core.ac.uk · and lack of basic understanding of the materi-als being processed and the processes...

帯広畜産大学学術情報リポジトリOAK:Obihiro university Archives of Knowledge

' '

Title

Process and Product Analysis of the Village-

Scale Processing of Sweetpotato in the

Philippines

Author(s)

TAN, Daniel Leslie S., MIYAMOTO, Keiji,

ISHIBASHI, Ken-ichi, MATSUDA, Kiyoaki, SATOW,

Tadatoshi, タン, D. L. S., 宮本, 啓二, 石橋, 憲

一, 松田, 清明, 佐藤, 禎稔

Citation 農業機械学会誌, 62(4): 160-172

Issue Date 2000-07

URL http://ir.obihiro.ac.jp/dspace/handle/10322/2957

Rights 農業機械学会

Journal of JSAM 62 (4): 160•`172, 2000Technical Paper

Process and Product Analysis of the Village-Scale

Processing of Sweetpotato in the Philippines

Daniel Leslie S. TAN*1, Keiji MIYAMOTO*2, Ken-ichi ISHIBASHI*3,Kiyoaki MATSUDA*2, Tadatoshi SATOW*2

Abstract

Village level root crop processing system in the Philippines was evaluated using Sweetpotato

(cv. Kogane sengan and Shiro satsuma) as materials. The PRCRTC chipper/grater had more

pronounced power fluctuation in grating than in chipping and peaking during the loading of the

roots. The grinder had the highest energy requirement than the other machines, but the power

fluctuation was relatively stable regardless of the amount of materials loaded. The finisher had

a stable power fluctuation, and its power increased as either the loading rate or rpm was

increased. Size and weight of chips and fineness modulus of grates were affected by the rpm of

the blades. Percent recoveries of dried chips, fine flour and dried grates for Kogane sengan, at 12%

moisture content, were 33.3%, 21.4%, and 30.4%, respectively.

[Keywords] root crops, processing system, village level, chips, flour, grates

I Introduction

In the Philippines, sweetpotato ranks 8th in

total crop production, 10th in value and 7th in

area harvestedl). As food crops, sweetpotato

and cassava rank third next to rice and corn.

From 1984 to 1993, about 95% of sweetpotato

was used for food, and 4.3% was used for

animal feed2).

Sweetpotato can be processed into dried

chips, dried grates, flour and many other food

items3). Sweetpotato flour can replace 10-20%

of the wheat flour. This corresponds to a

potential foreign exchange savings of US

$22 million4). Dried chips from sweetpotato

can either be processed further into flour or be

used as ingredient for animal feed. Fresh

grates are used mainly in making local food

delicacies which are either fried, steamed or

baked like suman and cakes. However, fresh

grates are difficult to transport and store. The

dried grates are therefore produced to replace

the fresh grates.

Village level processing of sweetpotato into

chips, flour and grates is the same as that of

cassava, although cassava is more commonly

used than sweetpotato. Figure 1 shows the

basic steps involved in the processing of root

crop chips, flour and grates. The machines

used for village processing include the chip-

per/grater to chip and grate the roots, the

screw-type presser to remove the excess mois-

ture of the grates before drying, the grinder to

reduce the chips/grates into flour, and the fl-

*1 JSAM Member, United Graduate School of Agricul-

tural Sciences, Iwate University (Obihiro Univ. ofAgric. and Vet. Med.) 11 Nishi-2 Inad-cho, Obihiro080-8555. Japan Tel: 0155-49-5526

*2 JSAM Member, Laboratory of Agricultural Machi-

nery, Department of Agro-Environmental Science,

Obihiro Univ. of Agric. and Vet. Med., 11 Nishi-2,Inada-cho, Obihiro 080-8555, Japan Tel:0155-49-5525

*3 JSAM Member , Laboratory of Food Technology,Department of Bioresource Science, Obihiro Univ.of Agric. and Vet. Med., 11 Nishi-2, Inada-cho,Obihiro 080-8555, Japan Tel: 0155-49-5571

TAN, MIYAMOTO, ISHIBASHI, MATSUDA, SATOW:

Process and Product Analysis of the Village-Scale Processing of Sweetpotato in the Philippines 161

nisher to separate the fine from the coarse

flour. Only the grinder and the finisher are

motor-operated, while the other machines are

either pedal or manually operated. Drying is

done by natural sun-drying. Practically, the

problems encountered in processing cassavaare the same as in sweetpotato because the

same set of equipment is used.

