A review of dipterocarps - Center for International Forestry Research

Non-Timber Forest Products from Dipterocarps
Shorea robusta or sal is another important producer
of oleoresin in Bangladesh, India and Nepal. It yields an
oleoresin known as sal dammar, ‘ral’ or lal dhuma’. Earlier
tapping methods gave low and erratic yields. The method
recently employed is to cut 3-5 narrow strips of bark
90-120 cm above the ground. When the tree is blazed
the oleoresin oozes out as a whitish liquid and on exposure
it hardens quickly and turns brown. The cut is freshened
by scraping off the hardened resin. In about 12 days the
grooves are filled with resin. The grooves are freshened
and resin is collected periodically in July, October and
January. A good mature tree yields about 5 kg of resin
annually.
The essential oil, sal resin, on dry distillation yields
an essential oil, known as ‘chua oil’. The yield of the oil
varies from 41 to 68% depending upon the source of the
oleoresin samples. The oil is light brownish yellow in
colour and has an agreeable incense-like odour, with
specific gravity 0.9420, acid value 4.42, saponification
value 15.72 and saponification value after acetylation
39.49. It consists of 96.0% neutral, 3% and 1% phenolic
and acidic fractions, respectively. Chua oil is used as a
fixative in heavy perfumes, for flavouring chewing and
smoking tobacco and in medicine as an antiseptic for
skin diseases and ear troubles. The non-phenolic portion
of the oil has a suppressing effect on the central nervous
system, the phenolic portion is less effective.
Vateria indica is also an important source of
oleoresin in India. The trade names used for the oleoresin
are piney resin, white dammar, Indian copal and dhupa.
The trees are tapped either using semi-circular incisions
or a fire is lit at the base of the tree so as to scorch the
bark, which then splits and the resin exudes. The resin is
in three forms: i) compact piney resin which is hard, in
lumps of varying shapes, bright orange to dull yellow in
colour, with a glossy fracture and resembling amber in
appearance, is called Indian dammar; ii) cellular soft
piney resin which occurs in shining masses, having
balsamic odour, and light green to yellow or white in
colour, is called a piney varnish; and iii) dark coloured
piney resin from old trees. The resin is a complex
mixture of several triterpene hydrocarbons, ketones,
alcohols and acids along with small amounts of
sesquiterprenes. On distillation, the oleoresin gives an
essential oil (76%) with a balsamic odour. The oil
consists of phenolic constituents and azulenes, with the
latter predominating. The essential oil has a marked
antibacterial property against gram negative and gram
190
positive microorganisms (Howes 1949, Chopra et al.
1958). The resin readily dissolves in turpentine,
camphorated alcohol and is used in the manufacture of
varnishes, paints and anatomical preparations. The
liquefied resin mixed with hot drying oil makes a varnish,
superior to copal, for carriages and furniture. The resin
is used to make incense, for setting gold ornaments,
caulking boats (Trotter 1940) and in rural areas, resin
mixed with coconut oil is used as torches and candles. It
is a good substitute for Malayan dammar and, in solution
in chloroform, for amber in photographers’ varnish. The
resin has medicinal value. It is credited with tonic,
carminative and expectorant properties and is used for
throat troubles, chronic bronchitis, piles, diarrhoea,
rheumatism, tubercular glands, boils etc. Mixed with
gingili (sesame) oil, it is used for gonorrhoea and mixed
with pounded fruits, obtained from Piper longum (longpepper),
and butter or ghee it is useful for the treatment
of syphilis and ulcers. An ointment of resin, wax and the
fat of Garcinia indica is effective against carbuncles. It
forms a good emollient for plasters and ointment bases
(Kirtikar and Basu 1935, Chopra et al. 1958, WOI
1989a).
In Southeast Asia the important oleoresin trees are
Dipterocarpus cornutus, D. crinitus, D. hasseltii, D.
kerrii and D. grandiflorus. The old method of tapping
is by notching a hole in the trunk and blazing to stimulate
further oleoresin flow. This is repeated at about weekly
intervals and the yield per tree is 150 to 280 ml per
tapping (Gianno 1986). A less brutal method has been
developed, known as the barkchipped method
accompanied by application of chemical stimulants,
which is less destructive and the yield and oleoresin
quality better (Ibrahim et al. 1990). The oleoresin is
processed to separate the essential oil from the resin.
The essential oil, known commercially as gurjan balsam,
is used as a fixative or a base in perfume preparations
and occasionally as an adulterant of patchouli and copaiba
balsam oils. Traditionally the oleoresin is used for
caulking the inside of boats, coating wood as a protection
against weather, in torches, and for medicinal purposes.
The oil is also used to make varnishes in backyard
industries (Burkill 1935). While the biggest suppliers
of gurjan balsam oil are Indonesia, Malaysia and Thailand,
limited quantities are produced in India and the
Philippines. Sumatra is the biggest producer of all, and
in 1984 it produced about 20 tonnes of the oil (Lawrence
1985). The oil is now becoming scarce with an