'Foreign Material Control in Flour and Grist Mills, a National Park Service document, circa 1970.
A grist mill powered by a water turbine. Note the wooden penstock and the belts driving the millstone spindles and elevators. Illlustration from Poole & Hunt Catalog, Baltimore, Maryland, 1900.
"Much of our national illness is caused by crazes for food that is (1) white, (2) refined, (3) keepable. All three crazes are exemplified in white flour. The best food chemists are the earth and the sun, which produce the whole-wheat that the steel rollers of the white flour millers spoil. White flour make white faces........food is stuff to be eaten fresh, not to be "kept" as if it were an heirloom........wholemeal flour naturally does not "keep" because the germ in it is alive. Germless white flour "keeps" because it is dead, because it is as dead as Portland cement powder, all its original goodness having been sifted out of it. Let them "keep" their flour who have no care to keep their health," Ellen and Vrest Orton, "Cooking with Whole Grains," Farrier, Straus, & Giroux inc., New York, 1951.
Foreign Material Control in Flour and Grist Mills Most of foreign material which reaches the finished product was originally in the raw material (what or corn), an adequate check of ingredients at the time of arrival is necessary. But foreign material may also reach the ingredients or mixtures after their arrival and during production. Therefore, subsequent storage and handling of wheat and corn and other ingredients in the process of manufacture must take place with such care that foreign materials are unlikely to be incorporated, even accidentally. 1. The best way to determine the presence of foreign material in the raw material is to obtain a sample and examine it under a microscope. This type of examination may not be possible in a small operation or small mill. 2. Visual Examination of Incoming Ingredients. It is important that all shipments of incoming wheat and/or corn be properly examined at the time of receipt; preferably before they are brought into the bakery (or mill). The examination should consist of checking for contamination on the outside as well as on the inside of the individual bags. The examination of the outside of the bags should be made immediately after the car, truck or other vehicle is opened, because many insects do not like the light and will tend to crawl into cracks or between bags or cartons where they cannot readily be found. If there is evidence of live insect infestation on or in the bags being received then the shipment should be rejected. The bags should also be checked for rodent damage. Select at random at least 4 bags and obtain samples from each bag. Check these samples for insects, foreign material and rodent contamination. If more than one live or dead insect is found or if any foreign material of filthy origin is detected, the lot should be considered for rejection. EXAMINATION OF SIFTER TAILINGS Insect eggs may pass undetected through the wheat or corn and develop full grown larvae or worms while it is held in the mill in the form of flour. Therefore, it is important that a check of the tailings from the flour handling equipment sifter be made each day. This check should be made by sifting the tailings through a large thirty mesh screen and checking for insects or other foreign materials. Whole wheat flour can be examined by taking a two pound sample from each of flour bags. Sift as much as will go through a thirty mesh screen, transfer the residue (consisting most of bran) and distribute evenly on a large place of white paper. Examine the material closely for signs of insects or other foreign material (extraneous filth). Cracked wheat is to coarse to sift so it should be checked by one pound samples and spreading them out thinly on a large sheet of white paper under a strong light and examining them for sings of foreign material. STORAGE PRACTICES Proper storage of all raw materials, packing materials, and other supplies is important in good foreign material control. Adequate storage ensures that the raw material will not become contaminated while awaiting use. Ideally, all bags, cartons, or other package, if not perfectly clean, should be brushed at the time of arrival. They should be neatly stacked on clean skids or pallets and placed in storage. The storage area should be clean, treated with a residual insecticide. If mice are a problem suitable traps should be set. An eighteen inch boarder should be painted about the perimeter of all storage areas. The skids or pallets should be stored eighteen inches from all walls and, if space permits, a fourteen inch aisle should be left between double rows of skids. This method of storage will permit sweeping under skids. If space does not permit this ideal method of storage, all materials should be moved at least monthly. This is the only sure way of avoiding the creation of a harborage area. Experience has shown that the eighteen inch space between stock and walls is more important than the fourteen inch aisle between double rows of skids or pallets. Therefore, if space does not permit proper storage, the aisle may be eliminated, but the space between stock and walls should remain. PACKAGING MATERIALS Packaging materials such as bags or cartons used to package the finished product should be protected from all foreign material both in storage and during use. Such packaging materials and other supplies should receive the same care and treatment in storage as the ingredients. The point is that any materials left unmoved for more than a month may develop an insect or rodent infestation. DUST CONTROL Successful storage depends in a large measure on the degree of dust control. Where a dust problem does exist, it is usually a problem in only one part of the mill. In dusty areas store only those items which are used up rapidly. FLOOR DIRT CONTROL In the handling of stored materials in and out of the storage areas, it is important that the bags and other containers be kept off the floor at all times; to avoid the transfer of flour dirt from flour to bags. The practice of shaking the empty bag over the receiving container will result in dust entering the container. Unless the exterior of bags is kept perfectly clean, the transfer of an dirt on the exterior of the bag into the product is must likely. PRODUCTION PRACTICES You will note that the entire sanitation program seeks to eliminate insect and rodent activity from the premises so that there will be no chance of these filthy elements of foreign material reaching the finished product. Production employees should have a sanitation consciousness to prevent the contamination of the finished product. Foreign material such as flour dirt, greasy particles, pieces of paper bags, string, slivers of wood and numerous other particles should not get into the finished product.
Equipment......................................................Frequency Flour Handling Equipment.............................Each three weeks. Sifters.............................................................Weekly. Mixers.............................................................Daily. Ingredient Containers.....................................Dry- every 3 weeks, wet- daily. Dust Systems................................................3 weeks. Floors............................................................Daily. Scale Pits.......................................................2 weeks. Elevator Pits..................................................3 weeks, 2 weeks if damp or wet. Pipes & Overhead Structures.........................3 weeks. Walls..............................................................Rough walls every 3 weeks, others as needed. Floor Drains...................................................Weekly. Sump Pits......................................................4 weeks. Windows.......................................................3 weeks - glass cleaned as needed. Electrical Fixtures..........................................4 weeks. Ceilings..........................................................As needed. Lockers..........................................................4 weeks.
1. SELECTION OF GRAIN.
"From Wheat to Flour," (1966) Edition, Wheat Flour Institute, Chicago, Illinois.
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