2.01 INFRARED ANALYZER

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1 NIR INFORMATION PAGE 1 OF 5 What does it do? First, it allows for better control and knowledge of incoming ingredients. If the ability exists to analyze a truck or rail car immediately upon arrival, the shipment can be rejected if it falls outside of the required specifications. If commodities are purchased on parameters such as protein content, it is possible to get the best price for the necessary material through the use of rapid analysis techniques. NIR allows for the measurement of in-process products. If mistakes are being made in production, NIR can help to rapidly identify out-of-specification material as it is produced. NIR provides results in seconds and allows for adjustment of the process immediately. This ability helps to eliminate rework or scrap product. NIR can help spot trends before the product goes out of specification. How does it work? The term NIR refers to a portion of the electromagnetic (EM) spectrum near the visible and the infrared portion of the EM spectrum.

2 NIR INFORMATION PAGE 2 OF 5 As can be seen, the infrared part of the spectrum is not very large, and the NIR area is even smaller. The NIR region extends from about 750 to 2600 nm (nm = nanometers or 1/ of a meter), and is just on the outside of the visible range. Generally speaking, the interactions of EM waves with matter will simply involve the transfer of energy. A part of the light that was in the original beam was shined onto the sample. Part of the energy is absorbed by the sample. This process is referred to as attenuation. The light then passes through a collimating lens that focuses the light into a more cohesive beam. The light then reaches the filters, which are the wavelength selectors. The filters will allow only a certain wavelength of light to pass through. This process provides the mechanism to measure the absorbance by a sample at a particular wavelength. The wavelengths of the filters have been selected by experiments that have determined at what wavelength protein, moisture, or fat, for example, will absorb. If the sample absorbs some of the light (energy), there will be less light to cause a change in the detector. The light not absorbed by the sample returns and is detected by the detector. All instruments will have some wavelength filters and an energy producer. This is most often accomplished using a light bulb (Tungsten-Halogen lamp). All instruments will have some sort of wavelength discriminator. This will allow the instrument to measure an individual wavelength. It is necessary to have some way of determining the amount of light present. This task is accomplished by the detector.

3 NIR INFORMATION PAGE 3 OF 5 The last feature common to all instruments is some sort of signal processor. The signal processor changes the absorption information received by the detector into a quantitative (ie: the amount of protein) or qualitative result. These features are common to all NIR instruments. Instruments commonly produce what is known as spectra. A spectrum is simply a line that describes how much light is absorbed at different wavelengths. The absorption is proportional to the concentration of a specific constituent like moisture, protein, or fat. The total absorption at a specific wavelength is the sum of the individual constituents absorptions. Calibration The calibration changes the optical information into an understandable form. The calibration is a mathematical transformation. Multiple Linear Regression (MLR) A calibration is a set of numbers that convert the signal from the detector into a predicted value. The first step is to place the sample in the viewing area and press the start button to start the instrument. The lamp is then turned on. A rolling noise is then heard, as the instrument begins stepping through the filters. This is the point at which the instrument is performing a measurement or rather producing and collecting optical data. Each time the filter wheel indexes, a new filter is being moved into the light path. The detector will make a measurement. The number (measurement) that the detector produces is then stored, and the instrument moves the next filter into the light path. The primary requirement of this process is time. The time to collect samples with a wide range of parameter values, and samples with a wide range of manufacturing differences. The objective is to collect the optical information of the samples and then store it to a computer. With current NIR instrumentation, this is only an expenditure of minutes a day.

4 NIR INFORMATION PAGE 4 OF 5 Calibration Samples and Method Creating a Calibration Curve The sample set must span the range of values that could be expected during manufacturing. This means samples from 10 to 16% moisture might be produced. The sample set should contain samples that span the range between 10% and 16%. The sample set should be collected over several days. The set needs to contain a minimum of 20 samples. What is recommended is samples after the first calibration curve, to optimize the accuracy. This will ensure proper statistical validation of calibration coefficients. The sample set should be analyzed in duplicate (blind duplicate if feasible) by the reference method. This helps to screen out lab errors that my occur with single analysis and gives an indication as to the precision of the reference method. NIR is a secondary technique, and the accuracy of the reference method will directly affect the NIR accuracy. The sample set should be stored in air tight containers and in an environment where they will not degrade. ANALYZER VALUES LABORATORY VALUES

5 NIR INFORMATION PAGE 5 OF 5 Calibration Maintenance The goal of calibration maintenance is simple: to maintain calibrations at optimum performance levels. Sample NIR performance should be checked on a regular basis. This means analyzing samples using the reference method(s) of analysis. Suggested schedule consists of checking at least one sample per product per week on all parameters. These weekly checks should be charted in order to observe any trends in the data. One sample out of control limits does not mean that the calibration needs adjusting, however, if three or four are consistently out, it may indicate some adjustments are required. These types of problems can often be overcome with a simple bias and/or slop adjustment. The database will grow quickly and steadily as samples are added on a weekly basis control (a database is a good tool for keeping an instrument performing to its optimum level). Reference Plate The instrument should be checked at least every month with the reference plate. It is only a one to two minute procedure to check the reference plate.