World Grain -- May 2011 - 72

MILLINGOPERATIONS

Wheat Conditioning
Many mixer alternatives available, but all have goal of optimizing wheat uniformity to mill
by Mark Fowler

Most experienced millers understand the importance of a consistent wheat conditioning process. Millers mix water into the wheat in preparation for the milling process to optimize several production variables and maximize the extraction of ﬂour. Conditioning wheat to the optimal milling moisture mellows or softens the endosperm, while toughening the bran. Softening the endosperm increases ﬂour extraction and reduces the power consumption and noise level of the roller mills during the milling process. The proper conditioning of wheat also reduces the ash content and improves the color of the ﬂour produced. Toughening of the bran helps it to remain in larger pieces. Large bran ﬂakes can more effectively be cleaned by the corrugated or ﬂuted rolls utilized in the break system to separate the bran and the endosperm. This reduces the small bran specks in the ﬂour, improving the color and appearance of the ﬁnished product. WHEAT VARIABLES There are many variables to consider when conditioning wheat. Wheat hardness, protein content, ambient temperature in the mill, wheat temperature, moisture content of the dry wheat and target moisture content of the conditioned wheat all effect the time required to properly condition the wheat, and the effectiveness of the method to mix the wheat and the water. Delivering a constant moisture level of wheat to the mill provides constant milling conditions and improves mill balance. Constant moisture level also helps deliver consistent ﬂour moisture to the bakery, which provides more consistent baking conditions. Millers agree that the ultimate goal for any wheat conditioning system is to optimize uniformity of the wheat to the mill. There is much debate over the proper conditioning time; however the need for consistency in mixing is often overlooked. It is important that the quantity of water added is carefully controlled and the adjustment of the
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wheat moisture is controlled and consistent. Critical parts of any conditioning system to achieve consistency and uniformity in the wheat blend must include: • accurate ﬂow measurement for both the wheat and the water; • accurate moisture measurement of the wheat; and • effective mixing of the wheat and water. An important part of the conditioning process is the method used to mix the water and the wheat.
Variable Harder Wheat Higher protein content Lower ambient temperature Lower wheat temperature Lower initial wheat moisture Higher target wheat moisture Effect Longer tempering time Longer tempering time Longer tempering time Longer tempering time Longer tempering time Longer tempering time

MIXER OPTIONS There are many different mixer styles and manufacturers promoting their product beneﬁts. When purchasing a conditioning mixer, the company must make the best decision based on the design requirement restrictions for each speciﬁc installation. Generally speaking, conditioning mixers can be categorized into two speeds — low and high. Both types of mixers, when correctly designed and sized, can add 5% to 7% water in a single stage. Applying and distributing water uniformly to each kernel of grain is an important design consideration for all types of mixers. Water must be evenly distributed on the kernel surface to avoid ﬂuctuating moisture contents due to water migration. Due to the large quantity of grain processed, continuous mixing is most common. For small-scale operations, a batch mixing process can be used. Low speed mixers, such as the Technovator grain conditioning mixer, are continuous mixing conveyors. They are similar to screw conveyors, but with angled paddles. Technovator mixers are installed at an upward angle with the grain inlet at the bottom. The angle of the paddles on the shaft can
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World Grain -- May 2011

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