Chemical and Functional Properties of Food Saccharides

© 2004 by CRC Press LLC
TABLE 8.2
Catalog of Wheat Flour Requirements for Modern Starch Production for
100 g Flour on a Fresh Weight Basis
Characteristics Limit
Moisture (%) ~15.0
Protein (N conversion factor: 5.7) (% d.b.) ~12.0
Minerals (% d.b.) ~0.63
Lipids (% d.b.) ~1.5
Fibers (% d.b.) ~1.5
Starch (% d.b.) ~80.0
Wet gluten (g) ~28.0
Amylogram peak viscosity (BU) ~500
Falling number (s) ~250
Starch potentiala (%) min. 70
Starch granules < 10 µm (%)
a Determined by the mixer test/wash test.
max. 30
Source: From Bergthaller, W.J., Witt, W., and Seiler, M., Proceedings of the 2nd International Wheat
Quality Conference, Manhattan, KS, May 20–24, 2001, in press.
d.b. = dry basis
BU = Brakender units
s = second
g = gram
8.3.3.2 Dough Preparation and Gluten–Starch Separation
Wheat flour is mixed continuously with water at 32°C to form a stiff dough and to
develop gluten. The cohesive dough formed is allowed to rest to complete hydration
of flour particles and, in particular, gluten proteins. The dough is then mixed vigorously
with additional water to accelerate segregation of gluten from starch. Further
separation of gluten aggregates from starch suspension occurs while pumping the
mixture into the gluten washer, a long, slanted rotating cylinder, the wall of which
is equipped with 40–mesh–plate screens. During passage, water is sprayed via
nozzles on gluten and screens to wash away starch and to avoid plugging of screen
slits. While the mixture of starch, tailings, and fibers is rinsed to an intermediate
tank, gluten is further purified with excess water in a gluten washer. Then gluten
gets dewatered, split up into small pieces, and is simultaneously remixed with dry
gluten powder to prepare for drying in a flash dryer. This final treatment allows
gluten to adapt to drying conditions in a way that allows maximum gluten vitality.
By this process, a dried gluten product results that can be reconstituted into the
original material and is highly functional.
8.3.3.3 Starch Purification, Dewatering, and Drying
The suspension leaving gluten washers is removed of fibers by sieving and purification
with centrifugation and hydrocyclone washing. The first step is the separation
of residual small gluten particles by rotating sieves, shaker sieves, or sieve bends.