The Production Of Sago Starch Biology Essay

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Sago starch production is an important industry in Asia-Pacific region and South East Asia (Wang et al., 1996). The production of sago starch is done through the extraction from pith tissue from the trunk of Metroxylan sagu. It belongs to the palmae family and produces large amount of starch through the extraction from stem tissue by shredding and sedimentation in water (Wina et al., 1986).

Due to this reason, the palm has important economics values and is grown commercially in Malaysia, Indonesia, Philippines and New Guinea for the production of sago starch and also for the conversion of the starch or it by-product to animal food or fuel ethanol. Metroxylon sagu is extremely important to over a million people who use the palms as their primary dietary starch source. The largest sago growing areas and the world's biggest exporter of sago are found in Sarawak, exporting about 44,700 tonnes of sago starch in 2007 to Peninsular Malaysia, Hong Kong, Taiwan, Singapore and other countries (Department of Statistics, 2007).


Metroxylan sagu is endemic to Papua New Guinea, New Britain, and the Molucca Islands (Flach, 1997). It is widely grown in Malaysia for the extraction of sago starch.

Metroxylan sagu is by far the most important economic species and is now grown commercially in Malaysia, Indonesia, Philippines and New Guinea for production of sago starch and conversion to animal food or fuel ethanol. In many countries of South East Asia, except Irian Jaya, Metroxylan sagu is mainly found in semi-cultivated stands. Irian Jaya has about 6 million ha of Metroxylan sagu. The stands of good quality Metroxylan sagu can be quite large. Papua New Guinea has an estimated 1 million ha of wild and 20,000 ha (49,400 ac) of semi-cultivated Metroxylan sagu. Metroxylan sagu is also found in Guam, Palau, Nukuoro, Kosrae, Jaluit and Marshall Islands (Fosberg et al. 1987), most likely the result of human plantation activity.

In Sarawak, sago palms are grown commercially on small-holdings. A clump density of 590 palms/acre, or 1480 palms/ha, allows an annual harvest of 125 - 140 palms/year. Since 1982, the Sarawak government had developed a plantation crop and established a specialized research station- CRAUN Research Centre (Flach, 1996). The world's first large-scale commercial plantation of 7700 ha near Mukah, was developed by the Sarawak land development agency (PELITA).

Metroxylan sagu characteristic

Metroxylan sagu is an extremely hardy plant, thriving in swampy, acidic peat soils, submerged and saline soils where few other crops survive, growing more slowly in peat soil than in mineral soil (Flach and Schuilling, 1989; Hisajima, 1994). The palm has high resistance against floods, drought, fire and strong winds.

Flowering occurs to the Metroxylan sagu at the later stage of tree cycle. It is by this stage that the starch content of the tree had reached its maximum capacity. The inflorescence is large, paniculate, and mainly terminal for most species. The palms are monoecious, having both male and female flowers on the same plant. Flowers are borne on crowded spikes, spirally in pairs (of male and hermaphrodite, functional female) flowers.

Metroxylan sagu produces fruit after flowering. When fruiting occur for Metroxylan sagu, it indicates that the tree is over-ripen and the starch content has gotten fewer. Metroxylan sagu is a monocarpic plant, after it fruits, it will wilt and die. Tradisionally, fruiting of Metroxylan sagu had been use as indicator of harvesting the tree. Fruit of Metroxylan sagu depressed-globose to obconical, 3-7 cm 1.2-2.7 cm in diameter, covered with 18 vertical rows of rhomboid greenish-yellow scales. Metroxylan sagu produces both pollinated (seeded) and parthenocarpic (non-pollinated) fruit. Seeded fruits contain a stony, white endosperm and brown testa. Parthenocarpic fruit are smaller and contain a spongy mesocarp. Metroxylan sagu fruits take about 24 months to mature.

The bark of mature palms is gray, rough, and fissured in long plates or corky ridges. The stem is frequently surrounded by deteriorating, partially attached leaf-sheaths. The lower internodes frequently have suckers and sharp to blunted adventitious roots. On younger trees the bark is smoother and paler gray to brownish in color. The inner bark is light colored and bitter.

