Some aspects of nutritive and sensory quality of meat of restrictively fattened chickens

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1 Chiken met qulity: T. Komprd nd J. Zelenk Some spets of nutritive nd sensory qulity of met of restritively fttened hikens T. KOMPRDA 1 * nd J. ZELENKA 2 1 Deprtment of Food Tehnology 2 Deprtment of Animl Nutrition, Mendel University Brno, Zemědělská 1, Brno, Czeh Repuli *komprd@mendelu.z Keywords: holesterol; rhidoni id; very-long-hin polyunsturted ftty ids; flvour; tenderness Summry Femle hikens (Ross 208), divided in four groups of 18 irds eh, were fed one of the following respetive diets: whole-whet type fed restritively (WR), mize-mel type fed restritively (MR), mize-mel type fed semi-d liitum (MS) nd ontrol ommeril feed mixture (C). Birds of the three experimentl groups were slughtered when they rehed live weight 2200 g (87, 90 nd 74 dys of ge for WR, MR nd MS group, respetively), C-hikens were slughtered t the ge of 46 dys. Sensory trits of hiken met (olour, firousness, odour, tenderness, juiiness nd flvour) were evluted y pnel of eight ssessors within three onseutive sessions. Met tenderness deresed in the following sequene of the diets: C > MS > oth restritively fed diets. Both rest met nd thigh met of MS-hikens ws etter sored (P<0.01) from the sensoril viewpoint in omprison with the C-irds. It ws onluded, tht on the one hnd, it is possile to produe met with higher orgnolepti qulity using hikens of ommon met hyrid omintion on the ssumption tht the rehing of the desirle slughter weight is delyed to the higher ge (12 weeks) due to the quntittive nd qulittive (lower protein ontent) feed restrition. However, on the other hnd, slowly growing hikens of ll experimentl groups deposited in met more (P<0.01) holesterol (in verge y 20 %) nd in verge seven times more (P<0.01) rhidoni id in omprison with the ontrol group. Met of hikens fttened deliertely slow y the erel diets nd slughtered t twelve weeks of ge ws therefore less fvourle from the viewpoint of helthy humn nutrition thn met of onventionlly fed roilers slughtered t six weeks of ge. Introdution Most produers im to ftten hikens to desirle slughter weight s quikly s possile. However, the met of rpidly fttened hikens is onsidered tsteless nd not firm enough. Therefore some produers ftten hikens deliertely slow to higher ge to hieve higher sensory qulity of the produt (Culioli et l., 1990). On the other hnd, ppers onerning the nutritive vlue, espeilly the omposition of the lipid frtion of suh produt, re sre (Komprd et l., 2000). Both dietry holesterol nd ftty id pttern in the dietry lipid frtion re in lose reltionship to serious hroni diseses in humns. As fr s ftty ids re onerned, the derese of polyunsturted ftty ids (PUFA) n-6/n-3 rtio in the diet, nd espeilly the derese of rhidoni id (AA) intke re reommended (Ter et l., 1998). The ojetive of the present study ws to ompre met of hikens fttened deliertely slow to higher ge y the diets sed nerly exlusively on erels, with typilly intensively fed hikens, slughtered upon rehing omprle live weight, regrding holesterol ontent nd ontent of physiologilly most importnt ftty ids on the one hnd, nd sensoril qulity on the other hnd. Mteril nd methods Femle hikens (Ross 208), divided in four groups of 18 irds eh, were fed one of the following respetive diets: whole-whet type fed restritively (WR), mize-mel type fed restritively (MR), mize-mel type fed semi-d liitum (MS) nd ontrol ommeril feed mixture (C). Birds were slughtered when they rehed live weight 2200 g, tht is 87, 90 nd 74 dys of ge for WR, MR nd MS group, respetively; C-hikens were slughtered t the ge of 46 dys. After slughter nd XVII th Europen Symposium on the Qulity of Poultry Met Doorwerth, The Netherlnds, My

