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Glucose syrup production from Indonesian palm and cassava starch
Food Research International,Vol. 28, No. 4, pp. 379-385, 1995 Elsevier Science Ltd Copyright 0 1995 Canadian Institute of Food Science and Technology
Printed in Great Britain. All rights reserved 0963-9969195$9.50 + .OO
ELSEVIER 0963-9969(95)00010-O
Glucose syrup production from Indonesian palm and cassava starch Julius Pontoh & Nicholas H. Low* Department of Applied Microbiology and Food Science, University of Saskatchewan, Saskatoon, SK, Canada S7N 0 WO
Six palm starch samples and one cassava starch sample from Indonesia were converted into glucose syrup with comparison to a commercial corn starch, sample. The conversion was carried out by both liquefaction using a-amylase from B. stearothermophilius and saccharification using glucoamylase from A. niger. The liquefaction time for Metroxylon starch samples was longer than that observed for the other starch samples. Viscosity during liquefaction for palm and cassava starch samples showed the same variation. Based on dextrose equivalent (DE) and high performance liquid chromatography (HPLC) results, starch conversion to glucose for five of the palm and the cassava starch sample was equivalent to that observed for the corn starch sample. Starch conversion to isomaltose and maltose for the palm and cassava starch samples was equivalent to that for the corn starch sample. In general, starch conversion to higher oligosaccharides (DP-3 to DP-7) for the palm and cassava starch samples was higher than that observed for the corn starch sample. Therefore, based on the liquefaction time, percent conversion to glucose and total oligosaccharides, all palm and cassava starch samples, except for one A. pinnata starch sample, could be used for glucose syrup production. Keywords: glucose syrup, caloric sweetener, starch, corn, cassava, palrnkago,
(Y-
amylase, glucoamylase, enzymic process.
Sulawesi, and sugar palm is plentiful in all regions of South East Asia (Mogea, 1991). It has been reported that sago starch could be used as raw material for glucose syrup production (Arbakariya et al., 1990; Govindasamy et al., 1992), however, detailed results have not been reported for this conversion. The purpose of this research was to study the conversion of six palm and one cassava starch sample from Indonesia into glucose syrup with corn starch as a standard.
INTRODUCTION World high fructose syrup (HFS) consumption has been continually increasing due to its extensive use in beverages and processed foods (White, 1992). HFS is produced by the hydrolysis of starch into glucose followed by isomerization into fructose. Therefore, glucose syrup which is also referred to as dextrose syrup, is an intermediate in HFS production. In general, corn starch is the main raw material for glucose syrup production, however, in Indonesia, cassava starch is most often used (White, 1992). Several palm starches traditionally used as staple foods in South East Asia are potential raw materials for glucose syrup production. These include: sugar palm (Arenga pinnata Merr), aren sagu (A. microcarpa Becc.) and sago palm (Metroxylon sagu Roettboell; h4. rumphii Mart.) (Mogea, 1991). There are approximately one million hectares of sago palm forest in Indonesia (Flach, 1983). Aren sagu is abundant in North *To whom correspondence
MATERIALS
AND METHOD
Materials Two sago (M. rumphii, I and II) starch samples and one ‘aren sagu’ (A. microcarpa) starch sample were obtained from starch processors in Manado, Indonesia. One sag0 (M. sagu), one sugar palm (A. pirmata, II) and one cassava starch sample were obtained from a small commercial plant in Bogor, Indonesia. One sugar
should be addressed. 379
380
J. Pontoh, N. H. Low
palm (A. pinnata, I) starch sample was processed by J. Pontoh employing traditional processing methods. Complete starch sample preparations are described elsewhere (Pontoh & Low, 1995). A commercial corn starch sample was purchased locally (Best Foods Canada Inc.). a-Amylase for liquefaction was supplied by Enzyme Bio-Systems Ltd., (Englewood Cliffs, NJ, USA; G-ZYME G 995; produced by Bacillus stearothermophilus) with an activity of 4100 units/g (specific gravity: 1.15-1.20 g/ml). Glucoamylase for saccharification was also supplied by Enzyme BioSystems Ltd, (G-ZYME G 990; produced by Aspergillus niger) with an activity of 200 units/ml. Unless mentioned, other reagents were analytical grade or better. Liquefaction and saccharification Each sample (weight equivalent of 60 g starch) was weighed directly into the 400 ml batch reactor vessel (Figure 1) and HPLC grade water was added to bring the total weight of slurry to 200 g. The resulting slurry was stirred and the pH was adjusted to 5.7 by the addition of either 1N HCl or 1N NaOH. Following stirring of the slurry (~5 min) 35 ~1 of a-amylase was added to the vessel and the resulting slurry was heated to 80°C (oil bath; Ikamag, Rose Scientific, Edmonton, AB, Canada) and maintained at this temperature for 3 min to partially reduce the viscosity. The temperature was then rapidly increased to 106°C (+l’C; the approximate time to reach this temperature was 2 min) and maintained at this temperature for 5 min, and then the temperature was rapidly reduced to 95°C (approximately in 1 min). This temperature was maintained until a final dextrose equivalent (DE) of 12.5-15.0 was reached (30-90 min, depending on the sample). Following liquefaction the resulting syrup was cooled to 60°C by immersing the reactor vessel in ice water. The syrup was adjusted to pH 4.5 by the addition of 1 N HCl and transferred to a 1 1 Wheaton bioreactor (Wheaton Instrument, Millville, NJ, USA) which was maintained at 60°C using a Haake D3-G circulating thermostat (Haake Mess-Technik Co., Berlin, Germany) and 60 ~1 of glucoamylase was added. Samples were continually
stirred using a magnetic stirrer and aliquots were removed at time intervals of 24,48,72 and 96 h for DE and total carbohydrate analysis. Six replicates for corn and four replicates for each palm and cassava starch sample were run. Starch slurry viscosity The effect of a-amylase on starch slurry viscosity was determining using a Brabender viscoamylograph (C.W. Brabender Instruments Inc., South Hackensack, NJ, USA) maintained at 75 rpm. Viscosity was determined on a 30% (w/w) starch slurry with the addition of 87.5 ~1 of a-amylase per 500 ml of slurry. Viscosities were determined using the following viscoamylograph temperature program: constant-preheating at 30°C for 5 min gradient heating from 30 to 95°C for 44 min, and constant heating at 95°C for 30 min. Determination of dextrose equivalent (DE) Samples were analyzed using the Association of Official Analytical Chemists (14th edition, 1984) method 31.035 (Lane-Eynon method). A 0.5 ml sample aliquot was transferred to a 100 ml volumetric flask and made up to volume by the addition of HPLC grade water. Five ml of Fehling A solution (69.278 g CuS04.5H,0 in 1 1 distilled water) and 5 ml of Fehling B solution (346 g KNaC4H,06 and 100 g NaOH in 1 1 HPLC grade water) were added to a 250 ml erlenmeyer flask and 3 drops of 1% (w/v) methylene blue solution was added. The resulting solution was heated and maintained at boiling for 2 min. This solution was then rapidly titrated (< 1 min) with the sample solution until the end point was reached (colorless solution). Total dextrose or glucose calculated as reducing sugar was obtained from the AOAC conversion table and dextrose equivalent was calculated using the following equation: weight of glucose (from the conversion table)
x 100 (1)
weight of dry syrup sample
High performance liquid chromatography (HPLC) analysis
Fig. 1. Diagram of liquefaction apparatus consisting of: bath reactor (a); thermometer (b); pressure valve (c); oil bath (d); and hot plate (e).
