SAGO PALM 26-2: 44−52 (2019)

Evaluation and Development of Sago Palm as a
Natural Starch Resource in the Tropics
Yoshinori Yamamoto*Former Faculty of Agriculture, Kochi University, Nankoku, Kochi 783-8502, Japan
yamayosi@kochi-u.ac.jp

Keywords: food safety and security, International Sago Research Center, potential starch yield, sago factory,
sago starch, starch demand and consumption
IntroductionMore than 40 years have passed since the FirstInternational Sago Symposium was held in Kuching

1. Characteristics of the sago palm
1) Growth environment

The sago palm (Metroxylon sagu Rottb.) is

in 1976. During this period, an international sago

indigenous to the lowlands of Southeast Asia andpalm and sago starch, as well as the social aspects of

Wasito, 1986). Sago palms can grow under a wide

symposium was convened every 2–6 years. At the
symposia, many research results related to the sago

the sago palm in the local community, have beenreported. Moreover, many research results were
submitted to various journals, and some were also

published in a book, The Sago Palm, by the Society of
Sago Palm Studies of Japan, in 2015. However, thesago industry, especially plantation development,

processing, and marketing, are lagging terribly behind
their potential (Jong, 2015).

In this paper, first, I would like to clarify to what

extent we have already studied the characteristics ofsago palm, such as growth environment and starch
productivity per individual palm and per area basis.
Second, I try to describe the characteristics of thesago palm from the viewpoints of adaptation toclimate change, agronomic traits, and food safety

and security to consider the sago palm as animportant starch crop in the Tropics in the future.
Third, I mention the starch supply and demand in

the world to clarify the role of the sago palm as astarch resource in the Tropics. Finally, I would liketo propose my ideas for the development of sago
palm research, as well as sago starch production andutilization for the future.

Melanesia, located between latitudes 10° N and 10° S,
to an altitude of 700 m (Flach, 1977; Rasyad andrange of environments, except drought. It has sometolerance to salt and flooded soil conditions. Sagopalms are growing at the seaside on Tebing Tinggi
Island, Riau, Indonesia (Yamamoto et al., 2003a), andflood-prone areas in Indonesia, Malaysia, Papua New

Guinea, etc. Sago palms can grow in various types ofsoil, including peat soil (Sato et al., 1979). It has been

said that the sago palm is the only crop that can growin deep peat soil without any management. However,Yusuf et al. (2015) recently concluded that the sago

palm cannot grow well in peat soil more than 5 m
deep even with enough fertilizer applied. This implies
the need for further detailed studies on the effects ofpeat soil on the growth and yield of sago palms in

relation to the type and deepness of peat soil. There
are few reports on sago palms growing at higher

elevations. Sasaoka (2006, 2007) reported sago palms
growing at the mountainous area, around 730 m

elevation, on Seram Island, Maluku Province,
Indonesia. The starch productivity of sago palms at
high elevations should be clarified to consider the
introduction of sago palms to these areas for foodsafety and security in the future.

Evaluation and Development of Sago Palm as a Natural Starch Resource in the Tropics

2) Starch productivity(1) Starch productivity of individual palms

The starch productivity of individual sago palms

varied greatly—almost 0 to 1000 kg dry starch—by
regions and/or folk varieties (hereafter, variety)(Yamamoto, 2015a). Wild-type sago palms growing in
the presumed area of origin showed low starch content

due to suspected less efficient processes of synthesizing
starch from sugars (Yanagidate et al., 2009). Moreover,sago palms growing in natural sago forests showed
higher water percentages in the pith (Yamamoto,2016). The starch productivity of cultivated sago palms
is mainly determined by the biomass produced until
harvesting (flower bud formation to the flowering

stage), but not by differences in the ratios of dry matter

distribution to the harvested portion (pith) or starchpercentage in the pith (Yamamoto, 2015b; Yamamoto

et al., 2016). The biomass is mainly determined by theleaf area per palm, and the differences in leaf area perpalm among the varieties are determined by thedifferences in leaf area per leaf caused by differences in

the leaflet width (Yamamoto et al., 2014; 2016). The
growth duration from trunk formation to harvestingalso affects the starch yield through the biomass
production (Yamamoto, 2011).

