基于高光谱技术的柑橘不同部位糖度预测模型研究

Research on the detection model of sugar content in different position of citrus based on the hyperspectral technology

利用高光谱技术研究柑橘不同部位的糖度预测模型,将花萼、果梗和赤道部位的高光谱信息分别建立与其对应部位糖度的预测模型,建立基于偏最小二乘(Least squares regression,PLSR)、主成分回归(Principal component regression,PCR)和多元线性回归(Stepwise multivariate linear regression,SMLR)预测模型,3种预测模型中PLSR模型检测效果最好,通过Norris derivative预处理方法对花萼光谱数据进行处理后,预测集相关系数r_(pre)=0.950,预测集均方根误差RMSEP=0.636°Brix。结果表明,采用柑橘不同部位的高光谱信息与对应糖度预测模型是可行的,花萼部位所建立模型的效果优于果梗、赤道部位,因此花萼部位可作为优先选择的光谱检测部位,这对于指导实际检测分级生产中柑橘的摆放位置具有重要意义;采用PLSR方法建立柑橘花萼、果梗和赤道部位的高光谱信息与平均糖度的预测模型时,花萼部位模型效果最好,预测集相关系数r_(pre)=0.913,预测集均方根误差RMSEP=0.621°Brix,建模效果相较于对应部位光谱与糖度模型差,因此,采用柑橘全部果肉的平均糖度与采集部位光谱建立糖度预测模型具有一定的局限性。

Hyperspectral techniques were used to study the sugar content of different parts of citrus, and the sugar content detection mod- els with hyperspectral information of calyx, stem and equator part were established respectively. The results showed that the model established by calyx was better than that of stem and equator. The detection models of partial least squares regression （PLSR）, principal component regression （PCR）, and stepwise multivariate linear regression （SMLR） were established respectively, and the results of these three models were close. The PLSR model was found to the best among them, after Norris derivative pretreatment methods were applied, the prediction correlation coefficient （rpre） and the root mean square error of prediction （RMSEP） were 0. 950 and 0.636°Brix. This result inclined that it was feasible to use the hyper-spectral technology to detect the sugar content in different parts. The study indicated that the calyx part could be the prior choice for the sugar content detection site in the citrus quality testing, and the conclusion has great significance for the way of citrus place in the actual production. Moreover, the PLSR method was used to establish the model of hyperspectral information and average sugar content in calyx, stem and equator part. The highest prediction rpre and RMSEP of models was in the calyx and only to be 0.913 and 0.621°Brix, which was nut excellent e- nough. Therefore, it was limited to predict the citrus average sugar content with the hyperspectral information of a certain part.