Samples were analyzed on a Dionex Bio LC 4000 gradient liquid chromatograph (Dionex, Sunnyvale, CA, USA) with a Dionex 10 pm Carbo Pat PA1 pellicular anion exchange column (4 X 250 mm). A 100 ~1 sample loop was used for analysis and the mobile phase flow rate was 1.0 ml/min. Carbohydrates were detected by a pulsed amperometric detector (PAD; Dionex) with a gold electrode and triple pulsed amperometry at a sensitivity of 10 K. The electrode was maintained at the following potentials and duration: E, = 0.05 V (t, = 120 ms); E2 = 0.80 V (t2 = 120 ms); E3 = -060 V (t3 = 420 ms).
Glucose syrup production from Indonesian palm and cassava starch
Sample preparation involved appropriate dilution with HPLC grade water (glucose: 1 in lo4 ml; oligosaccharides: 1 in 25 ml) followed by passage through a 0.20 pm syringe filter (Corning Glass Works, Corning, NY, USA). A standard curve for glucose was prepared using a series of glucose (BDH, Toronto, ON, Canada) solutions which varied in concentration from 30 to 50 ppm, in 3 ppm increments. Standard curves for oligosaccharides were prepared from a stock oligosaccharide solution which contained 5.0 mg of isomaltose, 5.8 mg of maltose, 7.6 mg of maltotriose, 7.3 mg of maltotetraose, 7.8 mg of maltopentaose, 7.4 mg of maltohexaose and 7.9 mg of maltoheptaose (all from Sigma, St. Louis, MO, USA), respectively, in 50 ml of HPLC grade water. Dilutions ranged from 10 to 50 (v/v basis). Glucose elution was afforded with an isocratic mobile phase of 80 mM NaOH, and the following gradient elution program was used to achieve oligosaccharide separation: 100 mM NaOH for 8 min; from 8 min to 48 min a linear gradient of 250 mM sodium acetate (NaOAc) was used; the column was then regenerated by the immediate addition of 300 mM NaOH (30 min), followed by column reequilibration with 100 mM NaOH (30 min).
381
Table 1. Time required to reach a dextrose equivalent of 12-15 at 95°C (liquefaction time) for starch samples
Liquefaction time (min)
Starch sample Corn0 Cassava”
30 30
Metroxylon rumphii I” Metroxylon rumphii II” Metroxylon sagu” Arenga microcarpa’ Arenga pinnata I” Arenga pinnata II”
60
50 90 30 40
40
‘Based on three determinations.
time of A. microcarpa was similar to that of corn, but all other palm starch liquefaction times were higher. Metroxylon starches had the highest liquefaction times (50-90 min) and Arenga starches the lowest (30-40 min). Reeve (1992) suggested that the presence of an antiamylase in sago starch would slow the liquefaction process. However, molecular architecture of the starch could also have a substantial effect on liquefaction.
Temperature
Experimental
design and statistical
96°C
analysis
Experiments were set up in a randomized block design. Analysis of variance was used in order to examine the effect of starting material (starch) on glucose syrup production. Dunnet test (Montgomery, 1984) was used to compare the differences between glucose syrup produced from corn and those from palm and cassava starch. Four replicates for each of the Indonesian starch samples and six replicates for corn were processed in two groups (blocks). The experimental data (DE and carbohydrate composition of glucose syrup after 72 h saccharification time) was processed using StatView 4.01 (Abacus Concepts, Berkeley, CA, USA) at a 5% significance level.
RESULTS Liquefaction
Time
(minutes)
Temperature 96°C
-r B
AND DISCUSSION time
Liquefaction time, the time required to reach a DE of 12-l 5, for each starch sample is shown in Table 1. The liquefaction time observed for corn starch in this study (30 min) was considerably shorter than that reported by Fullbrook (1984) of 60-90 min (industrial practice). This time difference was most likely due to the increased mixing efficiency of the laboratory scale liquefaction. Liquefaction time for cassava starch was equivalent to corn starch, and the liquefaction times for palm starch varied from 30 to 90 min. The liquefaction
-
A.rrlkmap
-
A.phm/
-
A.@m!a//
--m-
Corn
--
10
20
30
40
Time
60
60
70
80
(minutes)
Fig. 2. Determination of starch viscosity during liquefaction with a-amylase using a Brabender viscoamylograph with the following temperature program,: constant-preheating at 30°C for 5 min; gradient heating from 30°C to 95°C for 44 min, and constant heating at 95°C for 30 min. (A) h4. rumphii I, M. rumphii II, M. sagu, Corn and Cassava; (B) A. microcarpa, A. pinnata I, A. pinnata II, Corn and Cassava.
J. Pontoh, N. H. Low
382
For, example, it has been reported (Takeda et al., 1989) that the molecular weights of sago starch amylose and amylopectin are 4-7 times higher than that of corn and cassava starch. This increase in molecular weight lengthens the liquefaction time. The significant difference in liquefaction times between M. sagu and M. rumphii might also be due to damaged M. rumphii granules as observed by scanning electron microscopy (SEM; Pontoh & Low, 1995.