Village level processing systems are impor-

tant in countries like the Philippines especially

because majority of the poor people live in the

rural areas5). While big and efficient process-

ing systems are commercially available, its

high initial acquisition cost, and its high main-

tenance and operating cost seem inappropriate

for village-scale operations. The technology

must suit the needs of the users in the rural

areas. At present, many village-level process-

ing systems are in the rural areas. However,

their operations are inefficient and less produc-

tive, technically because of the crude design,

and lack of basic understanding of the materi-

als being processed and the processes in-

volved. These information are necessary to

design efficient systems. In particular, the vil-

lage level processing system for root crop

chips, grates and flour production has low effi-

ciency and produces low quality products, be-

cause the drying process depends upon the

weather, and the machines used are collections

of available machines to perform each of the

processing operations. Moreover, this process-

ing system is particularly applied to cassava

processing but is used for other root crops like

sweetpotatos6) and arrowroot7). Roa et al8)

reported the production of cassava grates by a

village processor. The processing system bas-

ically involved a grater, a screw-type presser,

sun drying trays and finisher. It was reported

that the quality of the products was unpredict-

able, and the processing system needs im-

provement to increase efficiency.Very little basic information about the vil-

lage level processing system and the products

produced is available. Thus the design of equi-

pment to improve the processing system effi-

ciency and increase product quality would be

difficult. This study therefore aimed to pro-

vide additional information.

The general objective was to evaluate and

analyze the processes involved and the prod-

ucts (chips, flour and grates) in the village

scale processing of sweetpotato in the Philip-

pines. The specific objective was to collect

basic information on the processes used and

Fig. 1 Flow diagram of the basic processes

involved in the village level production

of sweetpotato chips, flour and dried

grates

162 Journal of the Japanese society of agricultural machinery Vol. 62, No.4 (2000)

products. This includes some physical pro-

perties of the products, operating conditions of

the machines, and material balance of the

whole processing system. The drying process

and the chemical properties of the products

are not included in this paper but will be dis-

cussed separately in another paper.

II Materials and Methods

1. Experimental Set-up and Description of

Machines

Some of the machines used in the Philip-

pines were set up in the Agricultural Machin-

ery Laboratory of Obihiro University of Agri-

culture and Veterinary Medicine. These were

the PRCRTC (Philippine Root Crop Research

and Training Center) pedal-operated root crop

chipper/grater, attrition grinder and finisher.

Prototypes of the machines were fabricated

with important machine parts brought from

the Philippines. Frame and body parts were

fabricated and mounted with variable speed

motors. A hopper metering device used to

vary the loading rate of the materials were

also fabricated.

Figure 2 is the PRCRTC chipper/grater

showing the chipper blade with the chips and

grater blades with the grates. The chipper side

of the blade assembly has three sets of blade

symmetrically placed, but alternately aligned

on the surface of the plate with a diameter of

400mm. Each blade has 6 corrugations spaced

at 25mm from each other, and each corruga-

tion has a height of 8mm and 30mm in length.

On the other hand, the grater blade is actually

a punctured metal plate with a diameter of 400

mm. The punctures are spaced at 6.5mm, pro-

trude 1.5mm from the metal surface, and

almost cover the whole surface of the plate.

Figure 3 is the prototype of the attrition

grinder. It is a commercially available grinder,

which is usually used for grinding rice and

corn in the villages, but can be used in grind-

Fig. 2 The PRCRTC chipper/grater with the

chipper and grater blades and products

Fig. 3 Prototype of the attrition grinder



Fig. 4 Prototype of the finisher and its interior

ing different kinds of products. It is described

as the simplest of all the size reduction ma-

chines used for agricultural food products9). It

has two grinding plates: one stationary and

the other rotating.

