New Zealand Journal of Crop and Horticultural Science abstracts
Effects of cooling treatments and physical damage on tip rot and postharvest
quality of asparagus spears
N. LALLU
C. W. YEARSLEY
H. J. ELGAR
The Horticulture and Food Research
Institute of New Zealand Ltd
Private Bag 92 169
Auckland, New Zealand
email: Nlallu@hort.cri.nz
Abstract The effects of postharvest cooling rates and
physical damage to tips, on the incidence of tip rot and other quality
attributes of asparagus spears (
Asparagus officinalis L. `New
Zealand Beacon Syn 2'), harvested early and late in the season, were
investigated. The half cooling times were 1
1/2 min, 1
1/2
h, and 5
3/4 h for hydrocooled, forced-air cooled, and passively
cooled spears, respectively. Apical tissue cooled more rapidly than middle and
basal zone tissues. Incidence of tip rot, and visible quality and toughness of
asparagus spears, was not affected by the method of cooling, or delays after
harvest of up to 12 h at ambient temperatures before hydrocooling.
However, overall spear quality was marginally higher, and weight loss
significantly less, in hydrocooled spears than in forced-air or passively
cooled spears. It is recommended that spears are hydrocooled or forced-air
cooled within 4-12 h of harvest. In this study, the incidence of tip rot
was not linked to the time of harvest within a season. Incidence of tip rot
increased with increasing severity of non-visible impact damage to spear tips.
Impact on apical tissues after drops from 0, 50, 100, and 150 mm resulted
in 0, 34, 36, and 64% tip rot, respectively, after 5 days at 20deg.C and 93-95%
relative humidity (RH). Washing spears after impact increased the incidence of
tip rot. Although adverse physiological stress may be a factor involved in the
expression of tip rot, results indicate that physical damage may be a major
contributing factor, exploited by micro-organisms present on the asparagus
spears and in packhouse wash water, leading to spoilage.
Keywords asparagus; Asparagus officinalis L.;
hydrocooling; forced-air cooling; passive cooling; impact damage; tip rot;
postharvest quality; storage
H99012
Received 13 April 1999; accepted 17 November 1999
PDF file of entire paper: medium quality (795K); (scanned from paper original: notes about this process)
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