Agriculture Reference
In-Depth Information
pentosan or arabinoxylan materials from various
plant sources.
Solvent retention capacity characteristics have
been most often associated with cookie baking
attributes of soft wheat, but individual SRC tests
are not strongly predictive in all circumstances.
In one study involving single cultivars across
environments, individual SRC tests accounted
for no more than 59% of the variation in sugar-
snap cookie diameter (Guttieri et al., 2002). In
the same study the narrow range of kernel texture
values precluded a signifi cant correlation between
SC-SRC and SKCS hardness index. Since the
SRC tests were designed as a group they might
best be considered as a group in order to provide
the most helpful profi le of a fl our sample. Gutt-
ieri et al. (2001) used multiple regression to
account for 78% of the variation in cookie diam-
eter using only Su-SRC and fl our protein content.
Using the same sample set these authors used
cluster analysis to show that larger-diameter
cookies could be made from fl ours with both low
and high W-SRC, but larger diameter required
low values for both SC-SRC and Su-SRC. Also
moderately large cookie diameters were achieved
by fl ours with low to moderately low W-SRC,
SC-SRC, and Su-SRC but with relatively high
LA-SRC. At the other end of the scale the cluster
with the lowest cookie diameter was unambigu-
ously differentiated from the others by high
values for all four SRCs. Ram et al. (2005) used
multiple regression analysis to account for 83%
of the variation in farinograph water absorption
using W-SRC, Su-SRC, SC-SRC, and grain
protein content. The group of 192 genotypes
used in that study varied in W-SRC from 53%
to 71%, suggesting a mix of hard and soft kernel
texture.
Additional solvents or variations on the theme
of the SRC tests have already been suggested.
These include a suggestion by Bettge and Morris
(2001) that a sequential SRC test might enhance
differentiation among cultivars. They suggested
water followed by ethanol followed by lactic acid,
sequentially exposing fl our to each solvent in
turn, without drying the pellet between SRC
determinations. More developments are expected
with the investigation of further additional solu-
tions including those containing reducing agents
and SDS (Miklus et al., 2004).
DOUGH TESTING AND PREDICTION OF
DOUGH PROPERTIES
It is diffi cult to approach the subject of measuring
dough properties without repeating what has
been thoroughly reported and reviewed in the
past 70 years. The older tests covered in this
section have been the stalwarts of commerce
and research in wheat for decades and show no
signs of becoming any less utilized. This is
despite some clear limitations of these older
techniques and vigorous efforts to fi nd better
and faster ways of measuring or predicting dough
characteristics.
SDS sedimentation volume
Determination of SDS sedimentation volume is a
widely used method, particularly for coarse
screening of dough strength potential in breeding
programs. The test is based on the principle that
gluten proteins swell in dilute lactic acid solution
and that larger proteins—those related to higher
dough strength—sediment more slowly and are
associated with higher sedimentation volume.
The test comes in a number of variants, and the
newer variants are primarily adapted for stronger-
gluten wheat or for microscale tests (AACC
approved methods 56-60, 56-61A, and 56-63,
AACC 2000). Actual SDS sedimentation volumes
are highly dependent on fl our protein content, so
dividing the result by the fl our protein content
provides a corrected SDS sedimentation volume
per unit protein, and a useful comparison of
dough strength potential among samples. Indeed
some breeders consider the raw SDS sedimenta-
tion volumes to be of little value, but use the
protein-corrected volumes to identify lines with
weaker dough attributes that, for example, may
contain the 1RS·1BL translocation (B.F. Carver,
pers. comm.).