2 Chiken met qulity: T. Komprd nd J. Zelenk ooling, rest musles () nd thigh musles () were seprted from twelve rsses within eh group of hikens, frozen nd stored t 20 C until nlyses. Consequently, totl lipids in the tissues were extrted y hexne/2-propnol mixture, nd holesterol nd ftty ids were determined y liquid hromtogrphy nd gs hromtogrphy, respetively (ording to Komprd et l., 2000). Six rsses from eh group of hikens were frozen, stored t 20 C nd onsequently used in sensory nlysis. Sensory trits of hiken nd (olour, firousness, odour, tenderness, juiiness nd flvour) were evluted y pnel of eight ssessors within three onseutive sessions. A 100 mm unstrutured line sle ws used for ll desriptors with the nhor points loted 20 mm from oth ends of given line sle. Before session, rsses were defrosted overnight, divided into the portions (, ) nd ooked one hour t 200 C. One-wy lssifition nd four-wy lssifition with intertion, inluding Dunn multiple-rnge test, ws used within the nlysis of vrine regrding nutritive nd sensory trits, respetively. Results nd disussion The tretment (diet omposition, inluding the method of fttening) influened (P<0.01) olour, firousness nd tenderness of nd ll sensoril trits of, exept odour. A signifint (P<0.01) effet of the ssessor on quntifition of most trits of sensory qulity ws found. The ssessors oinided only in the trit of tenderness in (P>0.05). No intertion diet-ssessor ws found in ny sensoril trit either in or in. However, signifint intertions (P<0.01) diet-session were found in olour nd tenderness in, nd odour, tenderness nd flvour in thigh met. Chikens of ll three experimentl groups hd drker (P<0.01) nd in omprison with the C-group. Tenderness of tended to derese in the sequene ontrol hikens > hikens fed semi-d liitum > restritively fed hikens. Only of hikens fed the whet-type diet nd slughtered t the ge of 14 weeks ws signifintly tougher (P<0.01) in omprison with of hikens of ll other groups. However, s fr s is onerned, n unmiguous nd signifint (P<0.01) derese of tenderness with inresing slughter ge of hikens ws oserved. We found differenes (P<0.01) etween the diets regrding juiiness of ut not of. This ft n e explined y sustntilly higher ft ontent of (21.5, 38.3, 44.8 nd 55.4 % in C, WR, MR nd MS group) in omprison with (7.7, 12.7, 16.0 nd 14.7 % in C, WR, MR nd MS group, respetively), nd y signifint differenes (P<0.01) etween totl lipid ontent in of hikens fed the different diets. Regrding flvour, only nd of MS hikens (ut not of other experimentl groups) ws etter sored in omprison with C-roilers (Figure 1). Chikens fed the mize-type diet semi d-liitum hd higher (P<0.01) holesterol ontent oth in nd in thn whet-type diet fed hikens (Figure 2). Moreover, hikens of ll experimentl groups deposited more (P<0.01) holesterol in oth tissues in omprison with trditionlly fed ontrol irds. The reson ws proly not higher totl lipid ontent in met of experimentl hikens (ording to Hoelsher et l., 1988, holesterol ontent in the musle tissue did not hnge with n inrese of intrmusulr ft ontent), ut rther muh higher growth intensity of C-hikens (Komprd et l., 1999, found signifint derese of holesterol ontent in the lipid frtion of nd with inresing growth intensity of hikens), nd/or ftty id