Figure 4 is the prototype of the finisher

showing the finishing cylinder. The cylinder

has a diameter of 200mm and a length of 500

mm. Its outer surface is covered with mesh

#60 screen. Inside the cylinder is the rotating

stirrer that has a clearance of 3-5mm from the

screen surface. Three fine flour compartments

were made to determine the fine flour distribu-

tion over the length of the finishing cylinder.

2. Materials

Two sweetpotato varieties (namely: Kogane

sengan and Shiro satsuma) were procured from

Kyushu, in November, 1997, and stored under

controlled condition (15•Ž and 59% relative

humidity)10) until use. Table 1 describes some

physical properties of the two sweetpotato

varieties. The roots of Shiro satsuma were

oval, while those of Kogane sengan were long

and slender.

3. Experiments Conducted

(1) Operating performance of the ma-

chines

The output capacity, power consumption

and the revolution per minute (rpm) of main

rotating parts of the machines used were

evaluated. The power consumption and rpm

were determined using the clip-on type power

monitor (SOAR: Energy Monitor 2720) and the

digital tachometer (HIOKI: Tacho Hi Tester

3404), respectively. These data were stored in

the data recorder (TEAC: RD-135T) and

monitored using the digital memory recorder

(NEC: OMNI Light, 8M37). The data gathered

were transferred to the computer using A/D

converter system (TEAC: QuikVu-RD/Win).

A 5kg sample per trial was used to evaluate

the chipper, grater and presser, while 0.5-1.0kg

sample was used to evaluate the grinder and

finisher.

(2) Some physical properties of fresh and

dried chips, and fresh and dried grates

Physical properties (bulk density, size and

shape, and fineness modulus) of fresh and

dried chips and grates, and flour were deter-

mined. Bulk densities of the products were

determined using a 20x20x20 cm stainless steel

container, except for the pressed grates which

was measured using the stainless steel cylin-

der for soil density measurement. The size and

weights were measured using a vernier caliper

Table 1 Physical properties of fresh roots of the two varieties of sweetpotato used in the experiment

Legend: L=length of the roots; D1, D2=diameters of the roots about 2cm from either end; D3=mid-section diameter

of the roots


and electronic balance. For the fineness modu-

lus and average geometric diameter of prod-

ucts, the procedure described by Henderson

and Perry9) was applied. A set of 300mm diam-

eter sieves (mesh sizes: 9.423, 4.699, 2.362, 1.168,

0.589, 0.294, 0.147mm, and pan) and the sonar-

type vibrator (TSUTSUI: SWV-30; SWV-30

AT) were used. The vibrator was set at sonar

frequency of 60Hz, 70% of maximum power,

and 5 minutes operating time. Moisture con-

tent was determined following the procedure

of AOAC11).

(3) Percent recoveries of the different pro-

cessing operations

Five-kilogram samples were used to deter-

mine the recoveries in processing sweetpotato

into chips, flour and grates using the machines

evaluated. Weight before and after each pro-

cessing operation as well as the moisture con-

tents were determined. The material balance

was computed based on these recoveries.

4. Data Analysis

The completely randomized design was used

to statistically analyze the data gathered, and

the Duncan's Multiple Range Test (DMRT)

was used to compare treatment means12).

III Results and Discussion

1. Power requirement

(1) PRCRTC Chipper/GraterWhen the PRCRTC chipper/grater was

operated at 400rpm, the power curves ex-

hibited wider fluctuations and higher average

power consumption in grating than in chip-

ping (Figures 5a and 5b). Between sweet-

potato varieties, Kogane sengan exhibited more

stable power fluctuation than Shiro satsuma

during chipping. During grating, the curve

pattern of the two varieties was similar, but

the average power for Shiro satsuma was ap-

parently higher. This distinction is apparentlydue to differences in varietal characteristics.

