World Grain - December 2024 - 48

MILLING OPERATIONS
Maximizing flour
extraction rates
Operational monitoring can improve performance
by Jeff Gwirtz
A measure of performance for the transformation of raw or
dirty wheat purchased to produce a unit of flour sold often
is referred to as extraction rate or dirty wheat yield. It is the
measured units of wheat required to produce a measured unit
of straight grade or total flour produced and sold. The units of
measure include commercial bushels of dirty or raw wheat to
produce a hundredweight (100 pounds) of straight grade flour
(bushels of wheat/cwt flour) or alternatively tonnes of raw or
dirty wheat needed to produce a tonne of straight grade flour.
The quantity of wheat and its value identifies wheat cost
per unit of product sold and delivered to the customer. It is
assumed that mill byproduct generated will be equal to the
difference between the wheat and flour weight and has a value
in the market. The cost of wheat less the byproduct credit reflects
the cost of goods sold or material cost whether in bulk
or packaged as specified by the customer.
Knowing the cost of goods, the mill owner must establish
a gross margin based on estimated run time and efficiencies.
Gross margin considers the cost of the transformation process,
which includes direct variable manufacturing costs such as electricity,
labor, packaging, etc., as well as fixed costs that incur
independent of mill operation such as loan retirement (principal
and interest), insurance, etc. The gross margin also includes
gross profit sufficient to cover management expenses and taxes
while providing return to the mill owner(s) as net profit.
A simplified mill budget example for pricing is shown in
Figure 1 (page 50).
Considerable effort goes into establishing a flour sales price
based on the knowledge or estimate of dirty wheat yield. As
extraction rates improve over time and milling margins grow
ever smaller, an understanding of flour extraction and its
management become even more critical. An article from the
January 2018 issue of World Grain (www.nxtbook.com/sosland/wg/2018_01_01/index.php#/p/64)
identifies extraction
improvements over time in the US market as well as reasons
for the improvements, including both agronomic practices,
machinery improvement and shifts in consumer preference.
48
The improvements identified are not isolated to the United
States but have affected the global wheat industry, perhaps to
varying degree. It is important to understand that not all countries'
milling industries have control over wheat purchase decisions
and maybe even flour pricing, making understanding
operational monitoring of the wheat transformation process
even more critical in ensuring milling business continuity.
Dirty wheat yield data is affected by many functional centers
in the milling operations site as shown in Figure 2 (page
50). The performance of any wheat purchase can be dramatically
influenced by both technical and economic decisions at
each functional center as product - either feed or flour - is
delivered to the customer.
Flour extraction can be based on several bases, including
dirty wheat to the mill, wheat to first break, total products
from the milling operation, all wheat in and all milled product
out. Some of these bases have utility in monitoring performance
in milling site functional areas while others convolute
functional area performance issues.
In this article, we will consider how dirty wheat yield or extraction
impacts cost of goods in the primary functional centers
within the milling process, including cleaning, tempering
and milling. We will identify control points for millers managing
the transformation process and remind upper management
of critical details that must be considered when using dirty
wheat yield or extraction values.
Wheat cleaning
The milling center holds little in-process storage. Often scales
or flow balances are not considered for monitoring milling
center system performance but rather rely on the difference in
rate or weight measurements. For example, dirty wheat may
be measured coming into the cleaning house with clean wheat
being scaled or monitored as it passes to the tempering system.
The difference between dirty and clean wheat is assumed to
be screenings. Alternatively, screenings may be measured and
clean wheat to tempering estimated or calculated by difference.
December 2024 / World Grain / World-Grain.com
https://www.nxtbook.com/sos http://www.World-Grain.com
World Grain - December 2024

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