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.