Milling Journal - Q4 2008 - (Page 10) Tempering Soft Wheat Ohio researchers look at the factors that affect flour quality This article is based on a presentation by Edward Souza, research director for the U.S. Department of Agriculture-Agricultural Research Service, Soft Wheat Quality Laboratory, Wooster, OH (330-263-3891). Souza conducted the research described in the article along with colleages Meera Kweon and Ron Martin (retired) at the Wooster station. He spoke in September at a joint meeting of the Ohio Valley, Wolverine, and Niagara districts of the International Association of Operative Millers in Columbus, OH. Tempering is a key step in the flour milling process. It hydrates grain in order to reduce the energy required to mill it and to reduce the shattering of bran fractions that increases flour ash content, thus lowering flour quality. The American Association of Cereal Chemists (AACC) official methods for soft wheat tempering recommend a moisture level of 14%, as wheat comes out of the tempering bin, for maximum quality. Most milling studies, however, have focused on optimizing flour recovery (yield) rather than flour quality. Research Methods The team at the Soft Wheat Quality Laboratory set out to test varying tempering treatments to determine which would result in the best flour quality. The researchers came up with a factorial design for evaluating 16 different treatments using the following factors: • 12% final moisture. • 14% final moisture. • Three hours tempering time. • 24 hours tempering time. • Temperature 25 degrees C (roughly 80 degrees F). • Temperature 45 degrees C (120 degrees F). • 7% initial grain moisture. • 10.2% initial grain moisture. The researchers tested three different soft wheat cultivars – Severn, Cyrus, and Roane – treated as random effects for the purpose of statistical analysis. Flour yield was evaluated using a Quadrumat advanced milling system. Flour quality was evaluated using AACC methods. Results Table 1 (above left) analyzes the variance of tempering factors’ effect on milling yield. The chart shows that the main 10 Fourth Quarter 2008 MILLING JOURNAL
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