omposition of the diets. It is generlly epted (Jones et l., 1990), tht higher sturted ftty id (SFA) ontent inreses, nd higher monounsturted ftty id (MUFA) nd PUFA ontent dereses totl plsmti holesterol. Experimentl diets hd on verge 65 % higher SFA ontent nd nerly 60 % lower MUFA ontent in omprison with the ontrol diet in the present experiment. As fr s PUFA n-6 re onerned, physiologilly most importnt metolite of the prent sustne, linolei id (LA), is rhidoni id (AA). AA-derived eiosnoids re proinflmmtory nd proggregtory; higher AA intke is therefore unfvourle (Ter et l., 1998). Ft from poultry met ould e signifint ontriution to the dietry intke of AA (Li et l., 1998), whih ws onfirmed in the present experiment (Figure 3). Sustntilly higher (P<0.01) AA ontent in the tissues of ll groups of experimentl hikens s ompred to the ontrol group ws proly onsequene of unfvourle linolei id/α-linoleni id rtio in the prtiulr diets (9.2, 17.5, 25.9 nd 25,9 in the C, WR, MR nd MS diet, respetively). Contrry to AA-derived eiosnoids, eiosnoids derived from n-3 PUFA, eiospentenoi id (EPA) nd dooshexenoi id (DHA; metolites of α-linoleni id, LNA), use vsodiltion nd re ntiggregtive. Inresing the intke of n-3 PUFA is sfe nd effetive mens in reduing moridity nd mortlity fter myordil infrtion (vonshky, 2001). Antiinflmmtory properties of n-3 PUFA in the rteril wll my ontriute to their protetive effets on rdiovsulr diseses (Yqoo, 2004). Beuse LNA nd its very-long-hin (VLC) metolites (EPA + DHA) re not XVII th Europen Symposium on the Qulity of Poultry Met Doorwerth, The Netherlnds, My

3 Chiken met qulity: T. Komprd nd J. Zelenk iologilly equivlent, suggested Ollis et l. (1999) the use of the so-lled VLC n-3 PUFA equivlents (VLCE): VLCE = 0.15LNA + EPA + DHA (in mg/100 g of the tissue). VLCE vlues found in the present experiment re shown in Figure 4. VLCE ontent in oth nd of hikens of ll three experimentl groups were higher in omprison with the ontrol group, due to the higher ft ontent in the prtiulr tissues of WR, MR nd MS hikens. From the viewpoint of helthy humn nutrition, to keep the proper lne etween intke of n-6 nd n-3 PUFA is mtter of the utmost importne. Okuym et l. (1997) reommended the PUFA n-6/pufan-3 rtio to e 2 or elow. As it is pprent from the Figure 5, neither met of experimentl hikens, nor met of the ontrol ones ws n idel food from this viewpoint in the present experiment. However, of MS hikens, nd of oth MR nd MS hikens ws still worse in this trit (P<0.01) in omprison with the ontrol group. Conlusions The present study proved tht hikens fttened y mize-sed erel mixture nd slughtered t the ge of ten weeks were more flvourle in omprison with roilers fed ommeril finisher nd slughtered t the ge of six weeks. However, within the time intervl followed in this experiment, we were not le to onfirm the hypothesis tht the higher slughter ge of hikens yields more flvourful produt. This ws in prt used y the ft, tht the primry effet on sensory qulity ws tht of the diet (inluding the method of fttening) nd not tht of the slughter ge. On the other hnd, sed on the nutritive trits importnt from the viewpoint of the urrent trends in the evlution of the reltionship etween omposition of niml produts nd serious hroni diseses in humns (totl lipid, holesterol, rhidoni id, very-long-hin PUFA), met of intentionlly slow fttened hikens were onsidered less fvourle produt (with the exeption of VLC PUFA) thn met of ommerilly fed roilers. We estimted n verge intke of the ove onstituents in 200 g