Sago Palm Cultivation Environmental Benefits

By Henrylito D. Tacio

Davao City, 1 March 2010. If only Filipinos are aware of its multifarious uses, the unexploited sago (scientific name: Metroxylon sagu) has the potential to uplift economic and social conditions in the countryside, especially in the Visayas and Mindanao regions. Technologies to enhance the cultivation of the plant can lead to the development of the sago industry.

But more importantly, sago can help curb the food shortage in rural areas.  In comparison with other starch crops in the Philippines like rice, corn, wheat, and potato, the productivity of sago per land area is the highest, according to a study done by Prof. Alan B. Loreto of the Philippine Root Crop Research and Training Center.

Scientists considered sago as the world’s biggest producer of starch.  Loreto’s study showed sago palm to be more productive than rice, producing four times more starch (100-200 kilograms per palm), which is enough to feed a family with 4-5 members for a month.  It is also the least labor-intensive starch to harvest and takes 10 days only for a person to process.

The sago palm has enormous starch deposit in its trunk.  The starch is made through the following process: The sago palm is felled (this is done just before flowering).  The trunk is split lengthwise and the pith is removed.  The pith is crushed and kneaded to release the starch.  The pith is washed and strained to extract the starch from the fibrous residue. The raw starch suspension is collected in a settling container.  

The sago starch can be stored for weeks or months, although it is generally eaten soon after it is processed.  In Southeast Asia, sago starch is used as a staple food.  Before rice came into existence, sago was the main source of carbohydrates of people in Indonesia, where it was known as the “staff of life.”

In Papua New Guinea, where sago palm is the most dominant plant in the area, sago is considered a major staple food.  Locally called saksak, it is traditionally cooked and eaten in various forms, such as rolled into balls, mixed with boiling water to form a paste, or as a pancake.

In the Philippines, sago has a stigma attached to it.   Only the natives in the hinterlands and tropical rainforests, who do not cultivate lands for either rice or corn, eat sago as their staple.  In the past, however, the people in Mindanao use sago as staple food.  During the war, Cebuanos also reportedly ate sago. 

Nutrition experts say one hundred grams of dry sago yields 355 calories, including an average of 94 grams of carbohydrate, 0.2 grams of protein, 0.5 grams of dietary fiber, 10 milligrams of calcium, 1.2 milligrams of iron, and negligible amounts of fat, carotene, thiamine, and ascorbic acid. 

There are more uses of sago starch than just food.  “In the food industry, native starches have a very limited use, such as food ingredient or as edible films and food packaging, but recent technologies have expanded the use of starch by developing them into ‘modified starches’ with more stability and gel strength,” says Dulce M. Flores, a professor of food science at the University of the Philippines-Mindanao.

In recent years, sago starch has been modified chemically and used as absorbent starch gels.  These are used in such products as ice packs (to keep materials colder for longer period of time), fragrance gels (as they reduce evaporation), bait and gaming gels (they hold scent and soluble baits in traps), binder (for foundry core, charcoal, and briquettes), and absorbent for removal of excess water in athletic fields and construction sites.

Sago starch can also be used as raw material for conversion to products like glucose, high fructose glucose syrup, and monosodium glutamate for the food and beverage industry.  It can also be converted into maltodextrins and cyclodextrins, which are widely used as carrier for spices, flavors and seasoning, and as dispersants for instant dry mixes.  Both also function as processing aids for foods and the pharmaceutical industry for modifying taste, texture, color, and flavor.

Sago starch is not just limited to its uses for the food industry, but can also be used as a key material input in various industries such as paper, plywood, and textile industry. Sago starch is also used to make adhesives and paper.

Sago starch can converted further through fermentation to be used for producing biodegradable plastic and ethanol (gasohol). Its residual biomass can similarly be used as a feedstock for the production of power and heat.

The starch is also used to treat fiber, making it easier to machine. This process is called sizing and helps to bind the fiber, give it a predictable slip for running on metal, standardize the level of hydration of the fiber, and give the textile more body. Most cloth and clothing has been sized; this leaves a residue which is removed in the first wash.

In addition to its use as a food source, the leaves and trunks of the sago palm are used for construction materials and for thatching roofs. The leaflet midribs and the outer parts of the leaf petiole, on the other hand, are used for weaving mats and baskets.

In Aklan, people find sago as the best source of material for making shingles used as roofing material for light houses or huts. According to Michael Ibisate, research coordinator of the Aklan State University’s College of Agriculture, Forestry and Environmental Sciences, many shingle makers in the province prefer using sago leaves over nipa leaves because sago leaves are more -durable, especially when used in coastal areas. Sago shingles fetch a higher price than nipa shingles.

The sago palm is found in tropical lowland forest and freshwater swamps across Southeast Asia and New Guinea. In the Philippines, it is indigenous to Mindanao, where it grows in abundance in the marshes of Agusan and nearby provinces that are populated by the Manobo tribe.  Other sago growing areas can be found in Leyte, Cebu, and Panay.

The palm tolerates a wide variety of soils and may reach 30 meters in height.  It grows very quickly, up to 1.5 meters of vertical stem growth per year. The stems are thick and either are self-supporting or have a moderate climbing habit. The leaves are pinnate, not palmate. The palms will only reproduce once before dying; they are harvested at the age of 7 to 15 years, just before flowering.

There are several kinds of sago palm, but the common variety grows in clumps of several trunks and suckers and can be harvested on a sustained basis.  It only bears fruits when it is cross-pollinated by insects.  The fruits take about one and a half to two years to mature.

A monocot and a sucker-producing plant, sago can be propagated by suckers, or by seeds. Suckers with unopened buds are the best planting materials.   There is now a growing demand for sago palm as ornamental plant, both for use indoor and outdoor.

UP’s Prof. Flores is batting for the growing of sago palms as they possess environment-saving properties.  For one, sago palms can stabilize river banks with its dense roots, thriving even in polluted waters, and trapping silt, industrial pollutants and nutrients.  Sago palms are common in wetlands, creeks, and other areas where water is abundant.

For another, they act as excellent carbon sink for carbon sequestration, “thereby mitigating the greenhouse effect and global warming arising from the release of carbon dioxide into the atmosphere,” Prof. Flores said.