Quality control plays an important role in every stage of the production of maize products, from intake to packing.
Large mills have fully equipped laboratories where routine quality checks are carried out. However, the small miller cannot afford to equip and run such a laboratory, and therefore needs an area in the mill where the simpler, basic tests can be carried out.
Here, we focus on the granulation test:
GRANULATION TEST
Although the granulation of products such as samp, maize rice and maize grits are fairly uniform throughout the industry, that of meal products vary from area to area. Some areas of Africa prefer a coarse meal while others prefer a finer flour.
Therefore, when investing in a mill, the correct machine should be ordered and set up with commissioning to produce the required granulation preferred by customers in the area.
By doing regular granulation tests on the final product, one could also pick up problems in the mill, such as rolls grinding too hard and burst or damaged sieve covers. These problems could have an adverse effect on the granulation of the meal.
Equipment
The following laboratory equipment is needed:
- A suitable laboratory sifter
- Hand-held sieves
- Laboratory scale
Method
- Weigh out 100g of the sample to sieve test.
- Use a selection of different size mesh sieves to suit the granulation of your products. It’s always better to have the sieves clothed in micron sizes than in mesh per inch, as the micron size is more accurate.
- Ensure that each sieve that’s placed in the laboratory sifter has a small cube sieve cleaner to keep the apertures of the sieve clean.
- Sieve for 5-10 minutes depending on product.
- Weigh off the stock on top of each sieve as well as the fines in the sifter pan.
An example of covers used for conducting a sieving analysis
| Product | Sieve size in microns | Specification* | Result obtained |
| Super refined - coarse granulation | 1200 | Less than 5% | |
| 700 | More than 30% | ||
| 500 | Balance | ||
| Thro's | Between 20% and 30% |
*Dependent on season
Frequency of test: At least twice per shift. At Roff, we are passionate believers in African entrepreneurs. Our free profit calculator tool for maize milling entrepreneurs has been designed to help you calculate your success and minimise your risk.
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