Food Chemistry

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 mobaraenseis
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
(Mr:37,842) of known sequence. A cysteine
residue is probably at the active center. The

Table 2.23.Possible applications of transglutaminase

Raw Application

material

Meat Restructured meat from small pieces

Partial replacement of cutter aids in the

production of boiling sausage

(“Brühwurst”).

Fish Production of fish gel

(surimi, cf. 13.1.6.11)

Reducing water loss in the thawing

of frozen fish.

Milk 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.

Wheat “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 ap-

preciably 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.............................................

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Anklam, E., Gadani, F., Heinze, P., Pijnenberg, H., Van

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Eur. Food Res. Technol. 214 , 2 (2002)

Baudner, S., Dreher, R.M.: Immunchemische Metho-

den in der Lebensmittelanalytik – Prinzip und An-

wendung. 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 enzy-

matischen 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