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).
Tab. 70: Average changes in the analytical values for rye flours of the types 997/1150
Note :
21 Bundessortenamt, German Federal Institute for varieties


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