Agriculture Reference
In-Depth Information
11
Soft Fruit
Leon A. Terry
be briefly reviewed. Since the overwhelming majority of
post-harvest research has been conducted on strawberry,
much of the information presented in this chapter refers to
the post-harvest physiology, biochemistry and pathology
of this important crop. Where appropriate, however, post-
harvest issues for other soft fruit species are discussed.
Soft fruit is a generic category of edible fruit that includes
most berries, currants and the strawberry. Of these, the
most economically important soft fruit are strawberries,
raspberries and currants, respectively (Table 11.1). As their
name suggests, soft fruit are characterised by their innate
lack of firm texture. This attribute alone poses significant
and particular difficulties for the post-harvest maintenance
of quality in terms of handling, transportation, distribution
and shelf life. Furthermore, soft fruit are inherently prone
to post-harvest disease, primarily caused by
Botrytis
cinerea
Pers. (Terry
et al
. 2004). Due to the difficulties
associated with post-harvest deterioration of soft fruit
quality, the majority of soft fruit production is destined for
the processing market. This chapter will, however, only
discuss post-harvest aspects associated with the fresh soft
fruit market.
Refrigeration (< 5°C) during transportation and storage
is the fundamental means used to extend post-harvest life
of soft fruit through retarding fruit softening, senescence
and suppressing disease incidence and severity. This
chapter will discuss other conventional methods of main-
taining soft fruit quality, such as controlled atmosphere
(CA) storage and modified atmosphere packaging (MAP),
which have and are being increasingly adopted by the
industry. In addition, the chapter will also focus on recent
advances in extending post-harvest life through biological,
chemical and physical elicitor treatments of natural disease
resistance (Terry & Joyce 2004a). The effect of manipulat-
ing pre-harvest conditions on fruit quality and future
developments in genetically transformed soft fruit will also
ORIGINS AND ECONOMIC IMPORTANCE
Soft fruit are grown in all temperate regions of the world.
Their importance as a valuable horticultural commodity is
evident in that over 5.5 million tonnes (MT) are produced
annually (FAO 2003; Table 11.1). The commercial
strawberry (
Fragaria
×
ananassa
Duch.), belongs to the
Rosaceae family. It is a perennial herb with rooting runners
that usually bears red-coloured berry fruit on maturity. The
commercial strawberry is thought to derive from an
interspecific hybrid cross between the two octaploid
species,
F. chiloensis
(L.) Duch. and
F. virginiana
Duch.
(Went 1957; Darrow 1966; Hancock 1999). Hundreds of
strawberry cultivars have been developed (Table 11.2); the
most commercially important of these is cv. Camarosa,
although it is not particularly well adapted to non-
Mediterranean European climates.
GENERAL FRUIT ANATOMY
The basic morphology of soft fruit is varied. For instance,
the raspberry and blackberry are classed as aggregate fruit
as they consist of clusters of one-seeded drupelets. The
drupelets are typically eaten as a cluster which is referred
to as the berry. The strawberry is also aggregate in structure
