Spatial variability of soluble solids or dry-matter content within individual fruits, bulbs, or tubers: implications for the development and use of NIR spectrometric techniques.
Peiris K. H. S., Dull G. G., Leffler R. G., Kays S. J.
Author Affiliation: Department of Horticulture, The University of Georgia, Athens, GA 30602-7273, USA.
HortScience 34 : 114-118
Abstract : Spatial variation in soluble solids content (SSC) of apple (cv. Red Delicious), cantaloupe melon, grapefruit (cv. Indian River Ruby Red), honeydew melon, mango (cv. Hayden), orange (cv. Valencia), peach (cv. Windblow), pineapple (cv. Kew) and tomato fruits and onion bulbs, and in dry matter content (DMC) of potato (cv. Russet Burbank) tubers, was measured along 3 directional orientations (proximal to distal, circumferentially midway along the proximal to distal axis, and radially from the centre of the interior to the outer surface). The pattern and magnitude of constituent variation depended on the type of product and the direction of measurement. Radial and proximal to distal variation was greater than circumferential variation in all the products tested. Honeydew melon fruits had the highest radial variation with a SSC difference of 6.0% and a cv of 22.8%, while tomato fruits displayed lower radial variation with a cv of 1.0%. Pineapple fruits had a proximal to distal SSC difference of 4.6% with a cv of 13.8%, while the difference in tomato fruits was 0.6% with a cv of 5.1%. Circumferential variation of SSC in all products tested was 2% with cv ranging from 1.1% to 3.8%. The results confirm that considerable constituent variability exists within individual fruit and vegetable organs. This variability may affect the accuracy of calibration equations and their prediction capability. Therefore, within-unit constituent variability should be meticulously assessed when an NIR (near infrared) spectrometric method is being developed for the non-destructive quality evaluation and sorting of a product.