The SMRI-NIRS Technology
What is NIRS?
Near-Infrared
Spectroscopy (NIRS) is an analytical technique that uses the near-infrared
region of the electromagnetic spectrum (wavelength range from 800 to 2500 nm). The SMRI uses this technology to provide
information on the composition of sugar process streams. With the SMRI-NIRS Technology,
a dilute factory stream sample is irradiated with near-infrared light. A detector measures how much of each
wavelength of the near infrared light is absorbed by the sample. Different factory
streams will absorb different amounts of each wavelength.

The graph of this
absorption is known as a spectrum.
Translating the NIRS spectrum
The absorption spectrum is too complex to be used to directly derive information about the factory stream composition. Instead, chemometrics (a type of statistical analysis) is used to compare the complex spectrum to a set of NIRS calibrations developed using the same type of samples. It is then possible to determine the analyte composition of factory sample. The SMRI-NIRS Technology calibrations have been developed over many years and contain many thousands of samples analysed at the SMRI in its accredited facilities resulting in accurate, precise and robust predictions. The calibrations are constantly being maintained and validated. This picture shows the ability of the calibrations to accurately predict pol in mixed juice across a wide range of samples from both diffusers and milling tandems (conventional analysis results vs NIRS analysis results).

What is included?
The technology covers all factory process streams (front end, boiling house and final molasses). These include, but are not limited to, mixed juice (MJ), clear juice (CJ), syrup, massecuites, molasses, magmas and remelts. Analytes predicted include brix, pol, ash, sucrose, glucose, fructose, colour and pH for all streams with an additional analyte (dry solids) for final molasses. The availability of analyte results not normally available within the factory environment offers the sugar technologist the opportunity to understand factory processes better and develop controls that were previously unavailable.
Advantages of the SMRI-NIRS Technology
The technology uses a simple dilution method removing the need for additional treatments (such as filtration and the use of clarifying agents) and multiple instruments to generate a complete analyte profile of your factory stream sample. This is shown in the following graphic comparing conventional and SMRI-NIRS Technology analysis methods. The NIRS results are available in less than one minute from one instrument whilst the complete range of conventional analysis depicted here will take days requiring a wide range of expensive instruments.
Applications
The provision of analytes not commonly available to factory personnel allows for a number of results that can aid the process staff. These include:
Weekly stocktake reporting
NIRS analysis provides for sucrose reporting directly into weekly reports. This eliminates the use of pol values which are known to not represent the true sucrose in low purity products. Direct comparison of the pol values of high and low purity products can be misleading and result in decisions that lead to sucrose loss without staff realising.
SMRI-NIRS Technology Toolboxes
In parallel to the development of the technology, the SMRI has developed a range of Toolboxes to help the sugar technologist. Combinations of NIRS analyte results are calculated to help highlight problem areas where there may be a loss of product. These include:
Centrifuge losses: Using NIRS sucrose, glucose, fructose, ash and dry solids, C-centrifuge TPDs can be determined on every centrifuge on every shift.
Inversion losses: Using NIRS sucrose, glucose, fructose and brix allows the monitoring of possible losses, across evaporator trains for example. The system also allows for monitoring of rapidly changing process parameters and the resultant effects on product quality.
Require more information?
If you require more information about how the SMRI-NIRS Technology can help you in your factory please contact queries@smri.org
For equation licensing enquires please contact nirs@smri.org
If you are interested in finding out more about this technology and what it can do for you, please read the following:
Description of the Technology
Walford S (2019). The SMRI NIRS-Technology. Part 1. Development and validation of the technology. Proc Int Soc Sug Cane Technol 30:66-75. https://smri.sharepoint.com/sites/kb/ISSCT/2019-66.pdf
Madho S and Barker B (2019). The SMRI-NIRS technology: improving factory performance. Proc Int Soc Sug Cane Technol 30:76-88. https://smri.sharepoint.com/sites/kb/ISSCT/2019-76.pdf
Walford S (2019). Near infrared spectroscopy: rethinking the possibilities of sugar factory control. Proc 18th Int Conf Near Infrared Spectrosc., Copenhagen, Denmark. Ed by S.B. Englsen, KM Sorenson and F. van den Berg. pp129-134. https://www.impopen.com/nir2017
Practical use of the Technology in the factory
Dairam N, Ramaru R, Ngema S, Sutar N and Madho S (2016). Sucrose losses across the Gledhow evaporators determined using NIRS predictions. Proc S Afr Sug Technol Ass 89:391-405. https://sasta.co.za/download/6/2010-2019/472/2016_dairam-n-et-al_sucrose-losses-across-gledhow.pdf
Gounden T and Walthew D (2018). NIRS as a tool for improved process monitoring. Proc S Afr Sug Technol Ass 91:350-356. https://sasta.co.za/download/6/2010-2019/616/2018-gounden-t-and-walthew-d-refereed-paper-nirs-as-a-tool-for-improved-process-monitoring.pdf
Gounden T, Chili C, Nala S, Suliman M and Rambakus Z (2019). Conversion of the Felixton mill laboratory from conventional to NIRS analysis. Proc S Afr Sug Technol Ass 92:387-397. https://sasta.co.za/wp-content/uploads/2020/01/2019-Gounden-T-et-al.-Refereed-Paper.-Conversion-of-the-Felixton-mill-laboratory-from-conventiona.pdf
User Testimonials:
“Tongaat Hulett implemented NIRS across the South African mills from the 2019 season. NIRS was deployed at the central refinery during the 2020 season. The implementation of NIRS was trouble free and the efficiency of the laboratory reporting system significantly enhanced. NIRS enabled additional analyses measurements to be taken that have been used to improve the management of factory operations." ~Tongaat Hulett Sugar
“The changeover from conventional chemistry to NIRS has not been an easy change to implement, however it has been worth the effort. Not all benefits have been realised as yet as we bed down the technology, however this is a long term, forward looking change and the benefits will certainly accumulate in due course." ~Illovo Sugar (South Africa) Pty. Ltd.