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Effect of sucrose particle size on NIR spectra

One of the main challenges of food science and technology is to obtain precise information about the food products that are on the market and their production process. NIR (near infrared) spectroscopy has become increasingly important non-destructive analytical technique in food science and technology to provide online monitoring of production process and give information on final product.Use of spectroscopy in the NIR region provides a wide range of applications for controlling the quality of intermediary products and final products. The aim of this research was to investigate the possibility of using NIR spectroscopy for sorting of different particle sizes of sucrose. Experiments were conducted on commercially available white sucrose. Commercial sucrose was milled using pestle and mortar to obtain different particle sizes at an ambient temperature of 22 °C and 43 % relative humidity. Fractions of different particle sizes ranging from 10 μm to 1000 μm were collected by sieving and monitored in the near infra red range. Each fraction was placed in a small metal vessel for NIR sampling and the probe of NIR instrument was leaned upon the sample with the probe slightly touching the sample. NIR spectra were collected over the range of 904-1699 nm using a Control Development, Inc., NIR-128-1.7-USB/6.25/50µm wth installed Control Development software Spec 32. The technique of NIR spectroscopy is based on the electromagnetic absorption at the near-infrared region but the spectral analysis has to be assisted with various chemometric techniques. For that reason NIR spectra were recorded in Excel format and imported to STATISTICA v.8 software for evaluation. The original spectra by Savitsky-Golay "smooth" algorithm for data filtering were imported. Analysis of the spectrums by principal component analysis (PCA) for sample clustering revealed that different particle sizes resulted in different spectrums which opens the possibility of using NIR spectroscopy for in line monitoring of the milling process of sucrose and possibly other food powders with a well defined chemical composition.

NIR; sucrose; PCA; particle size

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