1.3 Sago Starch Production

Sago has an exceptionally high yield level of starch. Under good conditions the yields of starch vary from at least 15 t to possibly 25 t of dry starch/ha of Metroxylon sagu at the end of an 8-year growth. Metroxylan sagu is considerably more productive for starch production compared with other palmae species (Singhal et al., 2008). As claimed by Ishizaki (1997), sago is the highest starch at 25 t/ha comparing to other top starch crop producer of the world cowith rice at 6 t/ha, corn at 5.5 t/ha, wheat at 5 t/ha and potato at 2.5 t/ha.

The cellulose fraction consisted of 89% glucose and small amounts of other sugars, such as xylose, rhamnose, arabinose, mannose, fucose and galactose, whereas xylose and glucose were found to be the major components of the isolated hemicelluloses, together with noticeable amounts of arabinose and galactose and small amounts of rhamnose, mannose, fucose and uronic acids. Lignins, on the other hand influenced the woody structural rigidity by stiffening and holding the fibers together (Sun et al., 1999).

Sago starch was obtained from extraction from the pith tissue. The pith tissue was obtained from the removal of the hard bark about 2 - 3 cm thick upon felling of the massive trunk. The farmer grated the pith using plank studded with numerous nails which shred the pith into fine granules for starch extraction. In Sarawak, fully mechanical processes are used for starch isolation by modern factories. The isolation of sago starch involves debarking, rasping, sieving, settling washing and drying. The chips obtained are further disintegrated using a hammer mill. The resulting starch slurry is then passed through a series of centrifugal sieves to separate the coarse fiber. Further purification is carried out by separation in a nozzle separator to obtain pure starches. Dewatering of the starch is achieved using a rotary drum dryer, followed by hot air drying. During the processing of sago starch three major types of by-products were produced, the bark of sago trunk, fibrous sago pith waste (commonly known as 'hampas') and wastewater (sago effluent).

1.4 Sago Waste

Sago pith waste is classified as a solid residue. A residue is a substance resulting from the processing of a product. It becomes a co-product or a by-product when profitable use is made of it. If not, the residue becomes a waste, which is defined as a material with no apparent market, social, or environmental value, which constitutes an environmental nuisance and a source of pollution.

Beside starch, small amount of non-starch polysaccharide (NSP), known as cellulose, hemicelluloses and lignin are found in sago pith waste. According to Sun et al. (1999), the cellulose fraction consisted 89% glucose and small amounts of other sugars, such as xylose, rhamnose, arabinose, mannose, fructose and galactose, whereas xylose and glucose were found to be the major components of the isolated hemicelluloses, together with noticeable amounts of arabinose and galactose and small amounts of rhamnose, mannose, fucose and uronic acids. Lignins, on the other hand influence the woody structural rigidity by stiffening and holding the fibers together.

In starch processing, fibrous by-products which contained starch residue is the main problem especially for the bigger factories, which produce them in massive quantities. Dealing with this waste is difficult, as it is not easily dried due to its high moisture and starch contents (Sriroth et al., 1999).

The amount of sago pith waste released from the sago processing factory depends mostly on the quality of the extraction process. The yield of sago starch from sago trunk is 25%-41% of the total starch content (Jalaludin et al., 1970; Horigome et al.,1991). This depends on the technique or methods that are being used by the operating mills (Cecil, 1991). The remaining starches are trapped within the parenchyma cell or the sago fiber. The sago waste usually is disposed into the river or being sold as feed for the ruminant (Mayhuddin, 1992). Sago waste has the C/N ratio of 200 (Vikineswary, 1994). The biology oxygen demand (B.O.D) of sago effluent is 3444 mg L-1. In Sarawak, 32,000 tonnes of sago waste (dry weight basis) annually (Zulpilip et al., 1991; Hassan and Hussaini, 1999) on daily basis especially in Sibu and Mukah Division, about 50-110 t of sago pith waste are produced. In general, sago pith waste contains approximately 66% starch and 14% fiber on a dry weight basis of which about 25% is made up of lignin (Chew and Shim, 1993). With the significant amount of starch left behind within the sago pith waste, it has been used as a feedstuff for ruminants in sago processing areas. The feeding value of sago pith and pith residue is close to that of sweet potato residues and as such they can be utilized more effectively by ruminants (Horigome et al., 1991). The sago pith waste may be used as animal feeding, compost for mushroom culture, for hydrolysis to confectioners' syrup and for particleboard manufacture (Phang et al., 2000).

