Agriculture Reference
In-Depth Information
Table
.
Rates of respiration (l CO
/
kg/day) of some common cultivars of
apple: autumn apples only
Cultivar
Respiration rate
'Delicious'
'Golden Delicious'
'Jonathan'
'McIntosh'
'Bramley's Seedling'
-
'Cox's Orange Pippin'
-
Data on respiration under the recommended
post-harvest storage conditions (low temper-
ature, controlled CO
and O
) for each cul-
tivar (from Fidler, ).
◦
Cor
Cultivars showing physiological disorders at very low temperatures (
-
less) show increased respiration at such temperatures.
The rate of deterioration in storage can be determined if the respiration
rate is known (Findlay and Combrink,
). The storage life is related to
temperature by the equation
k
e
−
.
t
φ
=
where
φ
is storage life in days,
k
is a constant for the specific cultivar (
for
for 'Granny Smith') and
t
is temperature (
◦
C). 'Starking', for
example, will become mealy or senescent in
'Starking',
◦
C but takes
weeks at
-
◦
C.
For many cultivars storage life can be prolonged to the maximum achievable
by temperature control, by cooling all the way down to just above the tissue
freezing point. This is usually between
weeks to do so at
−
◦
C depending on the
total soluble solids or sugar content. Cooling has rather less potential for
some other cultivars because they suffer from physiological disorders induced
at temperatures below, for example,
−
◦
C and
◦
C so cannot be stored at lower
temperatures. Precise temperature regimes often reflect locality and cultural
factors as well as cultivars.
It is essential that apples and pears are cooled as quickly as possible after
harvest. A delay of one day at
-
◦
C after harvest reduces the potential storage
◦
Cby
life at
days.
Fruit firmness in store is a function of fruit storage temperature throughout
the period of storage. Given similar initial firmness, an apple stored at
-
◦
C
◦
Cfor
◦
Cfor
will be as firm after
days as one stored at
days or at
days (Fidler,
).