-Corn -cassaVa ._ -
-
M.sagu
M.nnphiiI
-
A.mlcmcalp9 A.pinmtaI
M.lw@lllII
-
A.@naall
I 24
Viscosity during liquefaction
49
72
96
Sacchariiication Time (Hours)
Figure 2 shows the viscosity profile of each starch sample under liquefaction conditions. During liquefaction, cassava had the lowest and A. microcarpa the highest viscosity. Compared to corn, three palm starch samples had lower and three higher liquefaction viscosities. Low liquefaction viscosity indicates a greater susceptibility of the granule to enzymic attack. Of the Metroxylon starch samples only M. rumphii I exhibited a lower viscosity than corn. This may have been due to the observed (SEM) extensive granule damage of this starch (Pontoh & Low, 1995). Of the Arenga starch samples only A. pinnata I had a higher liquefaction viscosity than corn. This may have been due to the presence of fragments on the surface of these starch granules (Pontoh & Low, 1995). Therefore, Metroxylon samples have a higher viscosity than corn, whereas, Arenga samples had lower viscosities under these liquefaction conditions. Low viscosity could result in reduced energy consumption during liquefaction. Dextrose equivalent Figure 3 presents the DE values reached during saccharification. Each of the syrups, except cassava, reached its optimum DE value between 48 and 72 h (corn at 72 h). The cassava sample reached its optimum DE in the shortest saccharification time (24 h). The mean DE value obtained for corn was 96.0 (Table 2). This value was slightly lower than that nor-
Fig. 3. Change in dextrose equivalent of syrups during saccharification with glucoamylase at 60°C for each starch sample. mally obtained in industrial practice of 97 to 98 (Reeve, 1992). Results indicated that the DE value obtained for corn was not significantly different (P > 0.05) from those obtained for each of palm starch samples, except for A. pinnata 1. Therefore, each of these samples was equivalent to corn as a raw material for glucose syrup production under these experimental conditions. The DE value obtained for A. pinnata I was significantly lower (P I 0.05) than that obtained for corn. Therefore, A. pinnata I would be a poorer starch source than corn for glucose syrup production.
CARBOHYDRATE ANALYSIS BY HPLC Glucose Percent conversion of starch into glucose for each sample increased during saccharification (Figure 4). The optimum conversion time for each of the palm starch samples in this study ranged from 48 to 72 h. The optimum saccharification time reported by Fullbrook (1984) and Reeve (1992) for industrial glucose syrup production from corn is 48 to 72 h. The mean percent conversion for corn starch at 72 h was 105.5% (Table 2). This value was equivalent to
Table 2. Mean value for dextrose equivalent and percent conversion (g/g) of starch to gh~cose, isomaltose, maltose and alto&se saccharification time of 72 h at 60°C
Starch sample Comb Cassava’ M. rumphiif M. rumphii II’ M. sagu’ A. microcarpaC A. pinnata 1’ A. pinnata II’
Dextrose equivalent
Glucose
Isomaltose
Maltose
Maltotriose
96.0 f 1.9 97.2 + 2.3
10550 f 2.30 105.20f 2.80
1.16 f 0.25 1.60 f 0.10”
1.11 It 0.07 1.40 f 0.06”
0.72 f 0.10 0.87 f 0.06” 1.05 f 0.06”
94.5 AZ1.5
103.50 f 1.9w
1.41 f 0.27
1.40 f 0.15”
94.4 f 1.6
104.70f 1.30
1.28 f 0.10
1.33 f 0.2W
1.03 f 0.04O
95.3 f 1.4 95.6 + 1.1 86.2 f 1.1”
104.50 f 1.30 104.20 f 2.00 94.00 zk3.60”
1.48 f 0.13 1.35 f 0.15 1.21 + 0.06”
1.37 f 0.11” 144fO~ll” 1.48 f 0.21”
95.6 rt 1.1
0.53 f O.OY 1.09 f 0.04” 1.38 f 0.10”
104.60f 1.50
1.33 f 0.05
1.46 f 0.18”
1.10 f 0.07”
“Significantly different from corn at the 5% level. bBased on six determinations. cBased on four determinations.
at a
Glucose syrup production from Indonesian palm and cassava starch
-
24
48
72
96
383
A
96
72
48
24
Saccharification Time (Hours)
Saccharificafion Time (Hours)
Fig. 4. Percent change in starch sample conversion to glucose (g/g) during saccharification with glucoamylase at 60°C.
Fig. 5. Percent change in starch sample conversion to isomaltose (g/g) during saccharification with glucoamylase at 60°C.
96.1% of the total carbohydrate content. This value agreed with industrial starch conversion results of 95-96% (Fullbrook, 1984; Reeve, 1992). Statistical analysis of these results indicates that mean percent starch conversion to glucose for cassava, M. rumphii II, M. sagu, A. microcarpa and A. pinnata II were not significantly different (P > 0.05) at 72 h ofsaccharification when compared to corn (Table 2). Therefore, each of these samples were equivalent to corn with respect to starch conversion to glucose under these experimental conditions. Comparison of A. pinnata I and M. rumphii I values with corn showed that their conversion was significantly lower (P I 0.05) after 72 h of saccharification. However, the DE value of M. rumphii I was not significantly lower (P > 0.05) than that of corn (Table 2).
with respect to isomaltose content. Isomaltose content of cassava was significantly higher (P 5 0.05) than that found for corn. The higher isomaltose content for cassava may have been due to the transglycosylation action of glucoamylase and/or more branching in the cassava starch sample (Nikolov et al., 1989; Rastall et al., 1991).
Oligosaccharides Oligosaccharides are considered to be impurities which require removal to produce a high quality glucose syrup. The major oligosaccharides found in these glucose syrup were isomaltose, maltose and maltotriose. Other oligosaccharides, DP4 (DP = degree of glucose polymerization; i.e. DP-4 = tetraose) to DP-7 were present in low concentrations.
Maltose Figure 6 presents the conversion of starch into maltose during saccharification. Maltose content decreased significantly (P I 0.05) during the first 48 h of saccharification and then became constant. This decrease in concentration was due to the hydrolytic action of glucoamylase. Prolonged saccharification resulted in maltose synthesis via transglycosylation (Nikolov et al., 1989; Rastall et al., 1991) which appeared to offset maltose hydrolysis. The mean percent conversion for corn starch at 72 h this was 1.11% (Table 2). This value was equivalent to 1.01% of the total carbohydrate content. This value was slightly lower than the range reported by Fullbrook (1984) and Reeve (1992) of 1.2-2.0%. Statistical analysis of these results indicates that the six palm samples and cassava sample had a significantly higher (P I 0.05) maltose content than corn starch (Table 2).
Isomaltose Figure 5 presents the conversion of starch into isomaltose during saccharification. Isomaltose content for each starch sample increased during saccharification and this increase was due to the limited action of glucoamylase on branch points and the transglycosylation action of this enzyme. The mean percent conversion for corn starch at 72 h was 1.16% (Table 2). This value was equivalent to 1.05% of the total carbohydrate content. This value agreed with the range reported by Fullbrook (1984) and Reeve (1992) of l&2.0%. Statistical analysis of the mean results indicates that the six palm starch samples were not significantly different (P > 0.05) than corn
I P
2.0
r” 0
1.6
6 ._
/
0.8 1.2
e p”
0.4
--t -cassaVa
Corn
48
-
A.mhcqa M.aagu
-
A.pinnataI
72
Sacchariiication Time (Hours)
Fig. 6. Percent change in starch sample conversion to maltose (g/g) during saccharification with glucoamylase at 60°C.
J. Pontoh, N. H. Low
384
.fj
5 A.pimhlII
-
A.pidl
-
M.n#@liI
-
A.miuocarpe
---C
M.nrdiiII
-
tAmgIl
2.0
8 5
-
4
-
3
Apirmcrll
2
1
“.”
