Application of near Infrared Spectroscopy in the Sugar Industry

Abstract

Raw materials, technological processes, intermediers and by-products of sugar industry have been characterized by near infrared (NIR) spectroscopy. Various sample preparation and spectroscopic methods were compared in order to optimize the measurement conditions of different types of samples. Sugar beet quality parameters were investigated in raw and deep frozen brei form and it was concluded that dry matter and sugar content of samples can be detected with good accuracy (SD = 0.3 – 0.4%) using standard thawing method and special sample holder. Inspite of big sample set (N = 200) with broad variation in alpha-amino nitrogen it was not found acceptable correlation between spectroscopic data and alpha-amino nitrogen content of sugar beet. Raw and purified (filtered, saturated) thin and thick juices and diluted massecuites were investigated using transmission method respectively. Brix value (dry matter) and sugar content, as well as colour of juices were measured with acceptable accuracy but the calibration of purity value showed high standard error. Selected and combined calibrations were developed for six different technological intermediers in three different factories. Chemical composition of molasses (Brix, sugar content, purity) were also measued by NIR using an optimalized sample preparation method. It was concluded that some of the conventional analysis methods (ICUMSA) can be substituted with NIR measurements where a significant reduction was observed in dangerous reagents (lead acetate) and labour-costs.