Agriculture Reference
In-Depth Information
losses are estimated at 25-50% in developing countries (Kader, 1992). Until
recently, little has been known about the effect of postharvest physiology of
fruits and shelf life. There is a need to develop appropriate techniques for fruit
handling, preservation and processing to maximize returns from fresh and
processed fruit products. The development of such postharvest systems requires
understanding of current practices and how they influence postharvest losses.
In a study undertaken in Zimbabwe (Kadzere
et al.,
2004), the authors
interviewed 180 producers (collectors), 120 processors and 210 marketers. The
results indicated that community dwellers had knowledge of the ripening
period. The time of the year, colour changes, skin softness and abscission were
the indicators used by the respondents to determine ripening, depending on
species. Fruit ripening overlapped for many species, opening an avenue for
having fresh fruits throughout the year (Akinnifesi
et al.
, 2004a). For
Adansonia
digitata
, about 85% of users or harvesters climbed the tree to harvest because
the fruit did not readily abscise when ripe (Kadzere
et al.
, 2001). Most of the
harvesters collected fruits that dropped naturally, e.g. for
Parinari curatellifolia
(99%),
Sclerocarya birrea
(95%),
Uapaca kirkiana
(78%),
Ziziphus mauritiana
(61%) and
Strychnos cocculoides
(69%). Other means of harvesting included
shaking the tree or throwing objects at the tree crown, hitting the stem to
dislodge the fruits. Most
Uapaca kirkiana
trees had big scars and wounds on the
stem because of these inappropriate harvesting methods. Fruits were broken
and branches severely damaged in many cases. Fruits were harvested when
unripe, just ripe or well-ripened, and were harvested several times during the
season (Kadzere
et al.
, 2006a, b, c). However, allowing the fruits to drop often
results in contamination and attacks from pests and diseases.
More than half of the fruits harvested were often retained for home
consumption for
Adansonia digitata
(59%),
Azanza garckeana
(73%) and
Strychnos cocculoides
(76%), but less frequently for
Uapaca kirkiana
and
Ziziphus mauritiana
(28-33%), indicating that these were the most frequently
sold fruits.
Uapaca kirkiana
and
Z. mauritiana
were sold by 84% of fruit
marketers. Before marketing, several methods were used to add value -
cleaning, grading, packaging, protecting from the sun - but these varied with
species. Grading was done for most fruits before marketing (80% for
Uapaca
kirkiana
), mainly based on fruit size, as bigger fruits fetch better prices. For
instance, no preservation method was observed in Zimbabwe for
Uapaca
kirkiana
,
Strychnos cocculoides
and
Sclerocarya birrea
, whereas 54-86% of
respondents preserved
Ziziphus mauritiana
. Thirty-one per cent of respondents
shaded
Uapaca kirkiana
from direct sunlight.
Ziziphus mauritiana
and
Parinari
curatellifolia
were sun-dried as whole fruits before storage, or fermented as
solid to extend shelf life and make fruit available during the off-season (Kadzere
et al.
, 2001).
Strychnos cocculoides
was rehydrated before consumption.
Controlled dehydration has been reported to enhance palatability and boiling,
which may sometimes lead to loss of vitamins (Kordylas, 1991). Marketers
often performed grading, cleaning, packaging for most fruits as well.
Postharvest deterioration often results from cracks during harvesting,
mechanical damage during transportation and storage, and insect pest damage
(Kadzere
et al.
, 2001, 2006b). Most marketers (78-84%) indicated that
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