712 15 Cereals and Cereal Products
Table 15.40.Concentration of SH- and SS-groups in
flour of different wheat cultivars
Cultivar SH SS SS/SH
μmole per g flourKolibri 1 .15 12. 510. 9
Caribo topfit 0 .88 12. 213. 9
Strong Canadian wheats 0 .95 13. 414. 1
Inland wheat Ia 0 .75 10. 213. 6
Inland IIa 1 .05 12. 612. 0
Canadian Western Red Spring
Wheat (CWRS) 1 .26 12. 910. 2
aMarketed flour blendings.
cultivar, Table 15.41). Gluten swelling power
is assessed by asedimentation valueas recom-
mended byZeleny.In this test, flour is suspended
in an aliquot of a mixture of lactic acid (3.8g),
isopropanol (200 ml) and water (800 ml). The
higher the volume of the sedimented gluten and
starch, the better should be the baking quality of
the flour.
Table 15.41.Baking quality data of some wheat flours
Wheat cultivara
Monopol Nimbus Maris
HuntsmanProtein (% dry matter)b 13. 211. 611. 8
Wet gluten (%) 35. 124. 734. 3
Farinogramc
Water absorption (%) 59. 254. 859. 8
Dough development time (min) 5. 01. 02. 0
Dough stability (min) 5. 01. 50. 5
Mixing Tolerance Indexd(FU) 30 80 130
Extensograme
Area (dough strength, cm^2 ) 143 75 17
Resistance of the dough to extension (EU) 700 680 110
Extensibility (mm) 170 92 100
Baking test
Dough surface somewhat wet to normal normal wet, gluey
Dough elasticity normal somewhat short weak
Baking volume (ml) 738 630 510
aWheat cultivars with breadmakingquality corresponding to very good (“Monopol”), average (“Nimbus”) and
poor (“Maris Huntsman”).
bFactor N× 5 .7.
cExplanation in Fig. 15.26; dough consistency: 500 FU.
dMeasured after 10 min in Farinogram units (FU).
eExplanation in Fig. 15.29.
For a given wheat cultivar, grown under similar
climatic and soil conditions, the baking volume
correlates with theprotein contentof the flour
(Fig. 15.24). A similar linear relationship is not
readily attainable for flours from different culti-
vars, as evidenced by the very different slopes of
the regression lines.
The parameters involved here are those described
in Section 15.2.1.4 as responsible for the prop-
erties of gluten. These include type, amount,
and degree of polymerization of the HMW and
LMW subunits of glutenin as well as the ratio
gliadin/glutenin.
On the whole, the structure of wheat gluten
has been so far evaluated to be able to describe
variety-specific differences in the technological
properties.
Wheat cultivars differ in the content of theirthiol
anddisulfide groups(Table 15.40). This implies
that the stability of a dough may be strongly
influenced by a SH/SS exchange between a low
molecular weight SH-peptide and gluten pro-
teins. This also implies that a positive correlation