2.0 Earthworms

Earthworms are amongst the most ancient of terrestrial animals, their ancestors possibly emerging in the pre-Cambrian some 650-570 million years ago (Valentine, 1980; Bouché, 1983). Segmented worms have also been identified from basal Cambrian strata in China and Siberia (Bengston and Zhao, 1997), and from the upper Ordovician and upper Silurian periods in USA and UK (Edwards and Lofty, 1977). Fossil embryos and cocoons were found in Recent and Mesozoic layers (Schwert, 1979; Piearce et al., 1990; Manum and Bose, 1991). Today earthworms are ubiquitous in all but the driest of regions and the present-day world distribution of the 18 families has been explained in terms of Wegener's hypothesis of continental drift (Lee, 1985; Sims, 1980).

2.1 Morphology

The basic morphology of an earthworm consists of the digestive system, reproductive system, the muscular body and a tube (Blackmore, 2002). The body wall consists of a diaphanous yet resilient cuticle, an epidermis, muscular layers, and a peritoneal lining. The space between these two tubes is the body cavity, the coelom, compartmentalized and filled with fluid that acts as a hydrostatic skeleton. Free floating cells within the coelom perform various functions and are called coelomocytes. The body is annular, formed of segments (technically called somites or metameres) that are most specialized in the anterior, divided internally by the septa (singular, septum) that correspond to the external furrows. Intestinal segments are iterations without much modification towards the tail. Due to the earthworm's subterranean habitat and its need to build and maintain burrows, there are rarely external appendages and only subtle variations in superficial form prevail. Eye spots and jaws are absent. Apart from their variations in size, body shape, and position of external pores and markings, most worms look alike. In order to identify them, it is therefore essential in most cases to perform some degree of dissection of specimens so that the nature of their internal organization can be revealed. However, earthworms can also be identified using the dichotomous key - colour, size, length and habitat.

Earthworms are promiscuous, polygamous, hermaphrodites (i.e., with both male and female organs). Their reproductive strategy involves mate location and recognition, mutual exchange of sperm, and the shedding of eggs within a protective and/or nutritive cocoon formed at the clitellum.

Peregrines are often characterized by sizes as small as 10 or 20 mm length and about one mm width in adults, e.g. Drawida sp., Microscolex sp., Ocnerodrilus occidentalis and Dichogaster sp., and the cocoons such species are proportionately small which probably facilitates their dispersal (Blackmore, 2002). Several endemic litter dwelling or arboreal species are also in the range 10-20 mm in length and about 1-2 mm diameter (Lee, 1981). For example, Metapheretima agathis and M. buckerfieldi both by Lee (1981) from Vanuatu, measure less than 17 mm.

Earthworms are found all over the world. Earthworm feedings depends on the places it is found. Earthworms from soil consist of high organic matter will consume more organic matter. Earthworms from mineral soil would prefer to feeds on the mineral substances. Earthworms found in pasture usually feeds on microflora, where else earthworm such as Eisenia fetida would prefer to consume manure.

Field populations of some species may have only a seasonal life-expectancy, remaining in embryonic dormancy in cocoons during unfavourable conditions such as drought. A maximum life span reported for Eisenia fetida was 5 years, however laboratory cultures of Aporrectodea longa survived 5-10 years (Gates, 1972), and adult Lumbricus terrestris have been maintained for an incredible 30 years (Sims and Gerard, 1985). Some 'giant' species may take years to mature and breed only every two or three years e.g. Megascolides australis as reported by van Praagh (1992).

2.2 Earthworm for vermicomposting

There are three categories of earthworms. There are epigeic, endogeic and anegeic earthworms. From these three, epigeic form of earthworms is the best for vermicomposting (Ismail, 1993). Epigeic earthworms are surface earthworms. They usually reside under the top soil and consume the organic matter found at between the top soil and the surface soil. Example of such epigeic earthworm are Eisenia foetida. Epigeic earthworms is the most efficient earthworm for vermicomposting because this type earthworm is voracious feeder on organic waste, utilize only small amount of the food for their body synthesis whereas excreting larger part of the consumed waste in digested form (Ghosh et al., 1999).

