Chemistry Reference
In-Depth Information
Table 12.7
TGase applications in processed meat systems.
Application
References
Gelation of meat proteins
Beef
141, 142
Pork
143
Poultry
59, 88, 134, 144-147
Texture of meat model systems
Beef
129, 148, 149
Pork
150-153
Poultry
135, 154, 155
Texture of sausages and hams
128, 130, 156
salts using TGase. Binding strength can be boosted at low temperatures with caseinate
added to the system as an extender. Caseinate is an excellent substrate for TGase. No data,
however, have been reported on how the treatment affected the product characteristics in
a heated state. Lee and Park
138
showed that hardness, chewiness and springiness increased
significantly by adding TGase to the restructured ground lean pork. Water-holding capacity
(WHC) of unheated samples decreased due to TGase, but the enzyme had no effect on
the cooking loss. Kolle and Savell
140
reported a study on consumers' attitudes towards
restructured beef muscles. The beef muscles studied were free of 'kernel' fat and heavy
connective tissue. TGase and caseinate were used as binding agents to restructure the meat.
In the study, consumers rated cooked restructured products higher than non-restructured
controls in several palatability traits, for example juiciness, flavour and overall like.
12.6.2 Processed meat systems
In addition to binding fresh meat pieces together, the effects of TGase have been studied
in isolated meat protein systems and model meat products aiming at improved textural
properties (Table 12.7).
Although meat protein cross-linking has hitherto been carried out almost solely by TGase,
tyrosinases and laccases are also known to be capable of cross-linking meat proteins and
increasing the firmness of meat systems.
6, 67, 135, 157, 158
TGase-catalyzed formation of additional covalent bonds in structural meat proteins leads,
by definition, to firmer gel structures as has been clearly shown in many studies (Table 12.7).
However, excessive increase in gel firmness due to additional formation of transverse bonds
in the myofibrillar protein network may cause constraint in protein mobility and flexibility
of myofibrils, leading to an undesired decrease in water holding.
106
Decreased WHC is
mostly an unwanted phenomenon and has been observed to take place particularly in heated
comminuted meat systems particularly when salt concentrations are low.
10, 133, 159
Effects of
TGase from
Streptomyces mobaraense
on textural properties and water holding in low-salt
meat systems are summarized in Table 12.8.
TGase has not been shown unequivocally to be an adequate salt replacer from the water-
holding viewpoint, but at high enough salt levels ensuring sufficient protein solubility,
TGase is capable of improving both textural and water-holding properties. However, when
salt levels are low (
2% NaCl), introduction of strong cross-links in proteins by TGase
has not generally been found to improve water holding of heated meat systems, although
textural properties have been improved.
128, 132, 133, 155, 159
The reason is most probably the
increased protein-protein interaction and thus reduced protein-water interaction. Due to
≤
