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SPX Speck Expert - Semolina Application Note

Semolina Speck Counting

Overview
The milling of durum wheat produces a granular product comprised of evenly sized starchy endosperm particles called semolina. Dark specks in semolina adversely affect the appearance of semolina and the finished pasta. Wheat bran is the most common source of brown specks and black specks are caused by discoloured or diseased kernels, weed seeds, ergot or dirt. Speck counting is a mandatory quality control determination which assures the semolina meets customer specifications. Despite its importance, speck counting has been performed using a subjective inconsistent manual counting method.

QA/QC and Production Tool
The SPX is easily calibrated by human counters, and the calibration is transferrable as well as password protected. With guaranteed operator independent speck counts, rapid and repeatable results can be generated at any time of day or night. Archived results and images allow database management of all analyses. As a quality assurance and control tool, it has become the bench-top method of choice for durum millers and pasta manufacturers.

The SPX has become a production tool as well. It is used to identify new wheat stocks that come through the mill since the speck counts will change. This alerts staff and allows for a fast response before problems arise further down stream. It is also used to push extraction rates knowing problems can be identified quickly and solved easily. It is cost effective due to the increased volume of analyses and reliability of speck counts.

Measurement Results
Results of testing 4 commercial semolinas are shown in the graph at right, with an SPX image of specks in semolina at left. Using a range of particle size minimums, the graph illustrates the linear correlation between SPX speck counts and manual speck counts. The 'best fit' between digital and manual counting appears to be at the 180 micron minimum particle size setting. Objective speck counting using this SPX calibration is easily verified and can be tailored to specific product types where fine and coarse product have different speck counting parameters.