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Methods and Their Applications for Measuring                   225
  VetBooks.ir  Two methods are used for analyzing 2-TBARSs in meat products that


            are widely used in the meat industry (Fig. 6.16). The distillation method
            involves partitioning secondary oxidation products in the meat sample into
            the appropriate  solvent then separating  these compounds by distillation.
            The direct  method  determines  the concentration  of secondary oxidation
            products directly without partitioning the secondary oxidation products or


                         Methods for QuantifYing 2- Thiobarbituric Acid Reactive Substances in  Meats
                                       Generalize Flow Diagram
                                                     TBARS
                               I               I   Distillation Methods   I

                             with
                                      TBARS for Beef          TBARS for Poultry
                                  I                I       I
               Transfer an aliquot  of lh e test   I   TBARS for Pork   I
               so ln.  into test tube conta ining
               the recommended  quant ity of
               TBA reagent.                                I Weigh sample add  I :3  w/v in
                                                           trichloroacetic acid and
                                                           homogenize.
                            ,.                                     +
                                                           I Vacuum  filter homogenate
                                                           through Watman #42 ash less
                                                           filter paper.
                                                                   t
               Cool,  pipette sample into
               cuvette, read absorbance  at                I Add TBA reagent incubate in
               530nm from calibrated                       boiling for 40 min ..
               spectrophotometer with b  and    t
               width < 5nm.  Determine cone,
               using Beer Lambert Law      Conduct "spike and      !
                                           recovery" with  a
                                           small  aliquot of
                               Pipette an aliquot or   standardized soln. of   Cool, then pipette into cuvette,
                               distillate from meat   MDA-bis acetaL   read absorbance at 530 nm  in
                               homogenate into test        calibrated spectrophotomer,
                               tube with TBA               band width < 5nm.  Calculate
                               rea ~ent.                   cone.  Using Beer Lambert Law

                                          ~
                              I Pipette an aliquot of distillate from meat
                              homogenate into test tube with TBA reagent.   I
                                          ~            ~

                             Incubate in boiling water for 35 min., cool then pipette
                             sample into cuvette.  Read absorbance at 530nm from
                             calibrated spectrophotometer with spectral band width
                             < Snm.  Determine cone,  use  Beer Lambert Law.


            FIGURE 6.16  Methods and techniques  for the  analysis of  TBARS (thiobarbituric  acid
            reactive substances).
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