I
40
24
Sacchariiication
72
48
24
96
Saccharification
Time (Hours)
7. Percent change in starch sample conversion to maltotriose (g/g) during saccharificationwith glucoamylase at 6O’C.
Fii.
96
72
Time (Hours)
Fig. 8. Percent change in starch sample conversion to total DP-4 to DP-7 (g/g) during saccharification with glucoamylase at 60°C.
Maltotriose
nature of these particular oligosaccharides which would result in slow hydrolysis by glucoamylase (Hebeda, 1993). It is also possible that oligosaccharide hydrolysis (DP-4 to DP-7) is offset by synthesis via transglucosylation (Nikolov et al., 1989). Table 3 presents the percent conversion of starch to DP-4, DP-5, DP-6 and DP-7. Statistical analysis of these results indicates that mean percent starch conversion to DP-4 to DP-6 for corn was lower (P I 0.05) than that obtained for cassava, A4. rumphii and Arenga samples. However, total DP-4 to DP-6 of M. sagu was equivalent to that of corn. Percent conversion to DP-7 for corn was significantly lower than that for M. rumphii and A. pinnata I samples. Therefore, corn and M. sagu would be equivalent raw materials for glucose syrup production with respect to total DP-4 to DP-7 content.
Figure 7 presents the conversion of starch into maltotriose during saccharification. Percent conversion of starch to maltotriose slightly decreased during saccharification (2496 h). Percent conversion for corn starch at 72 h was 0.72% (Table 2). This value was equivalent to 0.65% of the total carbohydrate content. This value agreed with that reported by Reeve (1992) of 04-0.8%. Statistical analysis of these results indicates that mean percent starch conversion to maltotriose for corn was significantly lower (P I 0.05) than that for cassava, M. rumphii, A. microcarpa and A. pinnata samples. However, corn maltotriose content was significantly higher (P I 0.05) than that observed for M. sagu. DP-4 to DP-7 Total DP-4 to DP-7 content for each starch sample decreased significantly (P I 0.05) during the first 48 h of saccharification and then became constant (Figure 8). This decrease in concentration was due to the hydrolytic action of glucoamylase. Prolonged saccharification did not reduce total DP-4 to DP-7 concentration. This could be due to the highly branched
CONCLUSIONS In general, dextrose equivalent data agreed with the conversion of starch to glucose. Based on these results, it can be concluded that all palm and cassava starch samples except A. pinnatu I could be used for glucose
Table 3. Mean value for percent conversion (g/g) of starch to DP-4, DP-5, DP-6 aud DP-7 at a saccharification time of 72 h at 60°C Starch sample corn* Cassava’ M. rurnphif M. rumphii
II’
M. sag& A. microcarpac A. pinnata 1’ A. pinnata II’
DP-4
DP-5
DP-6
DP-7
0.14 f 0.01 0.20 f 0.03”
0.15 AZ 0.01 0.30 * 0.04”
0.18 + 0.01 0.30 f 0.05”
0.19 f 0.01 0.26 f 0.03
0.21 f 0.01”
0.32 + 0.04”
0.29 f 0.02’
0.34 f 0.03”
0.20 f 0.00” 0.13 f 0.00
0.36 f 0.02” 0.14 + 0.03
0.30 + 0.02” 0.21 f 0.02
0.34 + 0.03” 0.27 f 0.01
0.23 + 0.02”
0.30 * 0.02”
0.27 f 0.02”
0.32 f 0.03”
0.30 + 0.01”
0.54 f 0.03”
0.42 f 0.05”
0.48 f 0.08
0.23 f 0.02”
0.38 + 0.03”
0.31 f 0.01”
0.32 f 0.03
“Significantly different from corn at the 5% level. *Based on six determinations. ‘Based on four determinations.
Glucose syrup production from Indonesian palm and cassava starch syrup production. Under these liquefaction conditions, Metroxylon samples showed higher viscosity which may translate to higher energy input, whereas, Arenga samples showed lower viscosity. The liquefaction time for Metroxylon samples were also longer than that observed for corn. Palm and cassava glucose syrup had slightly higher oligosaccharide contents than corn that may require purification. Therefore, some minor modifications in commercial glucose syrup production for Indonesian palm starch may be required.
REFERENCES Arbakariya, A., B. Ali-Asbi & R. Norjehan (1990). Rheological behavior of sago starch during liquefaction and saccharification. In Enzyme Engineering 10, eds H. Okada, A. Tanaka & W. Blanch. Annals of the New York Academy of Sciences, Vol. 613, New York, pp. 610-13. Flach, M. (1983). The Saga Palm. FAO Plant Production and Protection, Rome, Paper 47. Fullbrook, P. D. (1984). The enzymic production of glucose syrups. In Glucose Syrups: Science and Technology, eds S. Z. Dziedzic & M. W. Kearsley. Elsevier Applied Science, London, pp. 65-115. Govindasamy, S., Oates, C. G. & Wong, H. A. (1992). Characterization of changes of sago starch components during hydrolysis by a thermostable alpha-amylase. Carbohydrate Polymers, 18, 89-100.
