Letter to the Editor: Wheat hardness affects milling
June 01, 2002
by Emily Wilson
I read the article "Wheat Hardness Affects Milling" (see World Grain, February, 2002, pages 58 to 61; E-Archive #51808). What advice (in terms of % ratio) would you give a miller who intends to blend soft with hard wheat to achieve a better result? What conditioning time would you recommend for such a blend? Soft wheat mills grinding hard wheats often have problems with flour color and flour ash. Why?
NDFM, Umunya, Anambra State, Nigeria.
[Editor:] According to Henry Stevens, director of technical services at U.S. Wheat Associates, the percentage for blending hard and soft wheat depends on the desired end-use characteristics to be achieved and the inherent characteristics of the hard and soft wheat to be blended.
Normally, the percentage is determined by the mill lab or R&D department by running a series of tests on blends of flour derived from the constituent wheats. The series might be 90/10, 80/20, 70/30, etc. The lab then determines which performed best for the intended end use. Depending on the characteristics of the constituents and the desired result, any blend is possible and thus it is impossible to specify which percentage is best for your specific needs.
Normally a blend is tempered for the amount of time most suitable for the harder wheat in the blend if it were to be milled ‘as is.’
One of the differences between a soft wheat mill and a hard wheat mill is that dedicated soft wheat mills have significantly more sifting surface in the flow diagram. This extra sifter surface results in ‘over sifting’ (also known as ‘bare bolting’). When there is excessive sifting, some of the branny particles that normally would be scalped out by the flour cloths can break and then pass through the cloth with the flour. This causes higher ash and darker color in the resulting flour. To help combat this condition in mills that grind both hard and soft wheats, the diagram often uses finer flour cloths (smaller aperture) than would a mill that is designed primarily for either of the constituents ‘as is.’