This may include, among other factors, the

starch and fiber contents, which may or may

not the same for the two varieties. This may

include, among other factors, the starch and

Fig. 5 Samples of the typical power curves of the machines during operation



Table 2 Performance of some machines used during the testing at certain rpm of the blades (chipper/

grater), disc plates (grinder), stirrer (finisher) for sweetpotato

fiber contents, which may not be the same for

the two varieties. Chemical analysis of the

samples used in the experiments showed that

the starch content at bone dry weight of

Kogane sengan (71.6%) was higher than that of

Shiro satsuma (66.3%), and the fiber content

was lower for Kogane sengan (1.7%) than Shiro

satsuma (2.1%). The exact reason for the differ-

ence, however, can only be established if a

thorough evaluation is conducted to deter-

mine the factors contributing to the differ-

ences in the power requirement, which was

not covered in this study.

The maximum power for Shiro satsuma

occurred every time the roots were loaded to

the hopper, wherein 1.47kW power was

recorded during the grating, and only 0.86kW

for the chipping (Table 2). The average power

computed for the grating was 0.92kW and

only 0.68kW for the chipping. The blade rpm

slowed down from 400rpm (operating without

load) to about 390rpm (operating with load),

both for chipping and grating. The net aver-

age power for grating (0.35kW) was about

three times that for chipping (0.11kW). The

grating capacity (238kg/h), however, wasalmost half of the chipping capacity (479 kg/h).

In terms of the net energy required to proc-

ess 100kg of materials per hour, chipping oper-

ation has the lowest (0.023kW-h/100kg for

Shiro satsuma and 0.020kW-h/100kg for

Kogane sengan) as compared to the other pro-

cessing operations evaluated. The average

torque for chipping was 15.8 N-m and 16.6 N-m,

for Kogane sengan and Shiro satsuma respec-

tively, which was lower than grating at 21.5

N-m (Kogane sengan) and 22.5 N-m (Shiro

satsuma).

(2) Attrition grinder

Table 2 shows that grinding Kogane sengan

chips consumed less power than grinding

Shiro satsuma chips. The same trend was ob-

served in chipping and grating. The average

power in grinding Shiro satsuma chips was 0.86kW with maximum and minimum recorded

power of 1.07kW and 0.72kW, respectively.For Kogane sengan the average power was

about one-half to that of Shiro satsuma 0.48kW

with maximum and minimum recorded power

of 0.66kW and 0.35kW, respectively. This

showed significant differences in the grinding

characteristics of the two sweetpotato

varieties. Power fluctuation of the attrition

grinder was relatively stable except during the


Table 3 Net power (kW) consumption and average rpm of the finisher measured at three different

loading rates and three different rpm values (first grinding of Shiro satsuma chips)

Note: Values with the same letter in the same column are not significantly different from each other at 5% level by

DMRT

initial loading of the chips as shown in Figure

5c. Grinding Shiro satsuma chips used the high-

est net power of 0.57kW as compared to the

other processing operations. The net energy

requirement was computed to be 1.78 kW-h/

100 kg sample. The average torque was 6.5

N-m and 11.8 N-m for Kogane sengan and Shiro

satsuma, respectively.

(3) Flour Finisher

Table 2 showed that the finisher when

operated at 1000rpm and loading rate of 44kg/

h had a net average power of 0.06kW both for

Kogane sengan and Shiro satsuma. This is

translated into 0.13kW-h/100kg of materials

processed. Although it has the lowest net aver-

age power consumption among the processing

operations, its capacity was lower compared to

chipping and grating operations. At three

different loading rates (44, 70 and 102kg/h),

and three stirrer rpm (800, 1000 and 1200 rpm),

Table 3 showed a significantly increasing

power as the loading rate was increased in all

rpm values, but highest at the 1200rpm set-

ting. Figure 5d shows the typical power curve

during the finishing operation. The power

steadily rose until it reached the maximum

and leveled-off. The rpm of the stirrer, on the

other hand, decreased as the load increased,

indicating an increasing torque application.

