3. Objectives of Breeding in
Respect of Technical Suitability for Processing as Bread Rye
The BSA21 considers the following criteria important for
rating the suitability of rye for bread-baking:
• Thousand kernel weight (TKW);
• Crude protein content (CPC);
• Peak Amylogram values for viscosity and temperature;
• Results of the Falling Number test.
When assessing new wheat varieties the BSA carries out baking trials:
this is not the case with rye. In contrast to the procedure for baking wheat,
the four criteria stated above were considered an adequate basis for describing
the suitability of new bread rye varieties for baking when the present rating
systems were introduced. This was justified as long as a sufficiently elastic
crumb was the only quality attribute to be achieved in rye bread, an attribute
that was usually guaranteed by adequate enzyme levels in the greater part of
the rye harvest. Rye grain Falling Numbers of about 100 to 120 s or higher –
corresponding to peak Amylogram temperatures of about 63 °C – were considered
necessary to ensure this aspect of processing quality.
4. Rye Quality
In the European Community, rye is defined according to the support
criteria as having a Falling Number of at least 120 s. In Germany the
expression bread rye is still used and defined as having Amylogram maximum
temperatures of at least 63 °C. Peak Amylogram viscosity is not used for
evaluation, but the Falling Number is considered additionally. The rheological
index figures for rye as a raw material are determined using a milled wholemeal
product ground on a defined cross-beater mill, the Falling Number mill. For the
rye flours normally used in Germany, with a mineral content of about 1% (d.b.),
the Falling Numbers for bread rye are about 120 to 130 s and the Amylogram
gelatinization temperatures are 64 to 65 °C.
Increasing Falling Numbers and Amylogram values for rye have
established themselves almost unnoticed, partly because of selection by
breeders and partly as a result of more favourable weather and more accurate
forecasts of the ideal time for harvesting. But the following are further
reasons for the change in the rheological values of bread rye:
• increase in the total pentosan content;
• reduced proportion of soluble pentosans;
• reduced or delayed effect of the amylase naturally contained in the
grains, or of its enzymes;
• shift in the range of varieties towards more high-yield hybrids;
• changes in cropping areas and thus the growing sites for rye;
• specific use of agricultural inputs, especially to increase the
yield;
• great improvements in harvesting techniques;
• greatly improved post-harvest treatment;
• slight changes in the milling process and flour yields;
• certain changes in the tolerances for minerals in classified rye
flour types.
Nevertheless, rye remains a sprout-endangered cereal, and in contrast
to wheat the site on which rye is grown has a greater influence on the regional
harvest result than the variety. (Brümmer, 1999a) A comparison of the years
1960 and 2004 (Tab. 70) shows the typical changes in the various index figures
over the past four decades. Interestingly, the bread volumes have fallen in
spite of the higher values of the indirect methods. (Brümmer 1999b,c).
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Tab. 70: Average changes in the analytical values for rye flours of
the types 997/1150
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Note :
21 Bundessortenamt, German Federal Institute for varieties
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