[目的]提高近红外光谱技术在线检测柚子糖度的精度.[方法]采用自主研发的柚子在线无损检测设备采集3种光照区域的柚子的漫透射光谱数据,在650～950 nm的波长范围内采用标准正交变量变换(SNV)、多元散射校正(MSC)、归一化(normalize)、SG 一阶求导(savitzky-golay first order derivative,SG-1st)对原始数据进行预处理,使用自适应性加权算法(CARS)筛选反映柚子糖度的光谱特征,建立了偏最小二乘回归(PLSR)模型.使用未参与到建模的30个柚子样本进行在线验证.[结果]光照区域C结合SNV-CARS-PLSR方法的建模效果最优.其预测集的决定系数为0.95,均方根误差为0.30 ° Brix.在线验证时决定系数为0.90,均方根误差为0.58 °Brix.模型对于柚子糖度具有较强的在线检测能力.[结论]在光斑直径为70 mm且位于柚子赤道上方20 mm的光照区域C的条件下采集的柚子光谱数据所建立的预测模型能更有效地实现柚子糖度的在线预测.
Research on influence of light region on near infrared spectroscopy for online detection of sugar content of grapefruit
[Objective J To improve the accuracy of online measurement of sugar content of grapefruit by near infrared spectroscopy.[Methods]The pomelo online non-destructive testing equipment developed by ourselves was used to collect diffuse transmission spectrum data of pomelo in three light regions.In the wavelength range of 650～950 nm,orthonormal variable transformation(SNV),multiple scattering correction(MSC),Normalize,Savitzky-Golay first order derivative,SG-lst preprocessed the original data,used the adaptive weighting algorithm(CARS)to screen the spectral characteristics of the grapefruit sugar content,and established a partial least squares regression(PLSR)model.30 grapefruit samples that were not involved in the modeling were used for online verification.[Results]The modeling effect of light region C combined with SNV-CARS-PLSR method was the best.The coefficient of determination of the prediction set was 0.95 and the root-mean-square error was 0.30 °Brix.In online verification,the coefficient of determination was 0.90 and the root mean square error was 0.58 °Brix.The model had a strong ability to detect the sugar content of grapefruit on line.[Conclusion]The prediction model based on the spectral data collected under the condition that the light spot diameter is 70 mm and the light region C is 20 mm above the equator of the grapefruit can realize the online prediction of the sugar content of the grapefruit more effectively.
near infrared spectroscopylight regiononline detectionsugar contentgrapefruit
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