Fine flour gathered from the three fine flour

compartments indicated that almost all of the

fine flour was gathered in the first (90.9%) of

the three compartments. The remaining

amount of 7.3% and 1.8% were distributed in

the second and third compartments, respec-

tively. The percentage distribution was

almost the same for all the different loading

rates and different rpm settings. This means

that less than half of the total length of the

cylinder might not be necessary for the finis-

hing operation. Therefore, this will allow the

design of a smaller finishing machine.

2. Material Balance

The processing recoveries of the different

operations for Kogane sengan variety shown in

Figure 1 are tabulated in Table 4. When the

existing set-up was used, the fine flour recov-

ery of only 21.4%, which is equivalent to 64.3%

recovery from dried chips, clearly shows that

the system needs further improvement. The

11.7% coarse flour recovered can be processed

further into fine flour, if the right kind of

machine is available. In flour production, the

main problem of increasing the flour recovery

is in the grinding process, where much coarse

flour should be reduced to the minimum.

For dried grates, the main problem is in the

grating operation where a considerable loss of

15% was observed. This loss, however, can be

easily corrected by reducing further the clear-

ance between the blade and the side of the

hopper where the fresh grates pass through.

The final amount of grates produced was

30.4% at 12% moisture level.



Table 4 Material balance in the production of sweetpotato dried chips, flour and grates for 100 kg of

fresh roots (Kogane sengan, MC=03.7%, w.b.)

3. Analysis of products and processes

(1) Chips

The Thai and Malaysian chippers use a cor-

rugated type of blade that produces moderate-

ly uniform chips (4-6mm thick, and 10-80mm

long)13). The PRCRTC chipper/grater also uses

a similar type of blade that produces chips

(Kogane sengan) with average thickness and

weight of 4.8 mm and 1.09gram, respectively

(Table 5). The length of the chips was longer

for Shiro satsuma (38mm) than Kogane sengan

(33mm) which could be due to the different

root diameter of the two varieties in which

Shiro satsuma is bigger than Kogane sengan as

reflected in Table 1. The chip size, however,

was affected by the rpm of the blade. As rpm

of the blade is increased, the average chip size

decreased. There was also a noticeable in-

crease in crumbs at higher blade rpm, which

could result in bigger losses during the drying


Table 5 Physical properties of the fresh and dried chips

process.

For the bulk densities, Kogane sengan has

fresh and dried chips bulk densities of 479

kg/m3 and 330kg/m3, respectively, while Shiro

satsuma has almost the same (fresh and dried

chips bulk densities of 474kg/m3and 336

kg/m3, respectively). This corresponds to

about 31% and 29% reduction for Kogane

sengan and Shiro satsuma, respectively, as

reflected in Table 5.

In village level chips processing in the Phil-

ippines, drying is always done by sun drying

such that good quality chips are seldom pro-

duced. Sun drying of chips usually takes at

least 2 consecutive sunny days to reach to a

safe moisture content level.

(2) GratesProduction of dried grates is quite a difficult

operation in the village level set-up. Manual

operations include pressing the grates to

remove some amount of water, pulverizing

and bringing the grates to an open space for

sun drying. An added difficulty is the manual

handling of the grates because of the relative-

ly smaller size of the grates compared to the

chips.

One of the problems in the village-level

grates processing is the changing size of the

grates. This happens because the grater bladeeasily wears out after continuous use. Newly

installed blade produces grates that are of

different quality than the worn out blade.

The grates produced at the three different

rpm's showed no significant differences, in

percent starch and water removed, amount of

starch in water, and moisture content of pre-

ssed grates (Table 6). However, the fineness

modulus decreased with an increase in rpm.

This implies that the grate size changes as the

blade rpm changes, but the limits have yet to

be determined.

Fresh grates usually have more than 60%

moisture content. Pressing the grates can

reduce the moisture to about 40%. For grates

processing, excess moisture must be removedby pressing before drying to avoid formation

of lumps that will be difficult to disintegrate

after the grates have dried. Also, pressed

grates should be pulverized before drying.Bulk densities of the fresh, pressed,

pulverized, and dried grates are different fromeach other (Table 7). Except for the bulk den-

sity of the fresh grates, the bulk densities of

the pressed, pulverized and dried grates were

higher for Kogane sengan than Shiro satsuma.

