Agriculture Reference
In-Depth Information
(2.7 to 3.6 Kg-force) measured on the fruit cheek have
high consumer acceptance and with 9 to 13.5 N (0.9 to
1.4 Kg-force) flesh firmness are considered ready to eat.
at 0°C than at 5°C (Table 10.5). However, market-life
potential is affected by several other factors such as orchard
conditions and maturity. For example, the role of maturity
in market-life potential is well illustrated in our
'Blackamber' plum work (Table 10.6).
Pit burning symptoms are similar to internal browning
but this is a heat damage problem that originates before
harvest of 'Italian' and other cultivars of prunes and plum.
It is associated with high temperatures during fruit matura-
tion and can delay harvest (LaRue & Johnson 1989).
PLUM POST-HARVEST HANDLING SYSTEMS
Fruit deterioration factors
Chilling injury (CI) or internal breakdown (IB)
Chilling injury (CI) is a concern with most plum and fresh
prune cultivars. It is expressed as flesh translucency and is
associated with flesh browning (Plate 10.4). In previous
publications from South Africa, flesh translucency, specifi-
cally in some plum cultivars, has been called 'gel break-
down' (Dodd 1984). In the United States, these symptoms
are reported as 'internal breakdown' or CI (Crisosto
et al
.
1999b; Mitchell & Kader 1989). CI symptoms normally
appear after placing fruit at ripening temperatures (20°C to
25°C) following cold storage at 2°C to 8°C. Postharvest
life varies among cultivars and it is strongly affected by
temperature management. Most plum and fresh prune cul-
tivars are most susceptible to chilling injury when stored at
5°C. Market life of 'Blackamber,' 'Fortune' and 'Angeleno'
plums at 0°C was > 5 weeks. 'Showtime,' 'Friar' and
'Howard Sun' plums developed chilling injury symptoms
within 4 weeks, even when stored at 0°C. In all plum culti-
vars, a much longer market life was achieved when stored
Post-harvest treatments to reduce deterioration
Controlled atmosphere (CA)
The major benefits of CA during storage and shipment are
retention of fruit firmness and delay of changes in ground
colour. Decay incidence can be reduced by CA of 1 to 2%
O
2
+ 3 to 5 % CO
2
. Currently, CA has a limited use for stor-
age for greater than 1 month with some cultivars such as
Angeleno, Casselman, Santa Rosa, Laroda and Queen Ann
(Kader & Mitchell 1998; Truter
et al
. 1994; Ben & Gaweda
1992; Streif 1989; Eksteen
et al
. 1986; Mitchell
et al
. 1981;
Couey 1960, 1965).
The influence of modified atmosphere packages (MAP) on
quality attributes and shelf life performance of 'Friar' plums
was studied on 'Friar' plum (Cantín
et al
. 2008). Flesh firm-
ness, soluble solids concentration (SSC), titratable acidity
Table 10.5
Effects of Storage Temperature on Market Life Potential of Plum Cultivars
a
.
Storage/shipping
potential (weeks)
Cultivar
Plant breeding program
Fruit type
0°C
5°C
Angeleno
Garabedian
Semi-free to freestone
5+
5
Betty Anne
Zaiger
Clingstone
5
5
Blackamber
Weinberger
Freestone
Earliqueen
Zaiger
Clingstone
3
2
Friar
Weinberger
Freestone
5
3
Flavorich
Zaiger
Clingstone
5
5
Fortune
Weinberger
Semi-clingstone
5+
3
Hiromi Red
Zaiger
Clingstone
5
3
Howard Sun
Chamberlin
Freestone
4
1
Joanna Red
Zaiger
Freestone
5
5
October Sun
Chamberlin
Semi-clingstone
5
5
Purple Majesty
Bradford
Clingstone
5
3
Showtime
Wuhl
Freestone
5
3
Information was obtained from personal communications with Gary Van Sickle, Kevin Day, and
David Ramming, from Brooks and Olmos (1972), Whealy and Demuth (1993), Okie (1998), nursery
catalogues and United States Patents.
a