385
Hebeda, R. E. (1993). Starches, sugar and syrups. In Enzymes in Food Processing, eds T. Nagodawithana & G. Reed. Academic Press, San Diego, pp. 32146. Mogea, J. (1991). Indonesia: Palm utilization and conservation. In Palm for Human Needs in Asia, eds D. Johnson & A. A. Balkema. Rotterdam, pp. 37-73. Montgomery, D. C. (1984). Experiments to compare several treatments: The analysis of variance. In Design and Analysis of Experiments. John Wiley & Sons, New York, pp. 43-107. Nikolov, Z. L., Meagher, M. M. & Reilly, P. J. (1989). Kinetics, equilibria, and modeling of the formation of oligosacD-ghCOSe with Aspergillus niger charides from glucoamylases I and II. Biotechnol. Bioeng., 34, 694-704. Pontoh, J. & Low, N. H. (1995). Selected chemical, physical and physicochemical properties of six Indonesian palm starches. Starch/Staerke (in press). Rastall, R. A., Adlard, M. W. & Bucke, C. (1991). Synthesis of heterooligosaccharides by glucoamylase in reverse. Biotechnol. Lett., 13, 5014. Reeve, A. (1992). Starch hydrolysis: process and equipment. In Starch Hydrolysis Products. Worldwide Technology, Production, and Applications, eds F. W. Schenck & R. E. Hebeda. VCH, New York, pp. 799120. Takeda, Y., Takeda, C., Suzuki, A. & Hizukuri, S. (1989). Structures and properties of sago starches with low and high viscosities on amylography. J. Food Sci., 54, 177-82. White, J. S. (1992). Fructose syrup: production, properties and applications. In Starch Hydrolysis Products: Worldwide Technology, Production, and Applications, eds F. W. Schenck & R. E. Hebeda. VCH, New York, pp. 177-99. (Received
8 July 1994; accepted
8 October
1994)
Printed in Great Britain. All rights reserved 0963-9969195$9.50 + .OO
ELSEVIER 0963-9969(95)00010-O
Glucose syrup production from Indonesian palm and cassava starch Julius Pontoh & Nicholas H. Low* Department of Applied Microbiology and Food Science, University of Saskatchewan, Saskatoon, SK, Canada S7N 0 WO
Six palm starch samples and one cassava starch sample from Indonesia were converted into glucose syrup with comparison to a commercial corn starch, sample. The conversion was carried out by both liquefaction using a-amylase from B. stearothermophilius and saccharification using glucoamylase from A. niger. The liquefaction time for Metroxylon starch samples was longer than that observed for the other starch samples. Viscosity during liquefaction for palm and cassava starch samples showed the same variation. Based on dextrose equivalent (DE) and high performance liquid chromatography (HPLC) results, starch conversion to glucose for five of the palm and the cassava starch sample was equivalent to that observed for the corn starch sample. Starch conversion to isomaltose and maltose for the palm and cassava starch samples was equivalent to that for the corn starch sample. In general, starch conversion to higher oligosaccharides (DP-3 to DP-7) for the palm and cassava starch samples was higher than that observed for the corn starch sample. Therefore, based on the liquefaction time, percent conversion to glucose and total oligosaccharides, all palm and cassava starch samples, except for one A. pinnata starch sample, could be used for glucose syrup production. Keywords: glucose syrup, caloric sweetener, starch, corn, cassava, palrnkago,
(Y-
amylase, glucoamylase, enzymic process.
Sulawesi, and sugar palm is plentiful in all regions of South East Asia (Mogea, 1991). It has been reported that sago starch could be used as raw material for glucose syrup production (Arbakariya et al., 1990; Govindasamy et al., 1992), however, detailed results have not been reported for this conversion. The purpose of this research was to study the conversion of six palm and one cassava starch sample from Indonesia into glucose syrup with corn starch as a standard.
INTRODUCTION World high fructose syrup (HFS) consumption has been continually increasing due to its extensive use in beverages and processed foods (White, 1992). HFS is produced by the hydrolysis of starch into glucose followed by isomerization into fructose. Therefore, glucose syrup which is also referred to as dextrose syrup, is an intermediate in HFS production. In general, corn starch is the main raw material for glucose syrup production, however, in Indonesia, cassava starch is most often used (White, 1992). Several palm starches traditionally used as staple foods in South East Asia are potential raw materials for glucose syrup production. These include: sugar palm (Arenga pinnata Merr), aren sagu (A. microcarpa Becc.) and sago palm (Metroxylon sagu Roettboell; h4. rumphii Mart.) (Mogea, 1991). There are approximately one million hectares of sago palm forest in Indonesia (Flach, 1983). Aren sagu is abundant in North *To whom correspondence
MATERIALS
AND METHOD
Materials Two sago (M. rumphii, I and II) starch samples and one ‘aren sagu’ (A. microcarpa) starch sample were obtained from starch processors in Manado, Indonesia. One sag0 (M. sagu), one sugar palm (A. pirmata, II) and one cassava starch sample were obtained from a small commercial plant in Bogor, Indonesia. One sugar
should be addressed. 379
380
J. Pontoh, N. H. Low
palm (A. pinnata, I) starch sample was processed by J. Pontoh employing traditional processing methods. Complete starch sample preparations are described elsewhere (Pontoh & Low, 1995). A commercial corn starch sample was purchased locally (Best Foods Canada Inc.). a-Amylase for liquefaction was supplied by Enzyme Bio-Systems Ltd., (Englewood Cliffs, NJ, USA; G-ZYME G 995; produced by Bacillus stearothermophilus) with an activity of 4100 units/g (specific gravity: 1.15-1.20 g/ml). Glucoamylase for saccharification was also supplied by Enzyme BioSystems Ltd, (G-ZYME G 990; produced by Aspergillus niger) with an activity of 200 units/ml. Unless mentioned, other reagents were analytical grade or better. Liquefaction and saccharification Each sample (weight equivalent of 60 g starch) was weighed directly into the 400 ml batch reactor vessel (Figure 1) and HPLC grade water was added to bring the total weight of slurry to 200 g. The resulting slurry was stirred and the pH was adjusted to 5.7 by the addition of either 1N HCl or 1N NaOH. Following stirring of the slurry (~5 min) 35 ~1 of a-amylase was added to the vessel and the resulting slurry was heated to 80°C (oil bath; Ikamag, Rose Scientific, Edmonton, AB, Canada) and maintained at this temperature for 3 min to partially reduce the viscosity. The temperature was then rapidly increased to 106°C (+l’C; the approximate time to reach this temperature was 2 min) and maintained at this temperature for 5 min, and then the temperature was rapidly reduced to 95°C (approximately in 1 min). This temperature was maintained until a final dextrose equivalent (DE) of 12.5-15.0 was reached (30-90 min, depending on the sample). Following liquefaction the resulting syrup was cooled to 60°C by immersing the reactor vessel in ice water. The syrup was adjusted to pH 4.5 by the addition of 1 N HCl and transferred to a 1 1 Wheaton bioreactor (Wheaton Instrument, Millville, NJ, USA) which was maintained at 60°C using a Haake D3-G circulating thermostat (Haake Mess-Technik Co., Berlin, Germany) and 60 ~1 of glucoamylase was added. Samples were continually
stirred using a magnetic stirrer and aliquots were removed at time intervals of 24,48,72 and 96 h for DE and total carbohydrate analysis. Six replicates for corn and four replicates for each palm and cassava starch sample were run. Starch slurry viscosity The effect of a-amylase on starch slurry viscosity was determining using a Brabender viscoamylograph (C.W. Brabender Instruments Inc., South Hackensack, NJ, USA) maintained at 75 rpm. Viscosity was determined on a 30% (w/w) starch slurry with the addition of 87.5 ~1 of a-amylase per 500 ml of slurry. Viscosities were determined using the following viscoamylograph temperature program: constant-preheating at 30°C for 5 min gradient heating from 30 to 95°C for 44 min, and constant heating at 95°C for 30 min. Determination of dextrose equivalent (DE) Samples were analyzed using the Association of Official Analytical Chemists (14th edition, 1984) method 31.035 (Lane-Eynon method). A 0.5 ml sample aliquot was transferred to a 100 ml volumetric flask and made up to volume by the addition of HPLC grade water. Five ml of Fehling A solution (69.278 g CuS04.5H,0 in 1 1 distilled water) and 5 ml of Fehling B solution (346 g KNaC4H,06 and 100 g NaOH in 1 1 HPLC grade water) were added to a 250 ml erlenmeyer flask and 3 drops of 1% (w/v) methylene blue solution was added. The resulting solution was heated and maintained at boiling for 2 min. This solution was then rapidly titrated (< 1 min) with the sample solution until the end point was reached (colorless solution). Total dextrose or glucose calculated as reducing sugar was obtained from the AOAC conversion table and dextrose equivalent was calculated using the following equation: weight of glucose (from the conversion table)
x 100 (1)
weight of dry syrup sample
High performance liquid chromatography (HPLC) analysis
Fig. 1. Diagram of liquefaction apparatus consisting of: bath reactor (a); thermometer (b); pressure valve (c); oil bath (d); and hot plate (e).
