Predicting Ribeye Palatability at 36 hr

1
Predicting Ribeye Palatability at 36 hr
R.M. Johnson, M.S. Updike, H. Zerby, J.C. Sawdy,
M. Wick Department of Animal Sciences, The Ohio
State University, Columbus, OH
METHODS Cont
RESULTS AND DISSCUSSION Cont
INTRODUCTION

• Inconsistency in beef palatability is a
  characteristic that is steadily rising in
  importance to producers, processors, and
  consumers. Research shows that consumers are
  prepared to pay a higher price for meat
  guaranteed to be flavorful (1) .
• The inability of the beef industry to predict
  palatability inhibits the selective pricing of
  meat into economically important categories based
  on quality.
• The cellular and molecular mechanisms controlling
  meat palatability are not well understood.
• The central hypothesis for this project was that
  postmortem changes in muscle proteins associated
  with overall palatability of the l. dorsi are
  quantifiable by 36 hours postmortem by
  differential electrophoretic analysis, prior to
  carcass fabrication, and that the proteins and
  peptides associated with overall palatability
  will serve as accurate predictors of overall
  palatability of the l. dorsi after 7 days of
  aging. We have formulated this hypothesis based
  on our published and preliminary data in which we
  show multiple readily detectable changes in
  one-dimensional electrophoretic protein profiles
  in beef muscle tissue within 36 hours postmortem.
  

• The intensity 5 bands were found to be either
  positively or negatively associated with overall
  acceptability of ribeye steaks derived from beef
  carcasses aged 7 days (Table 1).
• The results of this research can have many
  benefits for the beef industry
• Because the identity of the proteins correlating
  with taste will be known, producers could select
  for these proteins in future generations,
  eventually leading to a cattle population that
  has greater and more consistent palatability.
• Producers employ selective breeding stratagies
  based on palatability, since they would know
  which animals would be most palatable, and hence
  more valuable.
• Consumers would benefit by receiving a more
  superior end-product and would be confident that
  they were getting the quality they pay for.
• For muscle biology research, the identified
  peptides will increase our knowledge of the
  mechanisms underlying postmortem aging in
  skeletal muscle.
• The long term goal of this laboratory is to apply
  the method developed by Sawdy et al., 2004, for
  myofibrils to identify peptides associated with
  taste and eventually use the findings to develop
  antigens for the production of polyclonal or
  monoclonal antibodies to identify and separate
  carcasses into classes of economic importance.

• Statistical Analysis (cont). Terms in the model
  (Xij) were added sequentially using the STEPWISE
  option of the REG procedure of SAS v.8.1, with a
  threshold probability of 0.25. The procedure
  used seven iterations to identify the terms (i)
  in the final model. The root mean square error
  (RMSE) was partitioned into lack-of-fit and pure
  error components (Draper and Smith, 1988). The
  total error variance was not significantly larger
  than the pure error variance (P gt 0.10),
  indicating that the model has prediction errors
  that are of the same magnitude as those of the
  WBS measurements themselves.
• Proteomic analyses. Protein concentrat-ions were
  determined by a bicinchoninic acid (BCA) assay
  according to manufacturers protocol (Pierce
  Endogen, Rockford, IL). 1-D SDS-PAGE, a powerful
  biochemical tool, was used to separate the
  proteins into bands based on size in response to
  an electric current. A discontinuous gel was
  used, with a 3 acrylamide stacking gel and 10
  acrylamide resolving gel. After electrophoresis,
  the gels were stained using Colloidal-Coomassie
  Blue and then subsequently destained using double
  distilled water. Gels were then scanned into a
  computer.

RESULTS AND DISSCUSSION
METHODS

• Tissue preparation. Samples were removed from the
  l. dorsi from animals harvested according to USDA
  inspection standards in a commercial meat
  processing plant in Orrville, OH, and placed in
  reducing buffer. Steaks were removed from the
  same animals and frozen prior to tenderness
  analyses. A combination of techniques, including
  SDS-PAGE and Mass Spectrometry, were used to
  identify and characterize the peptides.
• Sensory analysis. Steaks were thawed and allowed
  to equilibrate to an internal temperature of 4
  C. The steaks were cooked using a Lincoln
  Inpinger conveyor oven (model 1132-000-A), set
  to 190.5 C, with a cooking time of 14 minutes.
  Internal temperature of the cooked steaks was
  measured using an Ashcroft thermometer (model
  ATFX 392 SKW). The cooked steaks were then
  cooled to room temperature and evaluated for
  overall acceptability by an 11 member trained
  taste panel conducted in the Meat Science
  Laboratory at The Ohio State University.
• Statistical analysis. A prediction model of WBS
  was developed by regressing the WBS values on the
  pixel values from each of the identified bands
  according to the following linear model
• WBSi b0 bjXij ei
• Where
• WBSi is the Warner-Bratzler Shear force
  measurement of the ith sample, i
  1,, 20
• b0 is the intercept
• bj is the regression parameter associated
  with the jth Band
• Xij is the pixel density for the jth Band of
  the ith sample
• ei is the residual error term, iid N(0,s2)

Table 1. Proteins identified as contributing to
Palatability
LITERATURE CITED

• Boleman, S.J., S.L. Boleman, R.K. Miller, J.F.
  Taylor, H.R. Cross, T.L. Wheeler, M. Koohmaraie,
  S.D. Shackelford, M.F. Miller, R.L. West, D.D.
  Johnson, J.W. Savell. 1997. Consumer evaluation
  of beef of known categories of tenderness. J.
  Anim Sci. 75(6)1521-4.
• Sawdy, J.C., N.R. St-Pierre, M.P. Wick. 2004.
  Myofibrillar 1-D fingerprints and myosin heavy
  chain MS analyses of beef loin at 36 hours
  postmortem correlate with tenderness at 7 days.
  Meat Sci. 67421426.

Figure 1. Representative lanes from a 10
SDS-PAGE of myofibrillar proteins isolated from
beef at 36 h postmortem exhibiting bands
associated with acceptability.