The most common types of earthworms used for vermicomposting are tiger worms (Eisenia foetida) and redworms or red wigglers (Lumbricus rubellus). Often found in aged manure piles, they generally have alternating red and buff-colored stripes. They are not to be confused with the common garden or field earthworm (Allolobophora caliginosa and other species). Although the garden earthworm occasionally feeds on the bottom of a compost pile, they prefer ordinary soil. An acre of land can have as many as 500,000 earthworms, which can recycle as much as 5 tons of soil or more per year. Redworms and tiger worms, however, prefer the compost or manure environment. Passing through the gut of the earthworm, recycled organic wastes are excreted as castings, or worm manure, an organic material rich in nutrients that looks like fine-textured soil.

3.0 Vermicompost

In nature, earthworm cast consist of excreted masses of soil, mixed with residues of comminuted and digested plant residues. Cast obtained by vermiculture are usually called vermicompost. Vermicompost is a product rich in organic bioremediated matter that differs from the compost obtained, from the same matrix for its level of humification and the greater presence of microbial metabolites. These metabolites, i.e., growth regulators and polysaccharides are responsible for the fertilizing value of casts. Vermicompost which is produced from the activity of the earthworms is rich in essential plant nutrient compare to ordinary compost. Vermicompost contains major and minor nutrients in plant-available forms: enzymes, vitamins and plant growth hormones like gibberlins and immobilized microflora. Average nutrient contents of vermicompost are much higher than mostly used farmyard manure. The quantity of inorganic fertilizer can be reduced to half if vermicomposrt is used as organic manure instead of using the farmyard manure. Vermicompost can makes the soil more fertile and improve the soil health for sustainable agriculture. Vermicompost is readily used without fear of causing burning to the plant (Tripathi et al., 2001).

Vermicomposting had been practiced in garden scale and also in industry scale. This technology had been used with varied degrees of success to treat municipal solid waste (Donovan et al., 1981), municipal sludge (Pincince et al., 1993) and kitchen waste (Appelhof, 1993). However, no study had been conducted to observe the effect of vermicomposting on sago waste.

3.1 Vermicomposting

Vermicomposting is a mesophilic process that is driven by the activity of earthworms and with help of microorganism found inside the feedstock. It consists of feeding organic materials to earthworms. Vermicomposting does not require the processed waste to reach elevated temperatures, which would actually be detrimental to earthworms.

Earthworms have an optimal pH range of 7-8 (Ndegwa and Thompson, 2000) and they suffer toxicity at high salinity levels (Romero et al., 2001), therefore ammonia-rich material such as poultry manure may need to be buffered with other materials. The threshold ammonia level for waste to be processed by earthworms is 0.5 mg/g waste on a wet basis, and 0.5% salt (Fieldson, 1988). Increased aeration accelerates the rate of waste processing by earthworms. Earthworms also have an ideal stocking density of 150 earthworms / liter in the case of Eisenia foetida (Frederickson and Howell, 2004) at which the rate of waste processing in maximized. The latter is the most efficient at consuming feed and the most commonly used species in commercial vermicomposting. Earthworms can ingest 75% of their weight daily (Ndegwa, 1999). The optimal moisture content in their feed is 75% (Ndegwa and Thompson, 2000).

Moisture content is very important for the survival and growth of the earthworms since they have poor developed mechanism for the sonservation of water. Their respiration relies on the absorption of oxygen through moist surface tissue (Lee, 1985). Tests done using municipal sludges showed maximum growth at 50-80% moisture content (Kaplan et al., 1980).

Earthworms migrate towards fresh feed, so in windrows and bins, 1 foot thick feed layers are added one at a time to draw earthworms away from the lower processed material, which is then collected. Thin feed layer additions prevent fermentation and the resulting heat buildup which is lethal to earthworms.

3.2 Feedstock for vermicomposting

Quality of vermicompost depends a lot from the raw material or the feedstock used for the vermicomposting process. Feedstock for vermicomposting depends heavily on the species of earthworms used. Different earthworm had different food preference. Earthworms found in pasture usually feeds on microflora, where else vermicomposting earthworm such as Eisenia fetida and Lumbricus rubbelus would prefer to consume animal manure.

3.2.1 Animal Manure

Animal manure are very abundant in India especially cow manure. Total annual waste biomass production from agriculture is 2500 million tonnes (Dash and Senapati, 1986). Out of these animal manure constitute 60% of the total value. Therefore cow manure is the more popular manure used in vermicomposting in India. On daily basis cow produces 11.5 kg of manure (Livestock Census Report, 2003).