Starch productivity is also affected by environmental

conditions, such as soil types, underground waterlevels, sea water invasion, and elevation. Although
Yusuf et al. (2015) reported the impossibility ofcultivating sago palms as an economic crop in peat soil
more than 5 m deep, some researchers have reported
that the starch productivity of sago palms grown indeep peat soil were comparable to that of those grownin mineral soil (Sim and Ahmed, 1978; Kueh et al.,
1991; Yamamoto et al., 2003b).

Sago palms can tolerate flood water during monsoon

45

yield as compared to those growing more than 100 mfrom the sea, although the starch percentage in the pith
was comparable to that of palms growing inland(Yamamoto et al., 2003a). Sago palms growing atelevations over 730 m showed slightly thicker
diameters and slightly shorter statures, as compared tothose growing in lowlands (Sasaoka, 2006; 2007). The
starch content in the pith of sago palms growing at
higher elevation may be lower than that of thosegrowing in lowlands.

Cultivation management, such as thinning suckers,

water management, fertilizer application, weeding, etc.,
may strongly affect the growth and starch yield of sago

palms, but there are few reports related to these factors.
Under high density conditions without thinning, trunks

grew longer, but the diameter became slender(Yamamoto, 2015a), and starch percentages in the pith
were also lower in these palms. It takes a long time toclarify the effects of cultivation management on growthand starch yields, but it is essential for establishing asago plantation with sustainable and stable productionin the future. Regarding sucker management,
Nakamura et al. (2015) and Nabeya et al. (2015)

analyzed the growth patterns of sago palm suckers after
transplanting.

Regarding the starch productivity of sago palms, it isimportant to recognize the differences in starch yield bydifferent extraction methods. Chemical analysis

showed that, as compared to 100% starch extraction

efficiency when using acid such as perchloric acid,extraction efficiency was about 80% and about 50%
when using the electric blender and the traditional

extraction method, respectively (Miyazaki et al., 2006;
Schuiling, 2006; Yamamoto et al., 2007).

(2) Starch productivity of sago palm per land area

As compared to research data regarding the starchseason in Southeast Asia and Melanesia, but it cannot

yield of individual palms, there are few reports regarding

and this mechanism has been clarified by Ehara et al.

sago palms may be that sago palms grow in a scatteredform trunk under deep water throughout the year. The

sago palm tolerates sea water invasion, to some extent,(2006, 2008). Sago palms at the seaside of Tebing

Tinggi Island showed greatly inferior growth and starch

the starch productivity per land area. One reason for thelimited research on starch productivity per land area of

fashion, and it is difficult to find appropriate sites withuniform palm density. Following the quadrat method andY. Yamamoto

46

counting and measuring the length of all trees that havecombining the number of harvestable palms per ha, thethe starch yield per ha over time at a few sago palmand estimated the range of the realizable starch yield of

formed trunks, Osozawa (1990), Yamamoto et al.

(2008), and Yanagidate et al. (2009) reported changes ingardens in Luwu, South Sulawesi; Tebing Tinggi Island,

Riau; and Kendari, Southeast Sulawesi Indonesia,
respectively. According to the data obtained, the starchyield (by chemical analysis) per ha ranged from 4.5 to

13.5 tons (average: 9 tons) per year in South Sulawesi

and from 1.4 to 22.2 tons (average: 10.2 tons) per year in
Riau. The results clearly showed that if suckers were notwell controlled, it would be very difficult to achievesustainable and stable starch production, and the yield

total number, and 1/2 and 1/3 at densities of 8 m x 8 m

and 10 m x 10 m, respectively, that is 33–156 palms/ha,

sago palms as being 3.3–124.8 t/ha/year. Considering
the reduction of the harvestable number of palms when
the individual palm starch yield is increased, heestimated the potential yield to be 25–40 t/ha/year.

(3) Sago starch productivity as compared withthat of other starch crops

The starch productivity of the sago palm wascompared with that of other major cereal, root, andtuber crops (Yamamoto, 2015a) (Table 1). For the

Table 1. Comparison of starch yield of sago palm with that of major cereal, root and tuber crops.

gradually decreased with years of harvesting. Thesemajor crops, the world average yields from FAOSTAT

starch production.

starch percentage. For the sago palm, Cases A, B, andresults also clearly show the importance of managing
sago gardens or plantations for sustainable and stable

