Milling Journal - Q3 2008 - (Page 36)

• Flour will give off and take on water from the head space depending on flour and head space air and moisture content. Table II Human Induced Flour Heating/Cooling Events • Blowers transferring flour from mill storage bin to a warehouse storage bin. • Warehouse blowers moving flour from storage bin to truck load out bin. • Aeration of truck load out bin to facilitate drop rate. • Pressurizing truck to transfer into bakery storage bin. • Aerating the bakery bin to transfer to scaling hopper. Generally, these do not increase flour temperature more than 5 to 15 degrees and have little impact on flour moisture or temperature. Uncontrolled Head Space The head space will undergo extreme fluctuations in temperature and relative humidity. Metal is an excellent conductor of the sun’s energy. Even on a cloudy winter day, the driver of a car will find some degree of warmth or energy when getting into a parked car. Cold weather transferred from the grain storage elevator to the mill for cleaning and processing often causes condensation to form on the transfer screw conveyor or drag conveyor as it passes into the mill. ture, and relative humidity increases. Flour absorbs some moisture but not quickly enough, resulting in moisture condensing on the metal wall of the container or bin. This free molecular water provides the high relative humidity or Aw (0.7 to 0.9) needed to support the activation of inherently-present yeast and mold spores. Head Space Management Head space can not be controlled completely during transportation due to short residence time in the truck or railcar. Loading at low temperatures will not control it, as heating and cooling cycles will occur in a multi-day run period. Insulation is too costly to carry at today’s fuel prices. Load out flour when it is within 10 degrees of ambient, at the coolest time of the day when possible. This will allow warmup and cooling to occur more slowly. Don’t load the coolest flour at the hottest part of the day or the hottest flour at midnight when it is getting cool. The environment of flour storage bins is controlled by the physics depicted in the Psychometric Chart shown in Figure 5 on page 37. Minimize temperature-differential flour and head space. • Transfer flour only during the low- At night, depending on how late it is, the car becomes less warm, and by early morning, offers little respite from the cold. There will be temperature cycles in the head space that are at the whim of Mother Nature. During the warm cycle, flour at the top of the bin will tend to warm up and dry out, surrendering moisture to the air above the flour. The warm air has greater capacity to hold the surrendered moisture than the flour, and there will be infinitely more flour mass than air mass. As the container walls cool, the air cools becoming less able to hold the mois- 36 Third Quarter 2008 Response No. 361 MILLING JOURNAL

Table of Contents Feed for the Digital Edition of Milling Journal - Q3 2008

Milling Journal - Q3 2008 Contents Milling News Far West Rice Generates Own Power New IAOM-KSU Resident Courses Theodore "Ted" Korolchuk: Miller of the Year IAOM News New IGP Wheat/Flour Web Site Wheat Tempering and Surfactants New ADM Milling Center 2008-09 IAOM Officers Controlling Condensation International IAOM Meetings Pest Management/Subramanyam 2008 Wheat Crop Quality Report Product Quality/Gwirtz Buhler 2009 Resident Courses Northern U.S. Wheat/Backman Horizon Milling to Close ON Mill 2nd Quarter Milling Production Chilled Rolls Belting Product Reviews Milling News Enrichments Phil Weisenberger Obituary Material Handling Pneumatic Systems Mixers Roller Mills Roll Corrugation Product Reviews Storage Transportation Equipment Product/Service Directory Ad Index

Milling Journal - Q3 2008

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