Goat manure is one of the finest composting materials. It contains large amount of nitrogen and beneficial microbes. Other than goat manure other animal manure are also used as composting material, example of these manure are from cow, horse, elephant, bats and other herbivorous animal. Manure from carnivore should be avoided as it contains pathogen that can be harmful to the earthworms. Examples of the manure of such kinds are from cats and dogs (Kale, 1993).

Raw manure is not suitable for vermicomposting process because it has very high nitrogen content. The nitrogen will be released as ammonia in which if high amount is released will be fatal for the earthworms. Besides that raw manure will produced too much heat. The heat will also kill the earthworms as they prefer room temperature (Blackmore, 2002).

Animal manure for the purpose of vermicomposting process initially must be left to compost in its own heap. Then the manure should be air dried and grinded into finest floury substances. The reason is to make it easier for the earthworm to consume the manure and also to make the manure easier to mix with other substances (Kale, 1993). Manure if not used for vermicomposting process is also easy to handle. Goat manure in its natural state is already dry and usually found in pelleted form compare to cow manure. Goat manure can serve as soil addictive and mulch on its own.

3.2.2 Agriculture Waste used in Vermicomposting

Production of vermicompost depends mainly on the animal manure. Introduction of other agricultural waste is possible because the earthworm will mixed the mixture of the animal manure with the agriculture waste.

One of the popular agricultural waste in vermicomposting is the mushroom spent compost. Mushroom production is the biggest solid-state fermentation industry in the world (Moore and Chiu 2001). Correspondingly, from the production of 1 kg of mushroom, 5 kg of spent mushroom compost will be generated (Semple et al., 2001).

The vermicomposts obtained from the vermicomposting of mushroom spent waste and cow manure were rich in total nitrogen, phosphorus, and other essential elements for plants' growth and had good physical properties, low conductivity, low C:N ratios, optimal stability, and maturity. These characteristics make vermicomposts useful as soil conditioners, healthy organic fertilizers, and good substitutes in potting media (Tajbakhsh et al., 2008).

3.3 Chemical Content of Vermicompost

Chemical content of vermicompost depends a lot from the raw material for the vermicomposting process. It cannot be expected to obtain high quality vermicompost product from low quality raw material (Albanel et al., 1988). Vermicompost has higher value of available nutrient comparing to the feedstock due to the chemical changes worked by earthworms and microorganism in the media (Buchanan et al., 1988).

Determination of organic carbon content in compost is important, particularly for calculating the C/N ratio of the material. The C/N ratio is also an indication of the degree of humification of the organic materials. Total organic carbon of vermicompost is lower compare to initial substrate. Decrease in the organic carbon content of the initial substrate is due to the loss of carbon as carbon dioxide. Earthworms promote such microclimatic conditions in the vermireactor that increase the loss of organic carbon from substrate through microbial respiration (Suther, 2006).

Nitrogen content in vermicompost is dependent on the initial nitrogen present in the feedstock and the degree of composition (Crawford, 1983). Losses in organic carbon might be responsible in nitrogen addition. Addition of nitrogen in the form of mucus, nitrogen excretory substances, growth stimulating hormones and enzymes from earthworms contributed to increase of the nitrogen content (Viel at el., 1987). The C/N ratio is used as an index for maturity of organic waste.

The total phosphate in vermicompost is higher compare to the initial substrate. The increase in total phosphorus is due to mineralization of phosphorus as a result of bacterial and fecal phosphate activity of earthworm (Edward and Lofty, 1972).

The total potassium content in vermicompost is different from according to their initial origin. The reason is due to differences in the chemical characteristic of the initial substrate. Total content in sewage sludge vermicompost is higher compare to initial substrate (Delgado et al., 1995). Whereas total potassium content in coffee pulpwaste is lower after vermicompost. The total potassium in goat manure based vermicompost is lower than the initial substrate (Garg and Yadav, 2006).

