New Zealand Journal of Crop and Horticultural Science abstracts
Comparison of four new devices for measuring kiwifruit firmness
G. HOPKIRK
J. H. MAINDONALD
A. WHITE
The Horticulture and Food Research
Institute of New Zealand
Mt Albert Research Centre
Private Bag 92 169
Auckland, New Zealand
Abstract Four new methods of measuring kiwifruit
(Actinidia deliciosa) firmness which have been developed in New Zealand
have been compared and evaluated. They are: (1) "SoftSense", developed by
HortResearch, Ruakura, using characteristics of a fruit's bounce to calculate
"dwell time" which varies with fruit firmness; (2) "Softness Meter", developed
by Massey University, Palmerston North, using the rate at which the fruit
surface is deformed by a known load; (3) "KIWIPOKE", a hand-held wand,
developed by Industrial Research Limited, Auckland, using characteristics of a
small ballistic collision against the fruit to give a firmness value calibrated
to equate to a penetrometer reading; and (4) "Massey Twist Tester", a
destructive test, developed by Massey University, Palmerston North, measuring
the force required to rotate a small plate within the fruit flesh. Using
prototypes of the three non-destructive devices, we repeatedly tested the same
fruit as they softened during coolstorage. Additional fruit were used to
compare fruit firmness measured by the four new devices with results obtained
using a standard Effegi penetrometer. The ability of the devices to
differentiate between different lines of fruit, and the ease of operation are
discussed. Although it is clear that a non-destructive method to measure fruit
firmness will have considerable advantages, at present none of the devices
tested can be recommended unreservedly for general use. However, all these
devices are undergoing further development as a consequence of this and other
evaluations.
Keywords fruit firmness; kiwifruit; Actinidia
deliciosa; non-destructive testing; coolstorage; fruit softening
New Zealand Journal of Crop and Horticultural Science, 1996, Vol. 24:
273-286
0114-0671/96/2403-0273 $2.50/0 (c) The Royal Society of New Zealand
1996
PDF file of entire paper: medium quality (940K); (scanned from paper original: notes about this process)
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