基于漫透射光谱技术的番茄可溶性固形物及总糖含量的无损检测

为了满足果蔬品质快速安全无损检测,基于可见-近红外漫透射原理,设计了番茄专用环形光源,自行搭建了番茄可见-近红外漫透射多品质检测系统,并以可溶性固形物含量(SSC)和总糖(TS)作为内部品质指标,对58个番茄样品进行了快速无损检测研究。基于自主搭建的系统对每个番茄进行四点的光谱采集,对平均后的光谱分别用15点SG卷积平滑(SG-Smooth)、标准正态变量变换(SNV)、多元散射校正(MSC)、一阶导数(FD)等方法进行了预处理,分别建立了SSC及TS的偏最小二乘预测模型,并对该模型进行了验证。结果表明:采用15点SG平滑预处理后的SSC预测模型校正集和预测集相关系数分别为0.995 6和0.976 0,均方根误差分别为0.052 4°Brix和0.082 3°Brix。采用SG平滑后一阶导数预处理的TS预测模型校正集和预测集相关系数分别为0.969 1和0.972 9,均方根误差分别为0.423 8%和0.454 9%。模型验证结果显示,番茄SSC和TS模型预测结果与标准理化值相关系数分别为0.985 5和0.944 9,均方根误差分别为0.066 3°Brix和0.571 5%。利用自行搭建的可见-近红外漫透射光谱检测系统完全可以实现番茄可溶性固形物及总糖含量的快速无损预测,为番茄内部品质的评价提供了实时、无损、快速的检测方法,为其在线分级提供理论基础。

Determination of Tomato’s SSC and TS Based on Diffuse Transmittance Spectroscopy

In order to meet the demands for rapid and safe nondestructive testing of fruit and vegetable quality,tomato detection system with a special circular light source was built based on the visible/near infrared diffuse transmission principle.Taking soluble solids content (SSC)and total sugar (TS)as the internal quality index,the prediction of 58 tomato samples was carried out by using this system.First,we collected the spectral data of four points for each tomato.Second,Savitzky-Golay smooth (SG-Smooth),standard normal variable transformation(SNV),multiplication scattering correction(MSC),first derivative (FD) and other methods were used to process the original spectral curve before the partial least squares regression(PLSR)model was established.Finally,we validated the established model.The results show that the correlation coefficient (r)of calibration and prediction of the SSC prediction model-are 0.995 6 and 0.976 0 when using 10 point SG-smooth,and the root mean square error of calibration and prediction are 0.052 4% and 0.082 3%.The partial least square regression (PLSR)model,with respect to the first derivative (FD)spectra,provides better prediction performance for total sugar of tomato,with correlation coefficient (r)of calibration of 0.969 1 and 0.972 9,and prediction,root mean standard error of 0.423 8% and 0.454 9%.In the experimental verification of the prediction model,the relationship of SSC between predicted and true value is 0.985 5,root mean square error is 0.066 3°Brix,the relationship of TS between predicted and true value is 0.944 9 while root mean square error is 0.571 5%. The results show that the content of soluble solids and total sugar in tomato can be realized by using visible/near infrared dif-fuse reflectance spectroscopy.It provides a real-time,nondestructive and rapid detection method for the evaluation of the internal quality of tomato,and provides a theoretical basis for its online grading.