A review of dipterocarps - Center for International Forestry Research

Non-Timber Forest Products from Dipterocarps
is called dammar when obtained from dipterocarps. This
is the solid or brittle resin, which results from hardening
of the exudate following evaporation of the small content
of essential oils. However, the classification of resins
is very chaotic, and in the trade the term ‘dammar’ is
also used occasionally to refer to an oleoresin.
Oleoresins
The genus Dipterocarpus is the principal source of
oleoresins. The genus has large trees with erect trunks,
the wood of which yields resin similar to copaiba. Other
genera of lesser importance are Shorea, Vatica,
Dryobalanops and Parashorea. All Dipterocarpus
species produce a high proportion of oleoresins which
come under various local names such as gurjan oil (India),
kanyin oil (Burma) and minyak keruing (western
Malesia). A well-known oleoresin comes from D.
turbinatus which is the principal source of ‘kanyin oil’
in Burma and ‘gurjan oil’ in Bangladesh and India. The
best yielding species are Dipterocarpus cornutus, D.
crinitus, D. hasseltii, D. kerrii and D. grandiflorus
(Malesia), D. turbinatus and D. tuberculatus (India,
Bangladesh, Burma), D. alatus (Bangladesh, Andamans,
Indochina) and D. grandiflorus (Philippines).
Method of Tapping
During the cold weather, a cone shaped cavity is cut into
the trunk 1m from the ground and a fire lit to char the
surface of the wound to induce the oleoresin flow. The
oleoresin is periodically removed and when the flow
stops, the wounded surface is either burnt or scraped or
a fresh wound made to induce further flow. The collection
season is November-May and a tree of 2 m girth can
yield 9 kg of resin in one season. This resin compares
favourably with balsam of copaiba (Balfour 1985).
Traditionally in Burma, oleoresin was obtained by
cutting 2-3 deep pyramidal hollows, (the apex pointing
towards the interior of the stem), near the base of the
tree and by applying fire to the upper cut surface. The oil
was collected at the bottom of the hollow which was
emptied at 3 or 4 day intervals. Fire was applied every
time the oil was removed and the upper surfaces of the
hollow were rechipped 3 or 4 times in a season. About
180 kg of oleoresin oil was collected from 20 trees in a
season. The oil was marketed locally in the form of
torches and also exported. Later, tree tapping was
prohibited owing to the heavy damage to the trees.
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In Bangladesh, the practice was to cut a deep hollow,
(transverse hole pointing downwards), in the tree and
place fired charcoal in it during the night. The oil was
removed in the morning and the charcoal replaced. The
process was repeated until the oil ceased to flow. Three,
four or more such hollows were made which often killed
the tree. In Burma the charcoal practice was not adopted.
In India, in the western-Ghat division of Coorg, the
oil was collected by cutting a hole into the centre of the
tree. It is also reported that a large notch was cut into the
trunk of the tree about 75 cm above the ground level, in
which fire was maintained until the wound was charred
and the liquid began to ooze out. A small gutter was cut
into the wood to a vessel attached to receive the oil. The
average yield from the best trees was 180 litres per
season. At 3 or 4 week intervals the old charred surface
was cut off and burnt afresh. Tapping occurred from
November to February and sick trees were rested for 1
or 2 years.
Properties and Uses of Gurjan Oil
The exudate is milky and faintly acidic and when
allowed to stand separates into 2 layers - a brown oil
which floats on the surface and a viscous, whitish grey
emulsion below. A pale yellow oil with a balsamic odour
is obtained (yield 46%) through steam distillation of the
oleoresin which leaves a dark, viscid, liquid resin.
The commercial gurjan oil is the oleoresin mixed
with small quantities of oleoresin from Dipterocarpus
alatus, D. costatus and D. macrocarpus. It is a viscid
fluid, highly florescent, transparent and dark reddish
brown in colour when seen against the light. It oxidises
when exposed to the atmosphere. The essential oil
consists of two distinct sesquiterpenes, alpha and beta
gurjunene.
The resin contains a crystallisable acid, gurjunic acid
(C H O ), devoid of acid character as in copaiba (a
22 34 4
resin containing a small portion of naphtha), which may
be removed by warming it with ammonia and 0.08%
alcohol. It is partially soluble in ether, benzol or sulphide
of carbon. The portion of resin, which is insoluble even
in absolute alcohol, is uncrystallisable. A remarkable
physical property of this oil is that at a temperature of
130oC it becomes gelatinous, and on cooling does not
recover its fluidity.
The oleoresin is applied externally to ulcers, ring
worm, and other cutaneous infections. It is a stimulant