USING NEAR-INFRARED (NIR) LIGHT TO ESTIMATE THE SOLUBLE SOLIDS AND DRY MATTER CONTENT OF KIWIFRUIT

The use of near-infrared (NIR) light to non-destructively determine the soluble solids content, the dry matter content, and their ratio, for intact kiwifruit is described. Special mention is made of the changes that occur in carbohydrate composition of kiwifruit during storage, and how NIR spectra measured at harvest time may relate to the composition of the fruit at maturity. The electronic and optical hardware used to capture NIR spectra of each fruit is described. We discuss the results obtained using ridge regression and principle component analysis which, to date, have produced the most reliable estimates. We then discuss price and performance of commercially available technology which might be used in an on-line grader to measure internal fruit quality. Finally some indicative costings of a multi-lane grader system are provided, and we describe tests on other crops.