of hiken met (100 g of g of ). The intke in met of slow growing hikens fed the erel diets (men of ll three experimentl groups, WR, MR, MS), expressed in the solute vlues nd s per ent of the intke vi 200 g of met of onventionlly, intensively fttened hikens (in prentheses) ws s follows: totl lipid 29.2 g (170 %), holesterol 127 mg (120 %), rhidoni id 2105 mg (700 %), VLC PUFA equivlent 429 mg (255 %). Referenes Culioli, J., Tourille, C., Bordes, P. nd Girud, J.P. (1990) Crteristiques des rsses et de l vinde du poulet lel fermier. Arhiv für Geflügelkunde 53: Hoelsher, L.M., Svell, J.W., Smith, S.B. nd Cross, H.R. (1988) Suellulr distriution of holesterol within musle nd dipose tissue of eef loin steks. Journl of Food Siene 53: Komprd, T., Zelenk, J., Tieffová, P., Štohndlová, M. nd Foltýn, J. (1999) Effet of the growth intensity on holesterol nd ftty ids ontent in roiler hiken tissues. Arhiv für Geflügelkunde 63: Komprd, T., Zelenk, J., Tieffová, P., Štohndlová, M., Foltýn, J. nd Fjmonová, E. (2000) Effet of ge on totl lipid, holesterol nd ftty ids ontent in tissues of fst nd slow growing hikens. Arhiv für Geflügelkunde 64: Li, D., Ng, A. nd Sinlir, A.J. (1998) Contriution of met ft to dietry rhidoni id. Lipids 33: Okuym, H., Koyshi, T. nd Wtne, S. (1997) Dietry ftty ids the n-6/n-3 lne nd hroni elderly diseses. Exess linolei id nd reltive n-3 defiieny syndrome seen in Jpn. Progress in Lipid Reserh 35: Ollis, T.E, Meyer, B.J. nd Howe, P.R.C. (1999) Austrlin food soures nd intkes of omeg-6 nd omeg-3 polyunsturted ftty ids. Annls of Nutrition nd Metolism 43: Ter, L., Chiu, C.-H. nd Wheln, J. (1998) Assessment of the rhidoni id ontent in foods ommonly onsumed in the Amerin diet. Lipids 33, von Shky, C. (2001) Clinil trils, not n-6 to n-3 rtios, will resolve whether ftty ids prevent oronry hert disese. Europen Journl of Lipid Siene nd Tehnology 103: Yqoo, P. (2004) Ftty ids nd the immune system: from si siene to linil pplitions. Proeedings of the Nutritionl Soiety 63: XVII th Europen Symposium on the Qulity of Poultry Met Doorwerth, The Netherlnds, My

4 Chiken met qulity: T. Komprd nd J. Zelenk Figure 1 Met flvour mm of the unstrutured line sle ,, C - ontrol ommeril feed mixture; WR - whole-whet type diet fed restritively; MR - mize-mel type diet fed restritively, MS - mize-mel type diet fed semi-d liitum rest met; thigh met, mens with different supersripts within given tissue differ signifintly (P<0.01) Figure 2 Cholesterol ontent mg/100 g , C, WR, MR, MS;, see Figure 1,, mens with different supersripts within given tissue differ signifintly (P<0.01) XVII th Europen Symposium on the Qulity of Poultry Met Doorwerth, The Netherlnds, My

5 Chiken met qulity: T. Komprd nd J. Zelenk mg/100 g Figure 3 Arhidoni id C, WR, MR, MS;, see Figure 1,, mens with different supersripts within given tissue differ signifintly (P<0.01) Figure 4 Very-long-hin polyunsturted ftty id equivlent* mg/100 g , 50 * VLCE = 0.15 α-linoleni id + eiospentenoi id + dooshexenoi id ontent (ll vlues in mg/100 g of tissue) C, WR, MR, MS;, see Figure 1,, mens with different supersripts within given tissue differ signifintly (P<0.01) XVII th Europen Symposium on the Qulity of Poultry Met Doorwerth, The Netherlnds, My

6 Chiken met qulity: T. Komprd nd J. Zelenk Figure 5 Polyunsturted ftty id n-6/n-3 rtio C, WR, MR, MS;, see Figure 1, mens with different supersripts within given tissue differ signifintly (P<0.01) XVII th Europen Symposium on the Qulity of Poultry Met Doorwerth, The Netherlnds, My