3.4 Microbial Content of Vermicompost

Vermicompost are rich in ammonia and partially digested organic matter and provide good substrate for the growth of the microorganisms (Edwards and Bohlen, 1996). The suitability of vermicompost is attributed by the increased amounts of fungal hyphae. The passage of organic waste through the guts of earthworms leads to the acceleration of the humification process by the gut microflora and establishment of microflora on their egesta. Vermicompost can be effectively utilized as a carrier medium for Azospirrilum, Rhizobium and phosphate solubilizers (Sharma 2001).

Enterobacteria including Salmonella are not isolated from the gastrointestinal tract of earthworms, even when worms are raised in heavily contaminated environments (Finola et al., 1995). These data would suggest that many Gram negative bacteria, such as those responsible for many of the foodborne diseases, do not survive passage through the gastrointestinal tract of the earthworm. Since high temperatures are not part of organic matter processing by earthworms, casts may inherently contain the microorganisms necessary for disease suppression. Only a few studies have tested for disease suppression in the presence of earthworm casts (Szczech et al., 1993). Szczech and Smolinska (2001) showed a suppression of the plant pathogen Phytophthora spp. by earthworm casts.

Besides that, pathogenic bacteria includes Salmonella and E. coli are also destroyed during vermicomposting process due to competition from active microflora. Most of the human pathogens are anaerobic and cannot survive in the highly aerobic microenvironment created by earthworms during vermicomposting process.


4.0 Standard of vermicompost characteristic

Cuba is one of the leading countries in production of vermicompost. The production of vermicompost in Cuba is based on the local production of cow manure. The cow manure had been used for soil amendment. The cows are used to replace the function of tractor on the field. Vermicompost had been used on tobacco and improve the production by 31 % and enhance the quality by reducing the leaf chlorine content from 1 % to 0.4 % .




1.5 % - 2.2 %


1.8 % - 2.2 %


1.0 % - 1.5 %


4.6 % - 4.8 %


0.3 %


0.5 ppm


150 - 170 ppm


500 - 510 ppm


13.1 % - 17.3 %

Organic matter

65 %- 70 %

C/N ratio

10 - 11

(Werner and Cuevas, 1996)

4.0 Economics of vermicomposting

There are environmental benefits to processing organic waste into an environmentally friendly byproduct and to averting/reducing environmental costs (such as avoiding fines due to ground water pollution caused by organic waste disposal).

Waste can be processed through earthworms and sold at high profit depending on the effectiveness of the vermicomposting operation. Small-scale systems for vermicomposting are less capital intensive and can offer more economic flexibility, as more of these systems can be incrementally added as an operation grows. Earthworms produced in such operations can also be sold as bait or worm meal (protein source), however most of the revenue is expected to be from vermicompost since the earthworm market is limited (Fieldson, 1988).

4.1 Usage of Vermicompost in Agriculture

Vermicompost had been used as a source of organic manure in supplementing chemical fertilizer. Vermicompost had been repoted to be homogenous and fertile material suitable for plant growth (Forgaste and Babb, 1972).

Vermicompost is also an excellent source of nutrient for rice (Edwards, 1998). Summer paddy (IR- 20), with the application of vermicompost shown increased of vegetative growth on shoot roots, weight and shoots length and had better performance compared to chemical fertilizer. In low land rice, application of vermicompost increased the yield by improving the nutrient uptake, increased level of N, P and microbial load and higher level of symbiotic association of microbes in the between rice and microbes (Kale et al., 1992). When applied directly to sown rice, the seedlings turned dark green immediately after emergence (Gunathilagaraj, 1994).

Vermicompost doubled the production of wheat when the dosage of the vermicompost is 20 % of the soil used (Nijmzvan, 1952). Application of vermicompost on wheat increased the total grain yield and total dry matter production in comparison to organic manure and chemical fertilizer (Nainawatt, 1997).

Tomato had been used widely with vermicompost. Tomato yield were consistently produced greater yield compare to inorganic fertilizer. Vermicompost had also been used to suppressed the fusarium wilt (Szczech, 1999).

Vermicompost also showed positive effect when applied to vegetables. There are increased in the shoots weight, leaf areas and pepper yield in comparison with inorganic fertilizer (Hangarge et al., 2002). The improvement in plant growth and increased in fruit yield is due to the vermicompost nutrient and large increases of soil microbial biomass in the growing media. The increased of soil microbial led to production of hormones or humates in the soil acting as the plant growth regulators independent of nutrient supply (Norman et al., 2003).