Agriculture Reference
In-Depth Information
Table
.
Average maturity indices for some apple and pear cultivars at the optimum
maturity stage
Titratable
DFFB Firmness
Skin
TSS
acid
Starch Seed
(days)
(kg)
colour (%)
(g
/
g)
%
colour
Apples
'Gala'/'Royal Gala'
.
. .
.
.
.
'Golden Delicious'
.
. .
.
..
'Starking'
.
..
.
.
.
'Granny Smith'
.
..
.
. .
Pears
'Williams' B.C.'
.
..
.
'Packham's
.
.
.
.
Triumph'
'Forelle'
.
. .
.
DFFB
=
days from full bloom. Firmness with an . mm diameter plunger for apples
and a . mm one for pears. Skin colour (background) from
=
dark green to
=
yellow.
TSS
=
Total Soluble Solids. Starch
=
% white surface. Seed colour on a scale from
to
.
From van der Merwe (
a). Reproduced with permission.
The general objective in storage is to slow down the ripening process. Fruit
firmness throughout the storage period is largely predetermined by its level at
harvest ( Johnson and Ridout,
). Many of the most important approaches
to improvement of texture after storage are those which improve texture at
harvest. Sugar and acid concentrations after any given length of storage are
also functions of those at harvest, while the development of aroma and those
aspects of ripening consequent on rates of respiration and ethylene synthesis
are very much influenced by factors already in place at the time of harvest.
The control of pre-harvest as well as post-harvest factors is therefore essential
to quality retention and development.
Three areas of fruit physiology provide the basis for most of the technologies
for optimizing quality at any particular time. These are respiration, ethylene
production and action, and nutrition, especially calcium nutrition but also
including the supply of other mineral elements and carbohydrates to the fruit.
Some of these are also involved in the post-harvest and post-storage ripening
which has to be induced for some pears.
As well as being subject to progressive changes in eating quality, apple and
pear fruits are also subject to disorders arising in a more localized way within
the fruit pre-harvest or arising in response to specific, otherwise desirable,
