A Comparison between Reflectance, Transmission and Interactance Modes of NIR Spectroscopy in Non-Destructive Moisture Content Determination of ‘Mazafati’ Date Fruit

Document Type : Research Paper



A non-destructive, rapid and low-cost determination of date fruit moisture content is one of the most determining factors in maturity assessment and processing of this valuable product. On the other hand, the potential of Near Infrared (NIR) spectroscopy in nondestructive internal quality evaluation of agricultural products has been proved throughout several studies. In this research, three modes of near infrared spectroscopic measurements namely, reflectance, transmission and interactance, were compared for their ability to non-destructively estimate moisture content of ‘Mazafati’ date fruits. Spectral acquisitions were carried out through a photo-diode array (PDA) spectrometer in the range of 900-1700 nm. The spectra were then smoothed through Savitzky-Golay algorithm and preprocessed by Multiplicative Scatter Correction (MSC) method. Finally, the Partial Least Squares (PLS) regression method was applied to develop moisture content predicting models in each mode. The results indicated that the interactance mode provided the most accurate estimates of moisture content with a coefficient of determination (Rcv2) of 0.922, Root Mean Squares Error of Cross Validation (RMSECV) of 1.57% and Residual Predictive Deviation (RPD) of 3.60. The reason for this priority could be due to the lower level of such irrelevant information as distance variation of sample and probe and as well due to the lower effect of surface irregularities in the interactance mode.