Samples were analyzed on a Dionex Bio LC 4000 gradient liquid chromatograph (Dionex, Sunnyvale, CA, USA) with a Dionex 10 pm Carbo Pat PA1 pellicular anion exchange column (4 X 250 mm). A 100 ~1 sample loop was used for analysis and the mobile phase flow rate was 1.0 ml/min. Carbohydrates were detected by a pulsed amperometric detector (PAD; Dionex) with a gold electrode and triple pulsed amperometry at a sensitivity of 10 K. The electrode was maintained at the following potentials and duration: E, = 0.05 V (t, = 120 ms); E2 = 0.80 V (t2 = 120 ms); E3 = -060 V (t3 = 420 ms).
Glucose syrup production from Indonesian palm and cassava starch
Sample preparation involved appropriate dilution with HPLC grade water (glucose: 1 in lo4 ml; oligosaccharides: 1 in 25 ml) followed by passage through a 0.20 pm syringe filter (Corning Glass Works, Corning, NY, USA). A standard curve for glucose was prepared using a series of glucose (BDH, Toronto, ON, Canada) solutions which varied in concentration from 30 to 50 ppm, in 3 ppm increments. Standard curves for oligosaccharides were prepared from a stock oligosaccharide solution which contained 5.0 mg of isomaltose, 5.8 mg of maltose, 7.6 mg of maltotriose, 7.3 mg of maltotetraose, 7.8 mg of maltopentaose, 7.4 mg of maltohexaose and 7.9 mg of maltoheptaose (all from Sigma, St. Louis, MO, USA), respectively, in 50 ml of HPLC grade water. Dilutions ranged from 10 to 50 (v/v basis). Glucose elution was afforded with an isocratic mobile phase of 80 mM NaOH, and the following gradient elution program was used to achieve oligosaccharide separation: 100 mM NaOH for 8 min; from 8 min to 48 min a linear gradient of 250 mM sodium acetate (NaOAc) was used; the column was then regenerated by the immediate addition of 300 mM NaOH (30 min), followed by column reequilibration with 100 mM NaOH (30 min).
381
Table 1. Time required to reach a dextrose equivalent of 12-15 at 95°C (liquefaction time) for starch samples
Liquefaction time (min)
Starch sample Corn0 Cassava”
30 30
Metroxylon rumphii I” Metroxylon rumphii II” Metroxylon sagu” Arenga microcarpa’ Arenga pinnata I” Arenga pinnata II”
60
50 90 30 40
40
‘Based on three determinations.
time of A. microcarpa was similar to that of corn, but all other palm starch liquefaction times were higher. Metroxylon starches had the highest liquefaction times (50-90 min) and Arenga starches the lowest (30-40 min). Reeve (1992) suggested that the presence of an antiamylase in sago starch would slow the liquefaction process. However, molecular architecture of the starch could also have a substantial effect on liquefaction.
Temperature
Experimental
design and statistical
96°C
analysis
Experiments were set up in a randomized block design. Analysis of variance was used in order to examine the effect of starting material (starch) on glucose syrup production. Dunnet test (Montgomery, 1984) was used to compare the differences between glucose syrup produced from corn and those from palm and cassava starch. Four replicates for each of the Indonesian starch samples and six replicates for corn were processed in two groups (blocks). The experimental data (DE and carbohydrate composition of glucose syrup after 72 h saccharification time) was processed using StatView 4.01 (Abacus Concepts, Berkeley, CA, USA) at a 5% significance level.
RESULTS Liquefaction
Time
(minutes)
Temperature 96°C
-r B
AND DISCUSSION time
Liquefaction time, the time required to reach a DE of 12-l 5, for each starch sample is shown in Table 1. The liquefaction time observed for corn starch in this study (30 min) was considerably shorter than that reported by Fullbrook (1984) of 60-90 min (industrial practice). This time difference was most likely due to the increased mixing efficiency of the laboratory scale liquefaction. Liquefaction time for cassava starch was equivalent to corn starch, and the liquefaction times for palm starch varied from 30 to 90 min. The liquefaction
-
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-
A.phm/
-
A.@m!a//
--m-
Corn
--
10
20
30
40
Time
60
60
70
80
(minutes)
Fig. 2. Determination of starch viscosity during liquefaction with a-amylase using a Brabender viscoamylograph with the following temperature program,: constant-preheating at 30°C for 5 min; gradient heating from 30°C to 95°C for 44 min, and constant heating at 95°C for 30 min. (A) h4. rumphii I, M. rumphii II, M. sagu, Corn and Cassava; (B) A. microcarpa, A. pinnata I, A. pinnata II, Corn and Cassava.
J. Pontoh, N. H. Low
382
For, example, it has been reported (Takeda et al., 1989) that the molecular weights of sago starch amylose and amylopectin are 4-7 times higher than that of corn and cassava starch. This increase in molecular weight lengthens the liquefaction time. The significant difference in liquefaction times between M. sagu and M. rumphii might also be due to damaged M. rumphii granules as observed by scanning electron microscopy (SEM; Pontoh & Low, 1995.
-Corn -cassaVa ._ -
-
M.sagu
M.nnphiiI
-
A.mlcmcalp9 A.pinmtaI
M.lw@lllII
-
A.@naall
I 24
Viscosity during liquefaction
49
72
96
Sacchariiication Time (Hours)
Figure 2 shows the viscosity profile of each starch sample under liquefaction conditions. During liquefaction, cassava had the lowest and A. microcarpa the highest viscosity. Compared to corn, three palm starch samples had lower and three higher liquefaction viscosities. Low liquefaction viscosity indicates a greater susceptibility of the granule to enzymic attack. Of the Metroxylon starch samples only M. rumphii I exhibited a lower viscosity than corn. This may have been due to the observed (SEM) extensive granule damage of this starch (Pontoh & Low, 1995). Of the Arenga starch samples only A. pinnata I had a higher liquefaction viscosity than corn. This may have been due to the presence of fragments on the surface of these starch granules (Pontoh & Low, 1995). Therefore, Metroxylon samples have a higher viscosity than corn, whereas, Arenga samples had lower viscosities under these liquefaction conditions. Low viscosity could result in reduced energy consumption during liquefaction. Dextrose equivalent Figure 3 presents the DE values reached during saccharification. Each of the syrups, except cassava, reached its optimum DE value between 48 and 72 h (corn at 72 h). The cassava sample reached its optimum DE in the shortest saccharification time (24 h). The mean DE value obtained for corn was 96.0 (Table 2). This value was slightly lower than that nor-
Fig. 3. Change in dextrose equivalent of syrups during saccharification with glucoamylase at 60°C for each starch sample. mally obtained in industrial practice of 97 to 98 (Reeve, 1992). Results indicated that the DE value obtained for corn was not significantly different (P > 0.05) from those obtained for each of palm starch samples, except for A. pinnata 1. Therefore, each of these samples was equivalent to corn as a raw material for glucose syrup production under these experimental conditions. The DE value obtained for A. pinnata I was significantly lower (P I 0.05) than that obtained for corn. Therefore, A. pinnata I would be a poorer starch source than corn for glucose syrup production.