Regarding the potential starch yield, Flach (1980)

estimated about 25 t/ha/year when 50% of palms are

harvestable per year, at a planting density of 6 m x 6 m(277 palms/ha), and the average starch yield per palm

is 185 kg. On the other hand, applying the starch yielddata of individual palms obtained (100–800 kg),
Yamamoto (2006) calculated the starch yield per ha by2012 are quoted. The starch yields of these crops were

calculated by multiplying the average yield and the

C indicate reasonable starch yields per palm of 100,
200, and 300 kg, respectively. The starch yields were
calculated by multiplying the yield per palm and thenumber of harvestable palms per ha per year, 30 or 50
palms. These numbers are equivalent to one-third andhalf of the total number of clumps planted in a 10 m x
10 m square. The results suggest that the starch yield ofEvaluation and Development of Sago Palm as a Natural Starch Resource in the Tropics

47

the sago palm is considerably higher than those of

starch crops to transient heat, droughts, floods, etc., that

2. Sago palm’s tolerance of climate change and its

particularly sensitive during the flowering and ripening

major cereal, root, and tuber crops.

role in food safety and security

The agronomic characteristics of the sago palm as astarch-accumulating palm were compared with those of
cereal, root, and tuber crops (Table 2). Stems (trunks)
are utilized in starch accumulation, and the palms arepropagated by seed or sucker. Also, the input andtechniques for cultivating, harvesting, and postharvest

processing are lower and easier, as compared to thoseof cereal crops. Moreover, the storage ability of starch
after drying is as high as in cereals.

Figure 1 shows a comparison of the tolerance of

have occurred frequently with climate change in recent
years. It is presumed that in cereals, crops are

period, and in root and tuber crops, crops are
susceptible to these transient changes of themeteorological environments during the tuberous

root/tuber formation and developmental period. In

cereals, when these transient meteorologicalenvironments are encountered during the flowering

period, fertilization is unsuccessful, to various degrees;

consequently, yields are partially reduced, or there is no
harvest. Meanwhile, such an encounter at the ripeningstage results in the early termination of ripening andpoor maturity, resulting in a decreased yield. In root

Table 2. Agronomical characteristics of starch crops

Crops

Conditions*

Growth stage

Responses of crops

Results to yield

Heat

Flowering

Failure of fertilization

No yield

CerealsDrought
Grain filling

Earlier stopping/ notadequate accumulation

Yield reduction

Failure/delay of root/ tuber
formation

No yield

Development

Earlier stopping/ notadequate accumulation

Yield reduction

Trunk formation
to flowering

Temporary growth
retardance

Low influence on
growth and yield

Flooding

Root/ tuber
crops

Heat
Drought
Flooding

Heat
Sago palm

Drought

Formation

Fig 1. Comparison of tolerability of starch crops to the climate change
Flooding*Transient defective meteorological conditions due to climate change.

Y. Yamamoto48

and tuber crops, when these defective environments are

the calorie production per ha was calculated using theon the retardation and/or degree of formation of theroughly estimated minimum calorie intake per capita

encountered during the tuberous root/tuber formation
period, harvesting is lost or yield is reduced, depending
starch storage structure. An encounter during the

growth period of tuberous roots/tubers causes low

yields due to the early stoppage of starch accumulationand poor accumulation.

As compared to these cereals, roots, and tuber

crops, the sago palm’s development of the stem

(trunk), which is a starch accumulation organ, is little
influenced by these transient defective environments.
It is estimated that encounters with these defective

environments during the starch accumulation period
only result in a reduction of starch accumulation for avery short period, as compared to the length of thegrowing period (from trunk formation and flowering).
Therefore, the influence on the final starch yield issmall. In other words, the sago palm is considered tobe more tolerant of transient defective environments

due to climate change than are general annual starch
crops. Therefore, much more attention should be paid
to the sago palm from the viewpoint of food safety
and security in the Tropics.

Next, I tried to consider how many people sago palm

can support as an energy supplier as compared with rice
(Table 3). For rice, I show the world average paddy

yield from FAOSTAT 2012. The average yield (4,410

kg per ha) was converted to the milled rice yield, andcalorie per 100 g of milled rice (356 kcal) (Kagawa,

2001). The calorie production per ha was divided by the
per day (2000 kcal) (UNHCR and WFP, 1997; MAFF

2018) determined to support the population per ha perday. The value is 4,945 for rice. For sago palm, thestarch yield per ha was calculated in the same way as

mentioned above, that is, combining the starch yield perpalm for 100, 200, and 300 kg and the number of
harvestable palms per ha, 30 or 50 palms. The starchyield ranged from 3 to 15 ton per ha, and the calorie
production per ha was calculated by multiplying the

starch yield and calorie per 100 g starch (349 kcal)(Kagawa, 2001). Then, following the same method in
rice, we calculated the supporting population per ha perday. As compared to rice (world average yield), thesago palm can support more people in any case, withratios ranging from 1.06–5.29.

