfety Reserch, DOI:1.151/er/ [38] Cstñed, M. P., Hirschler, E. M. nd Sms, A. R., Skin Pigmenttion Evlution in Broilers Fed Nturl nd Synthetic Pigments. Poultry Science 84, [39] Mouro, J.L., Pinheiro, V.M., Prtes, A.M., Bess, R.J.B., Ferreir, L.M.A., Fontes, C.M.G. nd Ponte, P.I.P., Effect of dietry dehydrted psture nd citrus pulp on the performnce nd met qulity of roiler chickens. Poultry Science 87, [4] O Keefe, S. F., Proudfoot, F. G. nd Ackmn, R. G., Lipid oxidtion in mets of omeg-3 ftty cid-enriched roiler chickens. Food Reserch Interntion 28, [41] Mourot, J. nd Hermier, D., Lipids in monogstric nimls met. Reproduction Nutrition development 41, [42] Binchi, M., Ferioli, F., Petrcci, M., Coni, M. F., nd Cvni, C., The influence of dietry lipid source on qulity chrcteristics of rw nd processed chicken met. Europen Food Reserch Technology 229, [43] Ponte, P. I. P., Prtes, J. A. M., Crespo, J. P., Crespo, D. G., Mouro, J. L., Alves, S. P., Bess, R. J. B., Chveiro-Surez, M. A., Ferreir, L. M. A. nd Fontes, C. M. G. A., Improving the lipid nutritive vlue of poultry met through the incorportion of dehydrted leguminous-sed forge in the diet for roiler chicks. Poultry Science 87, [44] Muriel, E., Ruiz, J., Ventns, J. nd Antequer, T., Free-rnge rering increses (n-3) polyunsturted ftty cids of neutrl nd polr lipids in swine muscles. Food Chemistry 78, [45] Forrester-Anderson, I.T., McNitt, J., Wy, R. nd Wy, M., Ftty cid content of psture-rered fryer rit met. Journl of Composition nd Anlysis 19, [46] Sdoun, A. nd Crer, M. C., A review of the nutritionl content nd technologicl prmeters of indigenous sources of met in South Americ. Met Science 8, [47] Jhn, K., Pterson, A. nd Spickett, C. M., Ftty cid composition, ntioxidnts nd lipid oxidtion in chicken rests from different production regimes. Interntionl Journl of Food Science nd Technology 39, [48] Mercier, Y., Gtellier, P., Viu, M., Remington, H. nd Renerre, M., Effect of dietry ft nd vitmin E on colour stility nd on lipid nd protein oxidtion in turkey met during storge. Met Science 48, [49] Gtellier, P., Mercier, Y., Rock, E. nd Renerre, M., Influence of dietry ft nd vitmin E supplementtion on free rdicl production nd on lipid nd protein oxidtion in turkey muscle extrcts. Journl of Agriculturl nd Food Chemistry, 48, [5] Liu, G. nd Xiong, Y.L., Contriution of lipid nd protein oxidtion to rheologicl differences etween chicken white nd red muscle myofirillr proteins. Journl of Agriculturl nd Food Chemistry 44, [51] Prdhn, A.A., Rhee, K.S. nd Hernndez P., Stility of ctlse nd its potentil role in lipid oxidtion in met. Met Science 54, [52] Prise, G., Phillips, S.M., Kczor, J.J. nd Trnopolsky, M.A., Antioxidnt enzyme ctivity is up-regulted fter unilterl resistnce exercise trining in older dults. Free Rdicl Biology nd Medicine 39, [53] Jenkins, R.R. nd Tengi, J., Ctlse ctivity in skeletl muscle of vrying fire types. Experienti 37, [54] De Vore, V.R. Colngo, G.L., Jensen, L.S. nd Greene, B.E., Thiorituric cid vlues nd glutthione peroxidse ctivity in met from chickens fed selenium-supplemented diet. Journl of Food Science 48, [55] Cstellini, C., Orgnic poultry production system nd met chrcteristics, in XVIIth Europen Symposium on the Qulity of Poultry Met. Doorwerth, The Netherlnds My 25. [56] Lopez-Ferrer, S., Bucells, M. D., Brroet, A. C., Glort, J. nd Grshorn, M. A., n-3 enrichment of chicken met. 2. Use of

10 Americn Journl of Food nd Nutrition 21 precursors of long-chin polyunsturted ftty cids:linseed oil. Poultry Science 8, [57] Crer, M. C., Sdoun, A., Grompone, A., Pgno, T, Slhi, M., Olivero, R. nd del Puerto, M., Enriching the egg yolk in n-3 ftty cids y feeding hens with diets contining horse ft produced in Uruguy. Food Chemistry 98, [58] Cotes, W. nd Ayerz, R., Chi (Slvi hispnic L.) seed s n n-3 ftty cid source for finishing pigs: Effects on ftty cids composition nd ft stility of the met nd internl ft, growth performnce, nd met sensory chrcteristics. Journl of Animl Science 87,