CARBOHYDRATE ANALYSIS BY HPLC Glucose Percent conversion of starch into glucose for each sample increased during saccharification (Figure 4). The optimum conversion time for each of the palm starch samples in this study ranged from 48 to 72 h. The optimum saccharification time reported by Fullbrook (1984) and Reeve (1992) for industrial glucose syrup production from corn is 48 to 72 h. The mean percent conversion for corn starch at 72 h was 105.5% (Table 2). This value was equivalent to
Table 2. Mean value for dextrose equivalent and percent conversion (g/g) of starch to gh~cose, isomaltose, maltose and alto&se saccharification time of 72 h at 60°C
Starch sample Comb Cassava’ M. rumphiif M. rumphii II’ M. sagu’ A. microcarpaC A. pinnata 1’ A. pinnata II’
Dextrose equivalent
Glucose
Isomaltose
Maltose
Maltotriose
96.0 f 1.9 97.2 + 2.3
10550 f 2.30 105.20f 2.80
1.16 f 0.25 1.60 f 0.10”
1.11 It 0.07 1.40 f 0.06”
0.72 f 0.10 0.87 f 0.06” 1.05 f 0.06”
94.5 AZ1.5
103.50 f 1.9w
1.41 f 0.27
1.40 f 0.15”
94.4 f 1.6
104.70f 1.30
1.28 f 0.10
1.33 f 0.2W
1.03 f 0.04O
95.3 f 1.4 95.6 + 1.1 86.2 f 1.1”
104.50 f 1.30 104.20 f 2.00 94.00 zk3.60”
1.48 f 0.13 1.35 f 0.15 1.21 + 0.06”
1.37 f 0.11” 144fO~ll” 1.48 f 0.21”
95.6 rt 1.1
0.53 f O.OY 1.09 f 0.04” 1.38 f 0.10”
104.60f 1.50
1.33 f 0.05
1.46 f 0.18”
1.10 f 0.07”
“Significantly different from corn at the 5% level. bBased on six determinations. cBased on four determinations.
at a
Glucose syrup production from Indonesian palm and cassava starch
-
24
48
72
96
383
A
96
72
48
24
Saccharification Time (Hours)
Saccharificafion Time (Hours)
Fig. 4. Percent change in starch sample conversion to glucose (g/g) during saccharification with glucoamylase at 60°C.
Fig. 5. Percent change in starch sample conversion to isomaltose (g/g) during saccharification with glucoamylase at 60°C.
96.1% of the total carbohydrate content. This value agreed with industrial starch conversion results of 95-96% (Fullbrook, 1984; Reeve, 1992). Statistical analysis of these results indicates that mean percent starch conversion to glucose for cassava, M. rumphii II, M. sagu, A. microcarpa and A. pinnata II were not significantly different (P > 0.05) at 72 h ofsaccharification when compared to corn (Table 2). Therefore, each of these samples were equivalent to corn with respect to starch conversion to glucose under these experimental conditions. Comparison of A. pinnata I and M. rumphii I values with corn showed that their conversion was significantly lower (P I 0.05) after 72 h of saccharification. However, the DE value of M. rumphii I was not significantly lower (P > 0.05) than that of corn (Table 2).
with respect to isomaltose content. Isomaltose content of cassava was significantly higher (P 5 0.05) than that found for corn. The higher isomaltose content for cassava may have been due to the transglycosylation action of glucoamylase and/or more branching in the cassava starch sample (Nikolov et al., 1989; Rastall et al., 1991).
Oligosaccharides Oligosaccharides are considered to be impurities which require removal to produce a high quality glucose syrup. The major oligosaccharides found in these glucose syrup were isomaltose, maltose and maltotriose. Other oligosaccharides, DP4 (DP = degree of glucose polymerization; i.e. DP-4 = tetraose) to DP-7 were present in low concentrations.
Maltose Figure 6 presents the conversion of starch into maltose during saccharification. Maltose content decreased significantly (P I 0.05) during the first 48 h of saccharification and then became constant. This decrease in concentration was due to the hydrolytic action of glucoamylase. Prolonged saccharification resulted in maltose synthesis via transglycosylation (Nikolov et al., 1989; Rastall et al., 1991) which appeared to offset maltose hydrolysis. The mean percent conversion for corn starch at 72 h this was 1.11% (Table 2). This value was equivalent to 1.01% of the total carbohydrate content. This value was slightly lower than the range reported by Fullbrook (1984) and Reeve (1992) of 1.2-2.0%. Statistical analysis of these results indicates that the six palm samples and cassava sample had a significantly higher (P I 0.05) maltose content than corn starch (Table 2).
Isomaltose Figure 5 presents the conversion of starch into isomaltose during saccharification. Isomaltose content for each starch sample increased during saccharification and this increase was due to the limited action of glucoamylase on branch points and the transglycosylation action of this enzyme. The mean percent conversion for corn starch at 72 h was 1.16% (Table 2). This value was equivalent to 1.05% of the total carbohydrate content. This value agreed with the range reported by Fullbrook (1984) and Reeve (1992) of l&2.0%. Statistical analysis of the mean results indicates that the six palm starch samples were not significantly different (P > 0.05) than corn
I P
2.0
r” 0
1.6
6 ._
/
0.8 1.2
e p”
0.4
--t -cassaVa
Corn
48
-
A.mhcqa M.aagu
-
A.pinnataI
72
Sacchariiication Time (Hours)
Fig. 6. Percent change in starch sample conversion to maltose (g/g) during saccharification with glucoamylase at 60°C.
J. Pontoh, N. H. Low
384
.fj
5 A.pimhlII
-
A.pidl
-
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-
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8 5
-
4
-
3
Apirmcrll
2
1
“.”
I
40
24
Sacchariiication
72
48
24
96
Saccharification
Time (Hours)
7. Percent change in starch sample conversion to maltotriose (g/g) during saccharificationwith glucoamylase at 6O’C.
Fii.