These characteristics and estimations of sago palmsuggest that it should be considered as a promising
candidate for a supplementary food crop (energy

supplier) in the humid tropical countries for foodsafety and security as well as a promising industrial
starch crop.

3. Role of sago starch in the starch market andproblems as a starch supplier

The world starch production in 2015 was 38.465

Table 3. Number of peoples can be supported by rice and sago palm

Evaluation and Development of Sago Palm as a Natural Starch Resource in the Tropics

49

million tons. Corn, cassava, potatoes, wheat, and60,000 tons of sago starch were produced per year inrespectively, of the total production (Agriculture andmainly used to produce vermicelli (thin pasta), biscuit,miscellaneous crops, including sago palm starch,

contributed 43.8, 22.8, 4.6, 4.3, and 1.9%,
Livestock Industries Corporation 2016b) (Table 4).

Twenty-one percent of the total starch production was
contributed by processed starch. Of these starches,

90% of cassava starch was produced in Asia,
especially in Southeast Asian countries such as

Thailand, Vietnam, and Indonesia. However, there areworries about stable cassava starch production inSoutheast Asia due to unstable meteorologicalconditions and the risk of outbreak of pests anddiseases in the near future. On the other hand, world

starch consumption is anticipated to increase at a rateof 2.5–3.5% per year in the medium term and comesto a total of 5.5 million tons from 2014 through 2019
(Agriculture and Livestock Industries Corporation,
2016a) (Table 4). Starch prices for exporting are

Malaysia, mostly in Sarawak, and about 20,000 tons

were exported to Japan, Singapore, etc. Sago starch ismaterial for saccharification, sodium glutamate,cosmetics, etc. (Agriculture and Livestock Industries

Corporation 2012). In Cirebon, Indonesia, there arearound 60 sago noodle (Sohun) factories that imported

110,000–170,000 tons of sago starch per year from
Riau (Yamamoto et al., 2010). In Japan, sago starch ismainly used as a dusting flour for noodles such asudon, ramen, and soba or dumpling skins such as
gyoza and shumai (Kondo, 2015).

As the starch characteristics of sago palm are similar

to those of cassava starch, except amylose content andretrogradation (Kainuma, 2015), stable andconsiderable amounts of starch production withimproved quality are essential if sago palm starch is toenter into the global starch market more strongly in the

Table 4. Changes in starch production and consumption of each kind of starch.

higher in the order of processed starch>potato>corn ≒future. Currently, sago starch has been mainly

supply and demand (Agriculture and Livestock

palm plantation has not completely succeeded. Because

wheat>cassava starch, and the price is greatly affectedby the material price as compared with the balance ofIndustries Corporation, 2016a).

Sago starch has been mainly produced in Malaysia

and Indonesia, but most of it was consumed in theircountries of origin, and only a small amount of sago
starch was traded internationally. For example, about

produced by small-scale factories in Indonesia andMalaysia, and a large-scale sago factory with a sagoof this situation, the quality of sago starch is still
variable, as compared with other natural starches.

Regarding the starch productivity of the sago palm,

natural sago forests in Papua and West Papua States inIndonesia and in Papua New Guinea may have high50

Y. Yamamoto

potential, but the development of forests to use ingeographical locations, history of sago palm cultivationof sago starch with acceptable quality is the only way

as the most appropriate place for the establishment ofstarch production has just started in West Papua State,
Indonesia. A constant supply of considerable amounts

to gain a place in the global starch market. At the sametime, it is essentially necessary to produce sago starch
at a price comparable to or lower than that of cassava
starch to be able to compete with it as well as withother natural starches.

4. What can we do to develop sago palm as a natural
starch resource in the Tropics?

Jong (2015) reviewed changes in sago starchand research, and human resources related to sago
palms, I would like to recommend Sarawak, Malaysia,
the International Sago Research Center. I hope that mydream will come true in the future for the developmentof the sago palm.
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