Agriculture Reference
In-Depth Information
12
Kiwifruit, Guava, Passion Fruit
and Lychee
Graham Farrell
The account presented here concentrates on recent findings
and new initiatives in the post-harvest aspects of four
commodities with important roles in an expanding market
for exotic fruits and vegetables. General, comprehensive
volumes on the post-harvest behaviour and handling of
these fruits,
inter alia
, are given by Nagy and Shaw (1980),
Morton (1987), Mitra (1997), Wills
et al
. (1998), Thompson
(2003) and Gross
et al
. (2002). Warrington and Weston
(1990) provide an in-depth study of all aspects of kiwifruit
from a New Zealand perspective.
major producer in the United States, accounting for 95% of
all kiwifruit produced nationally. Chinese production is
forecast to increase rapidly, reaching about 0.5 million tons
(MT) and accounting for half of world output by the end
of 2006 (Huang
et al
. 2004). Table 12.1 shows some
production figures by region.
Harvesting
Kiwifruit are nonclimacteric and are among the few
fruits that retain large amounts of starch at maturity.
Hydrolysis of starch continues after harvest even at low
temperatures and is complete a few weeks later, when the
starch is converted to soluble sugars (mainly glucose and
fructose, with some sucrose). At the limit of carbohydrate
accumulation kiwifruit will have reached the best quality
for consumption and so delays in harvest will not further
improve the flavour (Strik 2000).
In the past, maturity was based on arbitrary harvest
dates, fruit colour or firmness but these characters are not
good guides to maturity. However, firmness is used in the
United States, with a minimum force of 6.4 kg, using a
penetrometer with an 8 mm tip, considered appropriate,
together with a minimum soluble solids content (SSC) of
6.5% (Crisosto
et al
. 1999). Penetrometer readings
should be taken on fruit at 37-39°C (Crisosto 1997). In
New Zealand, measurement of firmness using a noncontact
laser air-puff method has been described by McGlone and
Jordon (2000).
Positive correlations between SSC and fruit maturity and
eating quality have been established, and so refractometer
KIWIFRUIT
The genus
Actinidia
comprises about 50 species of
kiwifruit, mostly from temperate forests in south-western
China. The main commercial variety is Hayward (
Actinidia
deliciosa
(A. Chev.) C. F. Liang & A.R. Ferg.), preferred
for its good storage characteristics over other varieties, but
A. chinensis
Planch. and the hardy kiwifruit
A. arguta
(Sieb. & Zucc.) Planch. ex Miq. are also cultivated com-
mercially. Kiwifruit has been an economic success mainly
because of its good keeping qualities over long periods at
0°C (Hewett
et al
. 1999). Mature fruits are broadly oval,
green-brown in colour and densely covered with fine hairs.
The pulp is bright green with a mass of small black seeds.
Kiwifruit plants are vines with the fruits borne on long
pedicels (Cheah & Irving 1997).
Production
Italy is the main producer of kiwifruit, followed by
New Zealand and Chile (Rushing 2002). California is the