96
72
Time (Hours)
Fig. 8. Percent change in starch sample conversion to total DP-4 to DP-7 (g/g) during saccharification with glucoamylase at 60°C.
Maltotriose
nature of these particular oligosaccharides which would result in slow hydrolysis by glucoamylase (Hebeda, 1993). It is also possible that oligosaccharide hydrolysis (DP-4 to DP-7) is offset by synthesis via transglucosylation (Nikolov et al., 1989). Table 3 presents the percent conversion of starch to DP-4, DP-5, DP-6 and DP-7. Statistical analysis of these results indicates that mean percent starch conversion to DP-4 to DP-6 for corn was lower (P I 0.05) than that obtained for cassava, A4. rumphii and Arenga samples. However, total DP-4 to DP-6 of M. sagu was equivalent to that of corn. Percent conversion to DP-7 for corn was significantly lower than that for M. rumphii and A. pinnata I samples. Therefore, corn and M. sagu would be equivalent raw materials for glucose syrup production with respect to total DP-4 to DP-7 content.
Figure 7 presents the conversion of starch into maltotriose during saccharification. Percent conversion of starch to maltotriose slightly decreased during saccharification (2496 h). Percent conversion for corn starch at 72 h was 0.72% (Table 2). This value was equivalent to 0.65% of the total carbohydrate content. This value agreed with that reported by Reeve (1992) of 04-0.8%. Statistical analysis of these results indicates that mean percent starch conversion to maltotriose for corn was significantly lower (P I 0.05) than that for cassava, M. rumphii, A. microcarpa and A. pinnata samples. However, corn maltotriose content was significantly higher (P I 0.05) than that observed for M. sagu. DP-4 to DP-7 Total DP-4 to DP-7 content for each starch sample decreased significantly (P I 0.05) during the first 48 h of saccharification and then became constant (Figure 8). This decrease in concentration was due to the hydrolytic action of glucoamylase. Prolonged saccharification did not reduce total DP-4 to DP-7 concentration. This could be due to the highly branched
CONCLUSIONS In general, dextrose equivalent data agreed with the conversion of starch to glucose. Based on these results, it can be concluded that all palm and cassava starch samples except A. pinnatu I could be used for glucose
Table 3. Mean value for percent conversion (g/g) of starch to DP-4, DP-5, DP-6 aud DP-7 at a saccharification time of 72 h at 60°C Starch sample corn* Cassava’ M. rurnphif M. rumphii
II’
M. sag& A. microcarpac A. pinnata 1’ A. pinnata II’
DP-4
DP-5
DP-6
DP-7
0.14 f 0.01 0.20 f 0.03”
0.15 AZ 0.01 0.30 * 0.04”
0.18 + 0.01 0.30 f 0.05”
0.19 f 0.01 0.26 f 0.03
0.21 f 0.01”
0.32 + 0.04”
0.29 f 0.02’
0.34 f 0.03”
0.20 f 0.00” 0.13 f 0.00
0.36 f 0.02” 0.14 + 0.03
0.30 + 0.02” 0.21 f 0.02
0.34 + 0.03” 0.27 f 0.01
0.23 + 0.02”
0.30 * 0.02”
0.27 f 0.02”
0.32 f 0.03”
0.30 + 0.01”
0.54 f 0.03”
0.42 f 0.05”
0.48 f 0.08
0.23 f 0.02”
0.38 + 0.03”
0.31 f 0.01”
0.32 f 0.03
“Significantly different from corn at the 5% level. *Based on six determinations. ‘Based on four determinations.
Glucose syrup production from Indonesian palm and cassava starch syrup production. Under these liquefaction conditions, Metroxylon samples showed higher viscosity which may translate to higher energy input, whereas, Arenga samples showed lower viscosity. The liquefaction time for Metroxylon samples were also longer than that observed for corn. Palm and cassava glucose syrup had slightly higher oligosaccharide contents than corn that may require purification. Therefore, some minor modifications in commercial glucose syrup production for Indonesian palm starch may be required.
REFERENCES Arbakariya, A., B. Ali-Asbi & R. Norjehan (1990). Rheological behavior of sago starch during liquefaction and saccharification. In Enzyme Engineering 10, eds H. Okada, A. Tanaka & W. Blanch. Annals of the New York Academy of Sciences, Vol. 613, New York, pp. 610-13. Flach, M. (1983). The Saga Palm. FAO Plant Production and Protection, Rome, Paper 47. Fullbrook, P. D. (1984). The enzymic production of glucose syrups. In Glucose Syrups: Science and Technology, eds S. Z. Dziedzic & M. W. Kearsley. Elsevier Applied Science, London, pp. 65-115. Govindasamy, S., Oates, C. G. & Wong, H. A. (1992). Characterization of changes of sago starch components during hydrolysis by a thermostable alpha-amylase. Carbohydrate Polymers, 18, 89-100.
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Hebeda, R. E. (1993). Starches, sugar and syrups. In Enzymes in Food Processing, eds T. Nagodawithana & G. Reed. Academic Press, San Diego, pp. 32146. Mogea, J. (1991). Indonesia: Palm utilization and conservation. In Palm for Human Needs in Asia, eds D. Johnson & A. A. Balkema. Rotterdam, pp. 37-73. Montgomery, D. C. (1984). Experiments to compare several treatments: The analysis of variance. In Design and Analysis of Experiments. John Wiley & Sons, New York, pp. 43-107. Nikolov, Z. L., Meagher, M. M. & Reilly, P. J. (1989). Kinetics, equilibria, and modeling of the formation of oligosacD-ghCOSe with Aspergillus niger charides from glucoamylases I and II. Biotechnol. Bioeng., 34, 694-704. Pontoh, J. & Low, N. H. (1995). Selected chemical, physical and physicochemical properties of six Indonesian palm starches. Starch/Staerke (in press). Rastall, R. A., Adlard, M. W. & Bucke, C. (1991). Synthesis of heterooligosaccharides by glucoamylase in reverse. Biotechnol. Lett., 13, 5014. Reeve, A. (1992). Starch hydrolysis: process and equipment. In Starch Hydrolysis Products. Worldwide Technology, Production, and Applications, eds F. W. Schenck & R. E. Hebeda. VCH, New York, pp. 799120. Takeda, Y., Takeda, C., Suzuki, A. & Hizukuri, S. (1989). Structures and properties of sago starches with low and high viscosities on amylography. J. Food Sci., 54, 177-82. White, J. S. (1992). Fructose syrup: production, properties and applications. In Starch Hydrolysis Products: Worldwide Technology, Production, and Applications, eds F. W. Schenck & R. E. Hebeda. VCH, New York, pp. 177-99. (Received
8 July 1994; accepted
8 October
1994)