Beef Muscle Characteristics as Related to Carcass Grade, Carcass Weight, and Degree of Aging

Abstract

I 050 ,JulllluryA\lglIst.October, lle(!f gmdcs were revil;cil ill ])eecmher lImO, hut: all rcslilts l:l!)lOl'ted jlJ this bulletin nrc 011 the husis of the gru(]es cllI:l'clltly 111 \Hit!, .2cnssc1nssification, and stl.mples were cut from cnrcns.c;es of the appropri ate .trades:from the cooler stocks of.the e packing compmty.l)etl\,ile<l descl'iptions of the Cltrcnsses seleded itll(l the feeding h.istory of.th(', Itni J)lals (when known) were oubtined for :future reference in intel'pl'eLing resnUs.Generlllly, (;lIe cuts for st.udy were oubtined Itpproximlltely 48 hOlll's Idtel' the ttni.mnJswere, shLught.ered.The LO'llgi,w~imJll8 <101'8i of the rib Ilud th(', ~"{e:III,iten<li:It(},'m,~ muscl(' of the rOllnd were sampled immedi Iltely, Ilnd niter 2 IlUd.4 weeks' aging of tht' cuts Itt a3-ailO F. (During the.thit'(l )'etll' of the st.udy, en!:s from the lightweight CII,rcnsses ill ellC'h of the ~l'IIdes wen' nged i'ol' only;2 weeks.)Sampling Pro.cedure.ItnIlH. .ldi Iltely upon nl'ri \'ILI of the whole slLle euts Itt the lauontlol',Y they wel.'ephotQgl'a,phed ILnd sampling per formed in It eooler: at, 45 :IT.as fol lows: From the. left rib cut of each CILl'CiISS, two rib steaks, 1% inehes thick, '\"el'e cnt for cooking, The 12th-riu stellk was llood far ehemiea,1 and hist.ologiealstudies on fhe (:ooked melli' whUe thn 11th-I'il> stell,k was used for pltnel scoring of pldn.f'nuil ity of Uw cooked lIIellt.The 11-1~ rib seetion WIIS l'eHlm'ed fl'OIll t he right I'ib ~~u~ ILlld the.l'ibeYl' musdl'. (L(YIlg188UJI'II8 (/01'8/) WIIS ctLl'efully l'emo\'ed ILIld freed fl'OIIl nIl adhering fat Itnd conneeti ve tis Sill.'.The niusele WIlS then cut" info two appl'oximILte.l.r e9"aJ pieees plu:aUel to Ole gt'alll of the meat.Conductance ll1ellSlu'emenls and pcnetl'Omet:er.'readings were made immediately 011 the "ft'efihly Cllt pie<;es.Thill sliees were re moved fl'om the ceniet' of the muscle it) I.' histolQgicltl eXILlninntion ILIld uioehem.icalstudies.TllI'ee 01' fOUL' cylinders, one-lULlf iudt ill diameter ILnd apploxilllat:ely2% inches long, were <!lu'cfu1\y cut out pl~mUel to tihe l1lusde fihers IIntIused for sheiLI' tests.The nm.millder 01' the muscle