5. Rye Varieties
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Since 1992 the BSA has issued descriptions of the properties of rye as
well as wheat varieties and updated them where necessary.
The quality attributes of the varieties are described by comparison
with one or more reference varieties. For some time Halo has been the reference
variety. The results of other rye varieties are then shown as a percentage of
this reference variety (= 100%) and divided into categories from 1 to 9.
Category 1 means unfavourable results for an attribute.
The BSA's descriptive list of varieties currently contains 28
varieties of winter rye and three varieties of summer rye. The ratio of pure
breeds to hybrid varieties has shifted continuously in favour of the
higher-yield hybrids since the latter were first approved. The current list
contains 12 pure breeds and 16 hybrids (Fig. 93).
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| Fig. 93: List of German rye varieties, 2002 |
The suitability of rye, and products ground from rye, for making baked
goods raised with sour dough or baker's yeast depends to a large extent on
their composition. Limited enzymolysis is an advantage in processing (Drews
1971a, b). In this respect, rye varieties with a low protein content and high
pentosan levels are said to be advantageous, as are those with low enzyme
activity, particularly α-amylase.
6. Testing Methods for
Describing the Quality of Rye
For a long time the α-amylase activity of rye was thought to be the
only factor limiting suitability for bread making. Sprouted grain is known to
result in bread with a very moist crumb. Weipert (1998a, b) therefore sought to
establish a correlation between α-amylase and Falling Numbers and Amylogram
values. Only in the case of very low or relatively high amylolytic activities
good correlations of Falling Numbers and Amylogram values have been detected.
For a long time, systematic tests to ascertain the fundamental
technical characteristics of rye centred on the Amylogram and Falling Number as
standard methods. Since 1994, consideration has also been given to the total
pentosan content, the percentage of soluble pentosans, the flour yield (in a
standard milling test) and suitability for bread-making (in a standard baking
test using sour dough in a flour of the type 997). In 2002 this procedure was
updated and now includes tests on grains and flour for Falling Numbers, the
Amylogram, the new Rye Viscosity Test after Brümmer (2002) and the standard
milling and baking test.
6.1 Milling Properties
The milling properties of rye varieties are determined in a standard
milling test on a Bühler laboratory mill. The flour yield is assessed in
relation to the mineral content of the most important rye flour types (mineral
content around 1.0% d.b.). Because of the different structure of rye cells,
mechanical damage to the starch grains during milling is relatively low
compared to that of wheat. In the sensory analysis, i.e. when rubbed between
the fingers, rye flours are generally found to be finer and smoother than wheat
flours. Larger proportions of fine grains lead one to expect more rapid water
absorption (swelling) and increased sensitivity, for example to enzymatic
activity. These structural differences are influenced by the nature of the
starch, the proportion of larger and smaller starch granules, the enveloping
function of the hemiculluloses and other factors.
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