Flour milling with flexibility

by Teresa Acklin
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Eight-roller mill stands and new flour blending system allow Spillers mill to meet U.K. demand for specialty flours.


   A U.S.$6.3-million investment program recently completed by Spillers Milling at Tilbury, U.K., has produced one of the most flexible flour milling operations in Europe.

   In a break with the traditional method of blending wheat before processing, the new production system blends flour after milling. This makes it easier to meet the growing demand for a wide range of specialty flours for different end uses. Spillers Milling, which is the third largest flour miller in the U.K., has particular strengths in producing functional flours and chapati flour and is the largest supplier to the independent bakery sector.

   Built on land reclaimed from marshes beside the Thames river alongside the Port of London Grain Terminal, the mill is the latest of Spillers' seven production units to be completely remodeled. Initially commissioned in 1970, the mill was taken over by Spillers in 1972.

   The basic design was unconventional and innovative. Grain bins and finished product bins were housed together in a single block while the manufacturing unit was installed with open plan floors — a concept which produced savings in both capital and operating costs.

   But the most significant change was the original flour blending system. A unique feature for its time, the system was capable of weighing flours and ingredients to a high degree of accuracy prior to batch blending.

   An ongoing program of improvements has been carried out over the past eight years. This has included the installation of new sifters and a 450-tonne flour storage bin block between 1987 and 1989. Over the next two years the company installed four 175-tonne wheat bins and a Buhler high-speed packing plant fed by four 30-tonne bins capable of packing, stitching and palletizing 600 bags per hour.

   In the latest improvement program, the mill itself has been updated with Buhler's newest Airtronic eight-roller mill stands. The eight-roller mills are capable of two break or reduction passes in quick succession, eliminating intermediate sifting. A process control computer automatically adjusts the milling gap, enabling the miller to achieve the highest possible levels of flour consistency.

   The new flour blending system gives the Tilbury mill a high degree of operating flexibility. Base grists are milled to base flours with precise, measured specifications. The base flours can then easily be blended without affecting the main milling operations and are available in bag or bulk to meet customer requirements.

   In the quality control process, near infrared equipment is used on-line to measure protein, moisture, water absorption and color. After milling, samples are sent to the laboratory for further analysis, and the approved base flours are stored in blending bins ready for mixing. After blending, the flours are checked again against specification and, where necessary, sent for test baking. This ensures the product is tested in use to assess overall blending quality, crumb texture, color and eating quality.

   The Tilbury mill, with some 100 employes, produces and distributes wheat flour to customers in south and east England covering East Anglia, the East Midlands and the South East.

   Diane Montague owned and edited the U.K.'s leading agribusiness trade weekly, Agricultural Supply Industry, for 22 years. She sold ASI in 1992 and now concentrates on freelance writing and consulting.