The genus Cinnamomum

166 Nguyen Kim Dao
Cassia Oil Production
The cassia oil of commerce is distilled from the leaves and twigs of C. cassia. Cassia
oil is produced mainly in China, where hydrodistillation is employed for oil
production. Cassia oil was earlier produced as a primitive cottage industry, but
now modern factories owned by communes have been established in many cassia
growing regions.
The distillation material consists of partially dried leaves and branchlets from the
shoots used for bark production. Depending upon the proportion of leaf and stem
(twigs) the quality of the oil produced may vary. Usually 3/4 leaves and 1/4 twigs are
used. The best quality oil is obtained from material harvested in the summer and
autumn from trees that are five to seven years old (Purseglove et al., 1981).
The local stills used are the directly fired type, consisting of a shallow boiling pan
made of cast iron. The rest of the body is usually made of tin or iron sheets, on which
sits the still head surmounted by a condenser in the form of a shallow pan into which
water flows. The still can accommodate about 60 kg leaf and twigs and 150 l of water.
The still is heated, often by using debarked cassia wood. The distillation process goes on
for about three to four hours. Steam and oil vapours passing through holes in the still
head are liquified at the bottom of the cooling vessel (over which there is a shallow pan
through which water flows). The condensed water and oil drip from the bottom of the
still head into the lower part of the still head, from where the oil and water mixture flows
through a pipe into an oil tank. In the oil tank, the oil and water separate. The oil is
heavier than water and collects at the bottom of the oil tank from where it is periodically
removed. The supernatent water which is milky because of suspended oil is sent
back to the still. The yield of oil by this procedure is about 0.31 to 0.33%, but could be
much higher by using more efficient equipments. The factories owned by the communes
use larger coal-fired stills which are more efficient and which yield more oil.
The leaves yield more oil than twigs (0.54% versus 0.2%). The highest oil yield is from
vigorous, five to seven year old trees. The quality of the oil depends upon the leaf material
used and varies according to season. In winter and early spring the oil quality is said
to be inferior to that from leaves harvested in mid-summer and autumn (Guenther, 1950).
Economic Value
Cassia has great economic value both in Vietnam and China. Long ago Hai Thuong Lan
Ong appreciated it as one of the four tonic medicinal sources, (Ginzeng, Budding antler,
Cassia cinnamon, Aconite). The cassia tree is commonly grown in mountainous forest
regions of Vietnam, however, the trees grown in Tra Mi district (Quang Nam province)
and Tra Bong district (Quang Ngai province) have been valued as the best quality cassia.
The Chinese call Tra Mi cassia cinnamon “Cao Son Ngoc Que” (gem cinnamon of high
mountain). With long-standing experience, people in the Tra Mi and Tra Bong districts
have made cassia growing their main profession. Nowadays income from cassia growing
accounts for 60% of the total income of the people in these districts. Economically,
income from the cassia cinnamon business has long-term and short-term advantages, and
it takes the main role in socio-economic development of ethnic people in high mountainous
regions of Vietnam. Cassia growing is important as a means of reforestation, for
transforming poor, desolate and waste forest into a growers’ forest ensures the ecological
and environmental balance of the whole region. The depleting forestry resources in the