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American Journal of  Smart 
Technology and Solutions (AJSTS)

Investigation into Optimal Conditions for Enzymatic Hydrolysis of  Cassava Starch to 
Glucose by Amylase from Rice

Olosunde Adebisi William1*, Onumadu Kelechi Selina1, Antia Okon Orua1 

Volume 2 Issue 2, Year 2023
ISSN: 2837-0295 (Online)

DOI: https://doi.org/10.54536/ajsts.v2i2.1763
https://journals.e-palli.com/home/index.php/ajsts

Article Information ABSTRACT

Received: June 18, 2023

Accepted: July 23, 2023

Published: July 30, 2023

The challenge of  finding locally available materials in abundance to meet up with the increase 
in demand for glucose syrup necessitated this study. Enzymatic hydrolysis of  cassava starch 
to glucose using glucose amylase sourced from rice was conducted. A-3 factor with 6 levels 
factorial viz. substrate concentration (0.5, 1.0, 1.5, 2.0, 2.5 and 3.0% w/v), pH (4, 5, 6, 7, 8 
and 9) and temperature (30, 40, 50, 60, 70 and 80 °C) experiment were employed. Rice malt 
was prepared and enzyme activated. Starch (substrate), buffer solutions, standard glucose 
solution and its calibration curve were also prepared. Starch was hydrolyzed by α-amylase 
and tested for presence of  reducing sugar using Benedict solution. Time course of  the 
reaction was studied and enzyme activity determined. It was observed that as reaction 
time increased (t), amount of  glucose produced [P] initially increased but soon recorded 
infinitesimal increase and later assumed constant. The effects of  substrate concentration, 
pH and temperature were found to be essential on glucose production. Statistical analysis 
on the effect of  substrate concentration [S], reaction time and their interactions showed 
significant impact at probability level of  (p) = 0.05.

Keywords
Amylase, Cassava, Glucose, 
Hydrolysis, Rice

1 Department of  Agricultural and Food Engineering, Faculty of  Engineering, University of  Uyo, Uyo, P. M. B. 1017, Akwa Ibom
  State, Nigeria
* Corresponding author’s e-mail: williamolosunde@uniuyo.edu.ng

INTRODUCTION
Unmodified starches have diverse functional properties 
depending on the source of  the crop. Several starch 
products may be made from these unmodified starches 
which are regarded as primary resources. The native 
starch has restricted applications. This is because it has 
high predisposition to high syneresis, retrogradation, risky 
processing factors such as temperature, pH, etc (Omojola 
et al., 2011). The modification of  native starch may go a 
long way in curbing the limitations. This could be attained 
through esterification, etherification, enzymatic or acid 
hydrolysis, cross linking and grafting of  starch. Starches 
possess permeable surfaces. Cassava starch has smooth 
surfaces which are difficult to degrade than those of  corn 
starch (Franco et al., 1988; Jane, 2006). Starch structures 
are composed of  two linkages: α-(1-4) and α-(1-6) linkages. 
Hydrolysis of  starch involves the process of  digestion in 
which enzyme hydrolysis in the digestion system break 
down the polymer to individual basic glucose units. 
Various industries extensively use starch hydrolysis in the 
production of  several bio products. Many low molecular 
mass products such as sugar, brewing, spirits and textile 
are made by some food processing and other industries 
from starch. Starch hydrolysis is presently carried out 
using acid and enzymatic hydrolyses (Adenise et al., 2002; 
Odebunmo and Owalude, 2005). Milder conditions such 
as normal pressure, lower temperature (up to 10 0C), and 
medium pH of  6 to 8 are used for enzymatic hydrolysis 
(Kolusheva and Marinova, 2007). Enzymatic hydrolysis 
is considered to have a high reaction rate in terms of  its 
potency to denature detergents, solvents and proteolythic 
enzymes; and lower reaction medium viscosity at higher 
temperatures, etc. It is often done using α-amylase which 
may be got from diverse sources, while β-amylase is rarely 

