|PAN, LEIQING - Nanjing Agricultural University|
|ZHU, QIBING - Jiangnan University|
|TU, KANG - Nanjing Agricultural University|
Submitted to: Postharvest Biology and Technology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/22/2015
Publication Date: 3/1/2015
Citation: Pan, L., Lu, R., Zhu, Q., McGrath, J.M., Tu, K. 2015. Measurement of moisture, soluble solids, and sucrose content and mechanical properties in sugar beet using portable visible and near-infrared spectroscopy. Postharvest Biology and Technology. 102:42-50.
Interpretive Summary: Sucrose, soluble solids and moisture content are important traits for sugar beet in breeding selection, postharvest storage, and sugar processing. Moreover, the mechanical properties of beets also have important implications in the design and use of harvest, postharvest handling and processing equipment. The methods currently used to measure these traits or property parameters are destructive or time-consuming, and hence not suitable for evaluating a large number of beets. This research was intended to measure sucrose, soluble solids and moisture content and mechanical properties from whole beets and beet slices, using two portable visible and near-infrared spectrometers covering the spectral regions of 400-1,100 nm and 900-1,600 nm, respectively. Three hundred and ninety eight beets collected from Michigan Sugar Company’s official variety trials in Frankenmuth, MI were used in the experiment. Reference measurements for the property parameters of the beets were made using standard destructive tests. The spectral data acquired for both intact and sliced beets by the two spectrometers were used to develop calibration models for prediction of the property parameters of beets. Both spectrometers gave excellent predictions of moisture, soluble solids and sucrose content for sliced beets with the correlation coefficients of 0.89-0.95. However, prediction accuracies for intact beets were lower, with the correlation coefficients of 0.75-0.85. Poor results were found for predicting the mechanical properties of beets. This research showed that portable visible and near-infrared spectroscopy is potentially useful for rapid assessment of multiple property parameters of sugar beets at harvest and during postharvest handling and processing.
Technical Abstract: Visible and near-infrared spectroscopy, coupled with partial least squares regression, was used to predict the moisture, soluble solids and sucrose content and mechanical properties of sugar beet. Interactance spectra were acquired from both intact and sliced beets, using two portable spectrometers covering the spectral regions of 400-1,100 nm and 900-1,600 nm, respectively. Both visible and short-wave near-infrared (400-1,100 nm) and near-infrared (900-1,600 nm) spectrometers gave excellent predictions for the moisture, soluble solids and sucrose content of beet slices with the correlations of 0.89-0.95 and the standard errors of prediction (SEP) of 0.60-0.85. Lower prediction accuracies were obtained for intact beets, with the correlation values of 0.75-0.85 and the SEPs of 0.88-1.23. However, the two spectrometers showed a poor ability of predicting the mechanical properties of both beet slices and intact beets. Using simple correlation analysis, we also identified wavelengths that had strong correlation with the measured compositions of sugar beets. The portable visible and near-infrared spectrometry is potentially useful for rapid assessment of the moisture, soluble solids, and sucrose content of sugar beet at harvest and postharvest handling and processing.