Cereals processing technology

138 Cereals processing technology
by appearance, taste and volume on cooking. Too low a protein level results in
noodles with a poor cooking performance while too high results in undesirable
brightness loss in both the raw and cooked noodle. Noodle elasticity has been
correlated with protein quality based upon the mixograph test’s time to
maximum bandwidth. A positive correlation between protein content and noodle
firmness has been found repeatedly thus enforcing tight specifications for noodle
manufacturers.
Starch has been shown to be the key component responsible for this unique
noodle texture. Primary starch, the major component of flour, is the
predominant component contributing to the desirable viscoelastic noodle
texture. However, on an equal weight basis, the starch tailings have been
shown to have a significant influence as well. High starch swelling cultivars
are beneficial to the quality of Japanese Udon noodles. They are associated
with the absence of a series isozymes called granule bound starch synthase
(GBSS) located on a single gene on chromosome 4A. As common wheat is a
hexaploid, all three waxy loci can be controlled individually resulting in the
formation of waxy (less than 1 percent amylose), partially waxy, and normal
(22–24 percent amylose) starches. The water-holding capacity of the flour has
been positively correlated with noodle texture. Higher levels of amylose
decrease the water binding capacity of the cooked noodles and reduce
firmness and elasticity.
Heating a starch slurry above 50ºC causes irreversible swelling of the
granules. This forces the linear amylose from the granule and into the
continuous paste matrix. A working model 26 of starch in a noodle proposed that
large, highly swollen granules at the noodles’ surface are enmeshed in a thin
gluten matrix or attached to the matrix by leached amylose. These large
deformed granules fill vacancies on the noodle surface to yield a smooth clean
noodle. Low swelling flours with small starch granules yield cooked noodles
with a rougher surface and a duller appearance due to greater light diffraction.
Within the salted noodle, high swelling starch imbibes extra water forming a
noodle with a softer bite. The lower levels of hot amylose leached from the
granules improves the noodle elasticity as it cools and gels. This imparts the
unique chewiness associated with a Udon noodle. Starch swelling is also
inversely correlated with flour lipid level. 26
Starch damage during milling increases water uptake during mixing,
decreases the breaking strength of the dried noodle and produces an undesirable
darkening of the noodle. 27 Viscograph paste parameters of starches, in particular
breakdown and final viscosity, have been shown to have a high correlation with
quality measurements of Japanese WSN. 28 The lower amylograph gelatinization
temperatures observed for Australian standard white wheat (ASW) have been
suggested as a factor in yielding soft, pliable noodles. 29 Higher wheat PSI
(particle size index) values corresponding to ‘softer’ wheat were correlated with
improved eating quality and noodle scores while elevated wheat protein was
associated with poorer quality.