Location: Sugarbeet and Bean Research
Title: Detection of sucrose content of sugar beet by visible/near-infrared spectroscopy Authors
Submitted to: ASABE Annual International Meeting
Publication Type: Proceedings
Publication Acceptance Date: July 1, 2013
Publication Date: July 21, 2013
Citation: Pan, L., Zhu, Q., Lu, R., McGrath, J.M. 2013. Detection of sucrose content of sugar beet by visible/near-infrared spectroscopy. In: Proceedings of the American Society of Agricultural and Biological Engineers Annual International Meeting, July 21-24, 2013, Kansas City, Missouri. Paper No. 13-1619051. Interpretive Summary: Sucrose content is the most important quality parameter in the production and processing of sugar beet. Currently sugar beet processors rely on destructive methods to measure and monitor sucrose content of harvested beets. Rapid and convenient measurement of sucrose content in sugar beets can assist breeders in selection of promising germplasms and help growers and processors in determining the yield and quality of beets after harvest and during storage and processing. This research evaluated the feasibility of using two portable spectroscopic instruments, covering the spectral regions of 400-1,100 nm and 900-1,600 nm, respectively, for fast measurement of sucrose content from intact and sliced sugar beets. A total of 398 sugar beets from different commercial hybrid varieties, harvested in 2012, were tested in the experiment. Wet lab analysis via high performance liquid chromatography (HPLC) was used to provide reference sucrose content measurements of the beet samples. Calibration models for the spectral data were developed for predicting the sucrose content of the beet samples. Good predictions of sucrose content for sliced beets were obtained with the correlation coefficient of 0.86 and 0.88 for the visible and shortwave near-infrared region of 400-1,100 nm and the near-infrared region of 900-1,600 nm, respectively. Considerably lower correlations were obtained for intact beets. This research demonstrated that it is feasible to measure sucrose content from sliced beets using a low-cost portable spectroscopic instrument. However, further improvements in the sensing configuration are needed in order to achieve satisfactory sucrose content measurements for intact beets.
Technical Abstract: Sucrose content is the most important quality parameter in the production and processing of sugar beet. This paper reports on the application of visible/near-infrared (Vis-NIR) spectroscopy for measurement of the sucrose content of sugar beet. Two portable spectrometers, covering the spectral regions of 400-1,100 nm and 900-1,600 nm, respectively, were used to acquire spectra in interactance mode from both intact beets and beet slices. The sucrose content of beets was measured using high performance liquid chromatography (HPLC). Calibration models for each spectrometer were developed using partial least squares (PLS) to predict the sucrose content of beets. For the spectrometer covering the visible and shortwave near-infrared (Vis-SWNIR) region of 400-1,100 nm, the correlations (Rp) were 0.81 and 0.86, and the standard error of prediction (SEP) were 0.91 and 0.78, for the intact beets and beet slices, respectively. For the NIR spectrometer with the spectral region of 900-1,600 nm, Rp = 0.72 and 0. 88 and SEP = 1.02 and 0.69 for the intact beets and beet slices, respectively. These results showed that the portable spectrometers operated in interactance mode can be used to predict sucrose content for beet slices. This research also identified several important wavelengths that had relatively strong correlation with the sucrose content, for both Vis-SWNIR and NIR measurement, indicating the possibility of using selected wavelengths or bands for predicting the sucrose content of beets.