New Zealand Journal of Crop and Horticultural Science abstracts
Ripening and development of chilling injury in persimmon fruit:
an electrical impedance study
F. ROGER HARKER
SHELLEY K. FORBES
The Horticulture and Food Research
Institute of New Zealand
Mt Albert Research Centre
Private Bag 92 619
Auckland, New Zealand
Abstract Electrical impedance spectroscopy was used to follow
ripening and chilling injury development in persimmon fruit (Dyospyros
kaki L. `Fuyu'). Tissue resistance and reactance were measured at
frequencies between 50 Hz and 1 MHz, and then fitted to an electrical model.
Fruit responses to both ripening at 20deg.C and storage in modified atmosphere
at 7deg.C were distinct and easily detected using electrical impedance
spectroscopy. Plots of reactance against resistance at each series of
frequencies traced a semicircular arc. During ripening, the arcs dilated
between Days 1 and 21, then contracted, until at Day 35 they were smaller than
at Day 1. Electrical modelling indicated that the dilation occurred as a result
of a 43, 115, and 17% increase in resistance R1 (cell wall resistance), R2
(cytoplasm resistance), and R4 (vacuole resistance), respectively. After 35
days of ripening, R1 was 39% lower and C3 (membrane capacitance) was 19% higher
than at Day 1. Chilling injury developed with increasing time at 7deg.C in
modified atmosphere storage (MA), until severe symptoms were observed after 5
weeks. Chill-injured fruit differed from other fruit in that R2 was
significantly lower upon removal from storage, although it rapidly increased
when fruit were transferred to 20deg.C for ripening. These results are
discussed in relation to the physiological changes that occur during ripening
and development of chilling injury in persimmon.
Keywords persimmon; Diospyros kaki; fruit ripening;
chilling injury; electrical impedance
New Zealand Journal of Crop and Horticultural Science, 1997, Vol. 25:
149-157
0114-0671/97/2502-0149 $7.00/0 (c) The Royal Society of New Zealand
1997
PDF file of entire paper: medium quality (652K); (scanned from paper original: notes about this process)
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