Non-Destructive Qualification of Kiwi-Fruit by Near Infrared Diffuse Reflection Spectrometry

The relationship between quality of kiwi-fruit in maturity and its near infrared diffuse reflection spectra was studied by near infrared diffuse reflection spectrometry and chemometrics. At room temperature of (24±2) ℃ , the NIR spectra in the range of 4 000 to 10 000 cm^-1, from different sites in the equatorial region of each kiwi-fruit were collected and pre-treated by the combined processing of smoothing, normalization and base-line correction. On the other hand, calibration models for hardness and soluble solid contents (SSC) of the kiwi-fruit were established by applying the methods of partial least squares (PLS), principal component regression (PCR) and multiple linear regression (MLR). As shown by the results, the accuracy of the calibration model established by the combined processing of pretreatment and PLS method was the highest. Values of R_c, R_p, RMSEC and RMSEP for hardness testing attained to 0.976 5, 0.946 2, 0.548 3 and 0.612 7, respectively. And values of R_c, R_p, RMSEC and RMSEP for SSC testing were up to 0.916 6, 0.901 2, 0.539 6 and 0.619 0. The feasibility of the method was thus verified.