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12.10 Meat Analysis 611

Fig. 12.41. Differentiation of fresh liver (1) from frozen

and thawed liver (2) by electrophoretic separation

of glutamate-oxalacetate transaminases (a) GOT sarcoplasm,

(b) GOT mitochondria (according to Hamm

and Mašić, 1975)

The enzyme β-hydroxyacyl-CoA-dehydrogenase

(HADH, EC 1.1.1.35) is also suitable for the

detection of frozen meat or fish. In the oxidation

of fatty acids, HADH catalyzes the reaction

shown in Formula 12.29. This enzyme is bound

to the inner membrane of mitochondria and is

liberated in the freeze/thaw process. Its activity

can then be measured in the issuing sap with

acetoacetyl CoA or with the artificial substrate

N-acetylacetoacetylcysteamine.

3-Oxoacyl-CoA + NADH + H ⊕ →

(S)-3-Hydroxyacyl-CoA + NAD ⊕ (12.29)

Fig. 12.40. Blended beef and pork meat: Densitograms

of sarcoplasm proteins separated by PAGIF and PAGplate;

pH range 3.5–9.5. B/P (beef/pork) blend ratios in

weight %. (according to Kaiser, 1980b)

ical process, isoenzyme blending will occur in the

cytoplasm.

Such membrane damage has been observed by

freezing and thawing of tissue, for example, of

muscle tissue, in which the isoenzymes of glutamate

oxalacetate transaminase (GOT) bound to

mitochondrial membranes are partially released

and found in the sarcoplasm. The pressed sap

collected from fresh unfroze meat has only sarcoplasm

enzymes, while the frozen and thawed

meat has, in addition, the isoenzymes derived

from mitochondria. The GOT isoenzymes can be

separated by electrophoresis (Fig. 12.41). This

procedure is also applicable to fish.

12.10.1.3 Pigments

Pigment analysis is carried out for the evaluation

of meat freshness. The individual pigments, such

as myoglobin (purple-red), oxymyoglobin (red)

and metmyoglobin (brown), are determined.

12.10.1.4 Treatment with Proteinase

Preparations

Proteinases injected intramuscularly or through

blood vessels degrade the structural proteins and,

hence, proteolytic enzymes can be used to soften

or tenderize meat. The enzymes are of plant or

microbial origin and are used in the meat and

poultry industries, while some are also used in the

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