NEAR-INFRARED (NIR) SPECTROMETRIC TECHNIQUE FOR NONDESTRUCTIVE DETERMINATION OF SOLUBLE SOLIDS CONTENT IN PROCESSING TOMATOES

A nondestructive method for measuring the soluble solids content (SSC) of individual processing tomatoes (Lycopersicon esculentum Mill.) was developed using NIR spectrometry. A diode array fiber optic spectrome ter was used to measure NIR transmittance. Each fruit was scanned at t wo locations on opposite sides midway along the proximal-distal axis. After scanning, each fruit was processed and pureed, and SSC was deter mined using a refractometer. Multiple linear regression (MLR), partial least squares (PLS) regression, and neural network (NN) calibration m odels were developed using the second derivatives of averaged spectra from 780 to 980 nm, The validation results showed that NN calibration was better than MLR or PLS calibrations. The NN calibration could esti mate the processed SSC of individual unprocessed tomatoes with a stand ard error of prediction of 0.52% and could classify >72% of fruit in a n independent population within +/-0.5% of SSC.