2009_Book_FoodChemistry

12.10 Meat Analysis 609
proved to be valuable when the electropherograms
of the protein extracts reveal protein zones
or bands specific for the protein source. Thus,
in meat analysis, such a method allows for the
differentiation between more than 40 animal
species, e. g., beef, pork, horse, buffalo, sheep,
game, and poultry (cf. Fig. 12.38).
To carry out an analyis, the sarcoplasm proteins
are extracted with water. The electrophoretic
separation is predominantly conducted on polyacrylamide
gels, previously also on starch and
agarose gels. The application of a pH gradient
(isoelectric focusing) provides excellent protein
patterns. The first assignment is achieved directly
after the electrophoretic separation on the basis
of two red myoglobin zones (Fig. 12.38a). The
ratio of the intensities of these zones, which
represent met- and oxymyoglobin, changes with
the storage time of the meat or extract and is
not important for evaluation. The myoglobin
and hemoglobin zones can be intensified by
treatment with o-dianisidine/H 2 O 2 (Fig. 12.38b)
and subsequent staining with coomassie brilliant
blue makes all the proteins visible (12.38 c).
Some animal species can be recognized via
the myoglobin bands (e. g., beef, buffalo, pork,
horse, red and grey kangaroo) and others are
assigned to groups. The identification is achieved
with electropherograms stained with coomassie
blue (Fig. 12.39). A differentiation within the
families Cervidae (deer) and Bovidae (horned
animals) is difficult, with the exception of the
subfamily Bovinae (cattle), e. g., between roe
deer, fallow buck, elk, reindeer, kudu, springbok,
Fig. 12.38. Separation of sarcoplasm proteins of various warm blooded animals (mammals and fowl) by isoelectric
focusing on polyacrylamide gels (PAGIF, PAGplate, pH range 3.5–9.5). (according to Kaiser, 1988).
a Myoglobin (and hemoglobin) zones without staining; b Myoglobin and hemoglobin zones after treatment with
o-dianisidine/H 2 O 2 ; c Protein zones after staining with coomassie brilliant blue