Miller Magazine Issue 110 / February 2019

56 COVER STORY MILLER / FEBRUARY 2019 flours. A set of graduated sieves will allow you to per- form a size distribution analysis on any sample of flour. Specks: Small fragments of foreign matter. Hair, feces, rubber, cotton, etc. They show in a visual inspection. Foreign matter: A set of sieves may catch some fo- reign matter, but for flours (as everything is milled) you must use chemical digestors and then analyze the results with a microscope. That’s the way to recognize hairs, eggs, excrement and many other small things. Starch content: It is the most important parameter for flours. You get it with a NIR analyzer or with an enzy- matic test. Starch damage: Sprouting or faulty storage can lead to starch damage. That means the baking quality of the flour decreases. This parameter is analyzed with a Falling Number test. Starch gelatinization: You need a special microscope, or birefringence, with polarized filters. This analysis me- asures the quantity of gelatinized versus native granules. Protein content: Most of the time it is measured with a NIR. The standard test is the Kjeldahl analysis. It is one of the most important parameters for animal feed. Fat content: In the several stages of oil extraction you have to check the fat content. It also has value in the subproducts that are later sold as animal feed. You can measure it with a NIR or (more precisely) with a Soxhlet apparatus. Ash content: Basically, you burn all the stuff comple- tely. Ashes of a complete combustion are not coal, but the mineral residue (inorganic materials) that remain af- ter all the organic substances turn into smoke. For flour, ash content determines the whiteness, which itself do- esn’t mean much, but consumers want it. The laboratory is a key piece of the Operations Ma- nagement in a mill or an elevator. The grain must be inspected through all its processing stages, until it turns into a bun. As Peter Drucker said, “if you want to change somet- hing, first you have to measure it”. The laboratory is the heart of the continuous improvement efforts. At every stage of the process you have to check the values of the parameters that you care the most. Let’s say you manufacture animal feed. For that purpo- se, you have some whole grains (corn) that you mill your- self, some subproducts (sunflower expeller) of other in- dustries, and some additives (minerals and vitamins). It is very important to learn how to take samples. There are many books on the subject and maybe I will wri- te a couple of articles about it in the future. Meanwhi- le, understand that quality control doesn’t mean 100% analysis. Not even 10%. The size of the samples and the frequency of the sampling varies according to the prob- lems you encounter. If everything goes fine, you check less. If a problem arises, you increase the frequency. You have to check the quality of the grain (moisture, foreign matter, specific weight, protein and fat content) and of the subproducts (fat and protein content, foreign matter). The equipment for that is basic and cheap. For the supplements you have to either ask for a qua- lity certificate or get a third-party lab to control the qu- ality for you. Unless you are a major miller, the cost of having your own technicians and equipment for that is not justified. Then you clean, dry, and store the grain. That is pro- cessing. So, you have to check the quality of the grain again after it. Most people only check when they receive and they miss invaluable information on the efficiency of their processes. Milled subproducts are only stored, but the quality of the conservation has to be controlled. In theory, you should check them at reception and only right before use, if they have been stored for a long time. Storage, as a process, should be controlled with spaced repetition. Start checking them after one month, and then adjust if you find problems or everything is ok. If you find rodent feces, for example, apply some treatment and increase the frequency of the controls. If everything is ok, check after two months. Supplements are only checked at reception, unless you fully trust the certificates of the supplier. It is a good idea to hire a third-party lab to conduct the analysis as it is easier than setting up your own lab for that. You may check them again before use, but it doesn’t make much sense. Just keep an eye on the expiration dates. Later, every stage of the process (grinding, mixing, pel- leting, etc.) causes some kind of change in the products. Here you have to take samples to see how the relevant properties are affected by the process. Did your process get contaminated? Did the heat affect the proteins or the vitamins? Any change shown in those numbers will tell you where to look for a problem or an opportunity. Once you have a solid understanding of your processes and how they affect your parameters, you have everyt- hing set for an improvement plan. Good luck. Note: If you want to know more about laboratory analysis of grains, be sure to check “Cereal Grains: La- boratory Reference and Procedures Manual”. It is a great book by Sergio Serna.