便携式双档位柑橘多品质无损检测装置设计与试验

A portable dual-gear device for non-destructive testing on multi quality of citrus

为了解决普通检测装置难以覆盖不同果径(25~95mm)柑橘的检测需求问题,研发了覆盖多果径柑橘的便携式双档位多品质无损检测装置。以砂糖橘(果径25.35~48.61mm)和武鸣沃柑(果径53.24~94.71mm)为研究对象,基于研发的双档位探头,在赤道部位每隔120°采集一次光谱,平均光谱作为该柑橘的原始光谱。经标准正态变量变换(standard normal variable,SNV)、多元散射校正(multiplicative scatter correction,MSC)预处理,再利用竞争性自适应加权抽样算法(competitive adaptive reweighted sampling,CARS)筛选特征波长,分别建立了沃柑和砂糖橘的可溶性固形物含量(soluble solids content,SSC)和水分的偏最小二乘预测模型。沃柑的SSC和水分预测模型验证集相关系数分别为0.937、0.951,均方根误差分别为0.382°Brix、0.491%;砂糖橘的SSC和水分预测模型验证集相关系数分别为0.921、0.935,均方根误差分别为0.460°Brix、0.673%。为了评估检测装置的准确性和稳定性,使用平均变异系数分析了沃柑和砂糖橘的SSC含量和水分测定结果,并通过预测结果与标准理化值进行残差分析。结果表明,研制的便携式双档位柑橘多品质光谱检测装置对不同果径柑橘内部品质检测稳定性与精度均满足现场实时检测需求。

Rapid and non-destructive testing is of great significance for the quality grading in the citrus industry.This study was focused on the actual needs of on-site real-time detection on the internal quality of citrus fruits with different fruit diameters(25-95mm)in China.The spectral variation coefficient of citrus fruits was determined with different fruit diameters at the same point.A systematic investigation was made to explore the impact of the incident light angle on the spectral information of citrus fruits.A dual-gear probe was then designed for the local diffuse transmission spectral acquisition.A portable non-destructive testing device was developed for the internal quality of citrus fruits with multiple fruit diameters.Four modules included a light source,a spectrum acquisition,a control and display,as well as a power supply module.The size of entire device was 160mm×80mm×65mm,weighing 390g.Taking sugar orange(fruit diameter 25.35-48.61mm)and Wuming Wo orange(fruit diameter 53.24-94.71mm)as the research objects,the spectra were collected every 120°at the equator using the dual range probe,and then the average spectrum was used as the original spectrum of the citrus.Competitive adaptive weighted sampling(CARS)was used to filter feature wavelengths after preprocessing with standard normal variable transformation(SNV)and multiple scatter correction(MSC).A partial least squares(PLS)prediction model was established for the soluble solids content(SSC)and moisture content of citrus.The correlation coefficients of the SSC and moisture prediction model validation set for Wogan were 0.937 and 0.951,respectively,with the root mean square errors(RMSE)of 0.382°Brix and 0.491%,respectively;The correlation coefficients of SSC and moisture prediction model validation set for sugar orange were 0.921 and 0.935,respectively,with the RMSE of 0.460°Brix and 0.673%,respectively.A real-time analysis and control software was written for the device using C/C++language in the QT development tool.One click,real-time,and nondestructive testing was achieved in the multiple qualities of citrus fruits with different diameters.Finally,the experimental verification was conducted on the stability and accuracy of the developed device.The results showed that the average coefficient of variation of SSC and water content predicted by the device for Wogan were 0.024%and 0.022%,respectively;The average coefficient of variation(CV)of SSC content and water content in sugar orange were 0.014%and 0.020%,respectively;The maximum absolute residual values of SSC and moisture device predictions and standard physicochemical values for Wogan were 1.15%and 1.37%,respectively,while those of sugar orange were 1.71%and 1.58%,respectively.Therefore,the portable dual-gear device can fully meet the requirements of on-site and real-time spectral detection on the multiple quality of citrus,particularly for the stability and accuracy of internal quality detection of citrus fruits with different fruit diameters.