Chemical and Functional Properties of Food Saccharides

© 2004 by CRC Press LLC
volumes in up-to-date production plants. 13 An effective water regime achieved by
the use of hydrocyclones in starch purification was another step forward in process
engineering. More savings in water consumption, finally down to 3 to 2 m 3 , were
achieved with the switch from dough systems to batters or even more diluted flour
water systems, represented, for example, by the Westfalia three-phase decanter
process, and, following this, the separation of starch, gluten, pentosans, and soluble
components by systems based on centrifugal separation. A similar process design
called the Flottweg tricanter process has also been developed. 13 It should be noted
that wastewater load of wheat starch plant effluents is very high and may reach a
specific BOD of 45 kg t −1 and a specific COD of 120 kg t −1 based on a specific
wastewater volume of 2.8 to 3.5 kg t −1 wheat flour. 2
8.3.2 SUBSTRATES
Although in the past specifications for wheat were frequently published as grain
characteristics as, for example, by Witt, 14 industrial practice increasingly considered
flour characteristics only. The standards indicated figures for moisture and
protein content as well as some qualitative and descriptive terms for endosperm
hardness, falling number, and amylograph consistency. Also, principal figures were
presented for proximate composition, comprising moisture, protein, and starch
content as the main components. Minor components such as minerals, lipids, and
fibers were also mentioned. This catalog of requirements does not refer fully to
the actually applied processes, in particular, the modified Martin process and the
Westfalia process.
In the search for technologically important characteristics, wet gluten quantity
as well as the characteristics mentioned previously for grain were still of interest.
New insights established the starch potential and the limit for small-size granules
as additional characteristics in an extended catalog for modern wheat starch manufacture
(Table 8.2). 15
Introduction of centrifugal separation techniques, wheat flours of reduced protein
content, and, to a limited extent, reduced protein quality have been discussed for
application using practical conditions. Even wheat cultivars having a more pronounced
soft endosperm structure have been successfully used in wheat starch
factories. 16
8.3.3 MODIFIED MARTIN PROCESS
8.3.3.1 General Remarks
The modified Martin process 13 is the modern variant of the traditional procedure.
After introducing the necessary improvements, different modifications are still
applied in wheat starch plants worldwide. The improvements include reduction in
fresh water consumption by expanded process water recycling and substitution of
equipment directed toward more efficient starch–gluten separation.