2009_Book_FoodChemistry

2.8 References 155
(2.114)
acid amides and amino acids also react. Proteins
or peptides are cross linked in this way. If amines
are absent, TGase can catalyze the deamination
of glutamine residues in proteins with H 2 Oasthe
acyl acceptor (III in Formula 2.114).
TGases play an important role in the metabolism
of animals and plants. For the production of
protein gels (cf. 1.4.6.3.3), the TGase from the
actinomycete Streptoverticillum mobaraense is
of special interest. In contrast to the TGases from
mammals, the activity of this enzyme, which is
released in large amounts by the microorganisms
into the nutrient medium, does not depend on
Ca 2⊕ . This enzyme consists of 331 amino acids
(M r : 37,842) of known sequence. A cysteine
residue is probably at the active center. The
Table 2.23. Possible applications of transglutaminase
Raw
material
Meat
Fish
Milk
Wheat
Application
Restructured meat from small pieces
Partial replacement of cutter aids in the
production of boiling sausage
(“Brühwurst”).
Production of fish gel
(surimi, cf. 13.1.6.11)
Reducing water loss in the thawing
of frozen fish.
Texture control of low-fat yoghurt
to produce the palate feeling of a
whole-fat product
Increasing the solubility of casein in the
presence of Ca 2⊕ ions or at a lower pH,
e. g., for beverages.
Cross linking of casein with whey
proteins to increase the protein yield in
cheese making.
“Hardening” of soft wheat flour for the
production of pasta.
pH optimum of TGase activity is between 5
and 8. This enzyme can also be used at low
temperatures and is rapidly denatured at 70 ◦ C.
Proteins are cross linked by the formation of
ε-(γ-glutamyl)lysine isopeptide bonds. However,
the biological availability of lysine is not appreciably
reduced. The viscoelastic properties
of the resulting protein gels depend not only on
the type of proteins and the catalytic conditions
(TGase concentration, pH, temperature, time),
but also on the pretreatment of the protein, e. g.,
heat denaturation.
Possible applications of TGase in the production
of food are shown in Table 2.23.
2.8 References
Acker, L., Wiese, R.: Über das Verhalten der Lipase in
wasserarmen Systemen. Z. Lebensm. Unters. Forsch.
150, 205 (1972)
Anklam, E., Gadani, F., Heinze, P., Pijnenberg, H., Van
Den Eede, G.: Analytical methods for detection and
determination of genetically modified organisms in
agrictultural crops and plant-derived food products.
Eur. Food Res. Technol. 214, 2 (2002)
Baudner, S., Dreher, R.M.: Immunchemische Methoden
in der Lebensmittelanalytik – Prinzip und Anwendung.
Lebensmittelchemie 45, 53 (1991)
Bender, M.L., Bergeron, R.J., Komiyama, M.: The
bioorganic chemistry of enzymatic catalyis. John
Wiley & Sons: New York. 1984
Bergmeyer, H.U., Bergmeyer, J., Graßl, M.: Methods
of enzymatic analysis. 3rd edn., Vol. 1 ff., Verlag
Chemie: Weinheim. 1983ff
Bergmeyer, H.U., Gawehn, K.: Grundlagen der enzymatischen
Analyse. Verlag Chemie: Weinheim. 1977
Betz, A.: Enzyme. Verlag Chemie: Weinheim. 1974
Birch, G.G., Blakebrough, N., Parker, K.J.: Enzyme
and food processing. Applied Science Publ.: London.
1981