Direct near infrared analysis of sugar cane clear juice using a fibre-optic transmittance probe

Determination of sugars in sugarcane juice is an important task in sugar refineries as well as in food industries because of its continuous evolution during the fermentation process. A rapid and accurate method for the determination of total sugars, also termed as the 'Pol' value, using a near infrared (NIR) fibre optic probe has been developed and validated. Clear sugarcane juice samples were collected from the sugar industry during the entire sugarcane season to represent a wide range of concentration of components such as sucrose, glucose and fructose. The samples were scanned in the NIR region (5400-6400 cm^-1) using the fibre-optic transmittance probe and analysed by partial least squares (PLS). The standard polarimetric method was used to obtain reference values for the calibration model from NIR results. The calibration model developed was able to assess the Pol value in unknown sugarcane clear juice samples accurate to an R² value of 0.936. The technique has potential in the rapid measurement of Pol content in sugarcane clear juice for the sugar industry.