Mango - Crop Post-Harvest: Science and Technology - page 124

adopted to alleviate the adverse chilling effects. However,
the adoption of a strategy depends upon the availability of
necessary facilities and resources.

Desapping is a post-harvest operation which involves
draining of latex from the fruit so as to avoid or reduce the
incidence and severity of sapburn. Different post-harvest
techniques can be applied to avoid the damage. The
common handling practice involves harvesting fruit with a
long stem attached and transporting the fruit to the packing
shed in plastic crates (Holmes et al . 1993). The approaches
to reduce the sapburn include placing destemmed fruit on a
conveyer or rack under a water spray for 20 to 30 minutes,
destemming of fruit immersed in a calcium hydroxide
solution (1% w/v), spray or dipping in a detergent solution
(0.1%) just before destemming, applying surface coating
prior to desapping, washing with 1% aluminium potassium
sulphate, and packing with short stems (Brown et al . 1986;
Holmes et al . 1993; Ledger 1991; O'Hare 1994; O'Hare
et al . 1999; O'Hare & Prasad 1992; Shorter & Joyce 1994).
The use of manual harvesting aids reduces the incidence
and severity of sapburn in addition to saving labour costs
due to elimination of the desapping operation (Holmes
et al . 1993). Using harvest aids, mangoes are picked with
long poles or by hand without stems and dropped onto a
sloping canvas catching device soaked with a detergent
solution. The fruit are then conveyed through a detergent
dip or spray and placed into field crates and sent to the
packing shed (Holmes et al . 1993).

Skin disorders
Sapburn
Mango, being a member of Anacardiaceae family, has an
extensive resin duct system in fruit and stem; there is no
continuity between the fruit and stem ducts (Jole 1981).
When fruit is detached from the stem, the sap or latex
bursts out with a considerable pressure and smears over the
fruit surface, damaging the skin with symptoms ranging
from small dark spots to dark sunken blotches (Bagshaw &
Brown 1989; Brown et al . 1986; O'Hare 1994; O'Hare
et al . 1999). The fruit sap contains both aqueous and non-
aqueous (oil) phases (Loveys et al . 1992). The non-aqueous
phase contains terpinolene which is responsible for skin
burn while aqueous components are harmless (Loveys
et al . 1992; O'Hare et al . 1999). However, the ratio of the
aqueous phase to the non-aqueous phase varies among
cultivars. For example, among Indian mango cultivars,
'Seedling' and 'Totapuri' had non-aqueous to aqueous
ratios of about 1:2, and 'Mallika' and 'Alphonso' had
about 1:3 and 1:4, respectively, indicating the presence of
relatively large amounts of non-aqueous phase in these
cultivars. Whereas, 'Malgoa', 'Banganapalli' and 'Raspuri'
cultivars yielded very little non-aqueous phase with
ratios of 1:13, 1:11 and 1:7, respectively (Saby John et al .
1999). The extent of sap injury was regulated by several
factors including total sap flow, oil content in sap and lenticel
distribution (Loveys et al . 1992; O'Hare 1994). 'Kensington'
mangoes are highly prone to sapburn because their latex
contains very high levels of terpinolene as compared to
'Irwin' (Loveys et al . 1992). The latex levels in some Thai
mango cultivars with less sapburn susceptibility are in the
range of 0.16−0.48 ml/fruit, while it is 1.67 ml/fruit in
'Kensington' mangoes (O'Hare 1994). The mechanism of
sapburn injury involves the complex interaction among
terpenoid components of sap, polyphenol oxidase, peroxi-
dase, and polyphenols of the skin (Saby John et al . 2002,
2003). Limonene, ocimene and β-myrcene, the major
terpenoids identified in saps of Indian varieties, caused
sapburn injury. The skin of 'Totapuri' cultivar had very low
level of polyphenol oxidase, peroxidase and polyphenols
compared to other varieties and was found highly resistant
to sapburn (Saby John et al . 2002). Sapburn seriously
impairs the visual quality of fruit which leads to lower
consumer acceptance (O'Hare et al . 1999). The damage to
skin also encourages some pathogens to grow, perpetuate
and cause rotting.

Etch browning
Apart from sapburn, a number of forms of blemish have
been identified and collectively grouped under the term
'etch' which consists of numerous small brown flecks,
which when viewed from a distance give the appearance of
a brown blemish (O'Hare et al . 1999; Underhill et al .
1996). The etch symptoms are scattered all over the fruit
surface but more at contact points among fruit and towards
the stem end (O'Hare et al . 1999). The presence of etch
similar to sapburn also reduces the consumer acceptability
of fruit. A detailed study on characterization of 'etch
browning' revealed that mango sap appears to be a greater
etch inducing agent than detergents and that the problem
can be reduced by minimising the wet contact times in the
harvest and handling operations (O'Hare et al . 1999).

Internal breakdown
Internal breakdown (IB) is a common term used to describe
disorders of mango fruit mesocarp related to premature
and uneven ripening. However, it is an umbrella term
which covers many disorders such as spongy tissue, soft
nose, jelly seed and stem-end cavity. The attempts made to
clearly distinguish these disorders and use appropriate
terminologies in literature have not so far been successful.