2009_Book_FoodChemistry

1.4 Proteins 87
Fig. 1.59. An outline for two- and single-step plastein
reactions. (according to Yamashita et al., 1979)
Fig. 1.58. Production of plasteins with high tyrosine
and low phenylalanine contents. (according to Yamashita
et al., 1976)
Incubation of protein with peroxidase/H 2 O 2 /catechol
also results in cross-linking. The reactions in
this case are the oxidative deamination of lysine
residues, followed by aldol and aldimine condensations,
i. e. reactions analogous to those catalyzed
by lysyl oxidase in connective tissue:
Table 1.44. Amino acid composition (weight-%) of
plasteins with high tyrosine and low phenylalanine contents
from fish protein concentrate (FPC) and soya protein
isolate (SPI)
Amino FPC FPC- SPI SPIacid
Plastein Plastein
Arg 7.05 4.22 7.45 4.21
His 2.31 1.76 2.66 1.41
Ile 5.44 2.81 5.20 3.83
Leu 8.79 3.69 6.73 2.43
Lys 10.68 10.11 5.81 3.83
Thr 4.94 4.20 3.58 4.39
Trp 1.01 2.98 1.34 2.80
Val 5.88 3.81 4.97 3.24
Met 2.80 1.90 1.25 0.94
Cys 0.91 1.41 1.78 1.82
Phe 4.30 0.05 4.29 0.23
Tyr 3.94 7.82 3.34 7.96
Ala 6.27 4.82 4.08 2.56
Asp 11.13 13.67 11.51 18.00
Glu 17.14 27.17 16.94 33.56
Gly 4.42 3.94 4.88 3.89
Pro 3.80 4.25 6.27 2.11
Ser 4.59 3.58 5.45 4.67
(1.164)
Table 1.45 presents some of the proteins modified
by peroxidase/H 2 O 2 treatment and includes their
ditryrosine contents.
1.4.7 Texturized Proteins
1.4.7.1 Foreword
The protein produced for nutrition in the world
is currently about 20% from animal sources
and 80% from plant sources. The plant proteins
are primarily from cereals (57%) and oilseed
meal (16%). Some nonconventional sources of
protein (single cell proteins, leaves) have also
acquired some importance.