Tomatoes - Crop Post-Harvest: Science and Technology - page 16

(Qadir & Hashinaga 2001). However, attempts to use
low O 2 and high CO 2 to improve tomato eating quality
have not been successful (Ratanachinakon et al . 1997).
Atmospheres with ≤ 1% O 2 and/or > 3-5% CO 2 can cause
uneven ripening, uneven colour development, discoloura-
tion, softening and off flavours if exposure times are long
(Kader et al . 1989). Application of heat treatments in low-
oxygen atmosphere did not significantly decrease chilling
injury (Soto-Zamora et al . 2005b; Yahia et al . 2007).

achieved with 2°C storage temperature under active or
passive MAP (Artes et al . 1999).

Pathological disorders
Tomatoes are sensitive to attack by several decay organ-
isms. Tomato losses at the retail and consumer levels in the
New York area were estimated at 11.4-14.2%, and were
mostly due to diseases, principally Alternaria , Rhizopus ,
grey mould ( Botrytis ) and bacterial soft rots (Ceponis &
Butterfield 1979). Most post-harvest decay problems of
tomatoes originate during cultivation. Decay problems are
minor in tomato production in modern greenhouses with
good climate control, but can be more severe in low-
technology greenhouses and field production. Decay can
also be initiated in the packing line due to physical damage
and contamination. Micro-organisms can enter tomato
fruit through openings such as wounds, cracks, cuts, stems
and stem scars. Tomatoes with defects that may provide
entry to pathogens should be separated from good-quality
fruit. Lower grades of tomato, which may have more
abrasions and cuts and larger stem and blossom-end scars
than higher grades, were found to develop higher incidence
of decay and were also more likely to be infected when
inoculated with the causal agent of bacterial soft rot,
Erwinia carotovora (Bender et al . 1992). Chilling injury
augments the incidence and severity of decay in tomato.
The most common decay problems in tomatoes are
described as follows.

Storage of fresh-cut tomato
Fresh-cut produce sales have increased spectacularly
during the last decade, especially in Europe and North
America, mainly due to changes in consumer demand but
also due to improvements in the cool chain and processing
technology, including MAP. Quality and marketability of
tomato slices deteriorate rapidly after cutting compared
with other vegetables, and the effects of slicing on the
post-harvest behaviour of fresh-cut tomato slices includes
a rapid rise in CO 2 and ethylene production, which reduces
shelf life (Artes et al . 1999). A long-life cultivar has been
used for fresh-cut to slow ripening and extend storage life
(Artes et al . 1999). Nonetheless, MAP is considered to
be mandatory as a supplement to temperature control in
order to successfully market fresh-cut tomatoes.
Surface sterilization of whole fruit with sodium
hypochlorite as well as the use of potassium bicarbonate,
calcium chloride and calcium lactate on the slices
extend the shelf life of fresh-cut tomato (Gil et al . 1999).
Most of the defects of fresh-cut tomatoes observed
during processing and storage, such as tissue water
soaking, juice accumulation and moisture condensation,
have been overcome. A water absorbing paper in the
trays prevented juice accumulation (Gil et al . 1999) and
condensation is avoided by the use of anti-fog films.
Water soaking development in fresh-cut tomato slices
appears to be an ethylene-mediated symptom of senes-
cence (Jeong et al . 2004) and not a symptom of chilling
injury as had been suggested. Selecting light red fruit for
processing and avoiding storage above 5°C minimized
water soaking. Lowering the storage temperature was a
more critical factor than MAP in reducing microbial
counts (Gil et al . 2002). High CO 2 and low O 2 concentra-
tions inhibited yeast and mould growth without off-favour
development. The overall tomato slice quality was better
at 5°C than at 0°C under high CO 2 (Gil et al . 2002). After
ten days of storage, the quality attributes of tomato slices
were maintained better at 2°C than at 10°C. When slices
were stored at 10°C, both passive and active MAP
reduced the rate of ripening. The best overall quality was

Black mould or alternaria rot
Caused by Alternaria alternata , the fruit become susceptible
when exposed to <10°C for one week (Plate 2.10). Lesions
are commonly found near the stem scar or at the blossom
end of the fruit. They are flat or sunken, and usually cov-
ered by the sporulating black mycelium of the fungus.
Preventive measures include avoidance of chilling tempera-
tures and avoidance of mechanical injury.

Grey mould
Caused by Botrytis cinerea , it is favoured by cool, moist
growing conditions and mostly occurs on greenhouse
tomatoes, especially if they are film-wrapped. The affected
tissue is usually firm, dry and brown to black in colour
(Plate 2.11). Preventive measures include the use of adequate
storage temperature, the avoidance of chilling and physical
injuries and the use of appropriate pre-harvest fungicides.

Bacterial soft rot
This is caused primarily by Erwinia carotovora subsp.
carotovora , but also by other pectolytic strains of Erwinia ,