The dried; grates had a fineness modulus of

2.40, as shown in Table 8. Table 8 also shows

that the size distribution of the grates peaked

at 0.589mm mesh size with about 42% of the

amount retained. Also, a little amount of

6.54% passed through the #100 mesh (0.147

mm).

(3) FlourThe problems to be addressed in the village

level processing system are (1) improving, the

flour quality, and (2) increasing the fine flour



Table 6 Characteristics of chips and pressing characteristics of grates produced at three different

blade rpms of the PRCRTC chipper/grater

Note: Values with common letters in the same column are not significantly different from each other at 5% level by

DMRT.

Table 7 Bulk densities (BD, kg/m3) of Sweetpotato grates and flour at different processing stages with

their moisture contents (%, w.b.) in parenthesis

Note: Values with the same letter in the same row are not significantly different from each other at 5% level byDMRT.

Table S Percent retained in the sieves, fineness modulus (FM) and average diameter (mm) of the

materials

Note: Average diameter (D) in mm was computed using the formula9): D-0.0041*25.4*(2)FM


recovery. Good quality flour is seldom ob-

tained because the chips are always dried

using the sun. On the other hand, the fine flour

recovery is low because the grinding machine

is an attrition grinder. The attrition grinder

has only a maximum fine flour recovery of less

than 90% for two grinding and finishing

passes for cassava, and much lower for

sweetpotato. Studies in Colombia using the

wheat flour roller mill to produce cassava flour

showed a recovery of 83-98%13. For cassava

flour processing in the Philippines, Orias and

Tan14) reported a recovery of about 90% flour

from a combined attrition grinder and finisher

machine.

In Table 8, the fine flour (FM=0.28) pro-

duced after the first pass of the grinding and

finishing operations was finer than that of the

second pass (FM=0.45), while the coarse flour

of the first pass (FM=2.62) was coarser than

that of the second pass (FM=1.95). This is

because the first grind fine flour which came

from chips has more fine or starch particles

than the second ground fine flour, which came

from the coarse flour of the first grind chips.

The amount of materials that passed through

the #100 mesh into the pan for the first pass

(74.3%) was higher from the second pass

(62.4%).High bulk density of 731kg/m3 was ob-

served in the second ground coarse flour from

Shiro satsuma (Table 7). However, this value

was not significantly different from the bulk

densities of the first grind coarse flour and the

second grind crude flour. The first grind fine

flour has the lowest density of 595kg/m3,

which was significantly different from the

second grind fine flour of 626kg/m3. Appar-

ently for Shiro satsuma, the coarse particles are

heavier than the fine particles. For Kogane

sengan, highest bulk density of 643kg/m3 of

the second grind crude flour was noted. How-

ever, this value was not significantly different

from the second grind fine and coarse flour

with bulk densities of 629 and 622kg/m3, re-

spectively. The lowest bulk density of the first

grind fine flour was 571kg/m3. Bulk densities

of Kogane sengan were relatively lower than

Shiro satsuma.

IV Conclusion and Recommendation

1. Conclusion

Basic information (both on the processes and

products) in the village level processingsystem has been established.

(1) The PRCRTC chipper/grater, both for

chipping and grating, has a pronounced power

fluctuation and peaking during the loading of

the roots. Energy required for grating was

higher than chipping. The attrition grinder

has a stable power regardless of the kind and

amount of material loaded to the hopper. It

the highest energy requirement among the

machines evaluated. The finisher power con-

sumption increases with an increased loading

rate in all the stirrer rpm range (800-1200rpm).

Over the length of the finishing cylinder, the

first compartment (1/3 of the length of finis-

hing cylinder) received about 90% of the fine

flour, therefore allowing a reduction in size of

the cylinder by at least one half.

