Dielectric power spectroscopy as a potential technique for the non-destructive measurement of sugar concentration in sugarcane

• Great potential of dielectric power spectroscopy for sensing the sugarcane quality.
• Accurate predictions of °Brix, %Pol and water content by dielectric power spectra.
• A potential technique for nondestructive measurement of sugarcane quality.

One of the existing serious technical challenges in the sugarcane industry is the lack of a low cost technique for the non-destructive measurement of sugar concentration as °Brix (percent soluble solids) or %Pol (percent sucrose) from either standing sugarcane in the field or sugarcane stalk/internode samples in laboratory. This study aimed at investigating the potential of dielectric power spectroscopy as a simple technique for this purpose. A parallel-plate capacitor was developed and supplied with sinusoidal voltage waves swept within a frequency range of 0–10 MHz where the consumed power of the capacitor was monitored as a function of frequency by a spectrum analyser. Seventy five internode samples from four sugarcane cultivars were measured by the dielectric sensor and then analysed for °Brix and %Pol in laboratory. Multiple linear regression (MLR) models were developed for prediction of °Brix and %Pol as functions of dielectric power at the swept frequencies with R2 > 0.99 and RMSE < 0.31. The water content of the internode samples was also strongly predicted by the dielectric power spectra with a RMSE of 0.17%. It was concluded that dielectric power spectroscopy can be implemented as a potent and simple technique for the non-destructive measurement of °Brix and %Pol of sugarcane.