(2) The average weight of the chips is

affected by the rpm of the blade. Average

length of the chips is higher for Shiro satsuma

(38mm) than Kogane sengan (33mm). Percentreduction in size from fresh to dried chips

ranged from 7 to 38.5%, with Shiro satsuma

exhibiting generally higher reduction. Bulk

density of fresh sweetpotato chips is slightly

higher for Kogane sengan (479kg/m3) than for

Shiro satsuma (474kg/m3). For dried chips,

however, the bulk density of Shiro satsuma

(336kg/m3) is slightly higher than that of

Kogane sengan (330kg/m3). The bulk densities

of fresh, pressed, pulverized and dried grates

were generally different from each other and



between varieties. Shiro satsuma showed

higher fresh grates bulk density, but lower

bulk densities for pressed, pulverized and

dried grates than Kogane sengan. The bulk

densities for the first and second grind fine

flour of Shiro satsuma were lower than those of

the first and second grind coarse flour. For

Kogane sengan, the bulk densities of the second

grind fine and coarse flour were higher than

the first grind fine and coarse flour. The fine

flour of the first grind chips was finer than that

of the second grind materials, while the coarse

flour of the first grind chips was coarser than

the second grind materials. The grates, has

fineness modulus of 2.40 which is between the

fineness modulus of the first and second

ground flour (2.62 and 1.95, respectively).

(3) With the existing village scale root crop

processing system, the recoveries of driedchips, fine flour, and dried grates for .Kogane

sengan, at moisture content level of 12% (wet

basis) were 33.3%, 21.4%, and 30.4%, respective-

ly. A considerable loss of 11.7% in the form of

the coarse flour that greatly contributed to the

fine flour recovery of only 64.3%, from dried

chips.

2. Recommendations

The following are recommendations to fur-

ther improve the processing system

(1) For flour, it is necessary to find ways toincreasing the milling efficiency of the system,

so that fine flour recovery from dried chips

will increase to more than 95% from the pres-

ent 64.3%. Also, a processing method to pro-

duce flour either from chips or from grates

should be evaluated technically and ec-

onomically.

(2) For grates, the grater blade should be

standardized to maintain the quality of the

grates. A continuous flow processing system

should be designed for the village-scale pro-

cessing set-up. This requires testing of anoth-

er method to extract the water from the grates

like expeller and spinner machines.

References

1) Palomar, M.K., Bulayog, E.F., and Truong, Van Den

Sweetpotato research and development in the Philip-

pines. In: CIP, 19892) Bureau of Agricultural Statistics: 1994

3) Truong, Van Den. State of the Art: Processing and

utilization of cassava and sweetpotato for food. Paper

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「技術論文」

フィリピンにおけるサツマイモの小規模加工法と

製品

D.L.S.タン*1・宮本啓二*2・石橋憲一*3・松田清

明*2・佐藤禎稔*2

要旨

フィリピンで行われている根菜類の小規模加工

法を2品種のサツマイモ(コガネセンガンとシロ

サツマ)を原料として検討した。原料はフィリピ

ン根菜類研究・訓練センター(PRCRTC)が開発

したチッパ・グレイタで処理されるが,グレイテ

ング(すりおろし)に要する電力はチッピングよ

りも高く,その変動は著しく大きい。粉砕機で乾

燥チップなどを処理する場合,電力の変動は供給

量に関係なく安定していたが,エネルギ消費量は

チッパ・グレイタや精選機よりも大きい。精選機

の電力はサッマイモ粉の供給量と回転数が高くな

るほど増加した0乾燥チップの大きさと質量およ

び乾燥グレイツの粒度係数は刃の回転数に影響さ

れる。コガネセンガンの場合,乾燥チップ,乾燥

粉および乾燥グレイッの回収率は12%水分換算

で,それぞれ33.3%,21.4%,30.4%であった。

[キーワード]根菜類加工システム,村落レベル,チッ

プ,粉,グレイツ

*1会員,帯広畜産大学畜産学部畜産環境科学科(岩手大

学大学院連合農学研究科)*2会員,帯広畜産大学畜産学部畜産環境科学科

*3会員,帯広畜産大学畜産学部生物資源科学科

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