employed (Eric, 2017). The source, in which the inner 
part of  its chain composed of  polysaccharide molecules, 
is always attacked by bacterial α-amylase enzymes. The 
destruction of  spiral polysaccharide chain which produces 
3 to 10 units of  sugar is aided by the action of  starch 
amylose which leads to the disappearance of  a typical 
blue colour when stained with iodine (Pontoh and Low, 
1995). For the purpose of  hydrolysis of  starch to glucose, 
various grains and cereals like rice, maize, sorghum and 
wheat could be used as enzyme sources. Recent report 
from the Western Press has that this simple technology 
currently being used for making simple sugars from 
cassava starch (Tello et al., 1993). A study by Hammond 
and Ayernor (2000) gave maximum yield of  sugars when 
starches obtained from various types of  cereal malts were 
hydrolyzed. Many factors such as size of  granules, source 
of  starch, crystallinity, starch components extension 
of  association, amylase and amylopectin reaction rates, 
type of  polymorphism (A, B and C), enzyme type, 
complex of  amylose lipid, and conditions of  hydrolysis 
(concentrations, pH and temperature) may contribute 
to variations in the enzymatic vulnerabilities of  starches 
(Hoover and Zhou, 2003; Li, 2004; Tester et al., 2006). 
Simple enzymatic reactions must take into account the 
factors which may affect the rate of  reactions. These 
factors include pH, temperature, concentration of  
reactant, enzyme concentration, inhabitation by products, 
etc (WCB, 2020). Enzyme deactivation cannot be over 
looked on either kinetic studies or reactor engineering. 
In Nigeria, because of  high exchange rate of  naira 
currency to dollar it is difficult to meet the importation 
of  certain raw materials such as enzyme (gluco amylase). 
Therefore, there is need to carry out more researches 
on the use of  rice seedlings as source of  amylase to 



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hydrolyze starch for glucose production (Bailey and 
Ollis, 1986; Onyenekwe, 2013). 
The choice of  cassava (Manihot esculenta Crantz) as a 
substrate source in this study is its abundance in Nigeria 
(Adejumo and Ola, 2010; Balagopalan, 2002; Osipina 
and Wheatley, 2005). Due to the increase in demand for 
glucose syrup and high cost of  importing them, there is 
need to fully utilize and diversify cassava crop. More so, 
cassava and rice are viewed as rich sources of  sugar and 
hydrolytic enzyme (gluco amylase) respectively; may be 
utilized as raw materials in the production of  glucose as 
well as other industrial productions. 

METHODS
Reagents and Equipment
The chemicals used were analytical grade from Merck, 
England; BDH, England and Sigma, USA. The equipment 
employed was spectrophotometer.

Sourcing of  Cassava and Rice Paddy
Cassava (Manihot esculenta) roots, TMS 30572 tubers 
were purchased at Research Institute, Umudike, Abia 
State while rice paddy was sourced at Afikpo, Ebonyi 
State. 

Preparation of  Rice Malt, Enzyme Activation and 
Buffer Solutions
The rice paddy was soaked in water, drained and kept 
inside a container for 2 days (48 hours). It was spread 
on shallow bed (ridge) and allowed to germinate in the 
dark. Wet rice malt was harvested, cleaned, sun dried; and 
ground into high diastatic powder (Onyenekwe, 2013). 2g 
of  the powder was suspended in 100 ml of  distilled water 
at 600C for ten (10) minutes to activate enzyme amylase 
in the powder.  The supernatant was discarded leaving the 
cells in the solution (Onyenekwe, 2013). 
The following buffer solutions were prepared using 
mixing adjusters and salt solutions coupled with addition 
of  distilled water to make up to 200 ml (AnalChem-
Resources, 2023):
pH 4: 0.1 M potassium hydrogen phthalate (100 ml) + 0.1 
M HCl (0.2 ml) 
pH 5: 0.1 M potassium hydrogen phthalate (100 ml) + 0.1 
M NaOH (45.2 ml)
pH 6: 0.1 M potassium hydrogen phosphate (KH2P04) 
[100 ml] + 0.1 M NaOH (11.2 ml)
pH 7: 0.1 M potassium hydrogen phosphate (KH2P04) 
[100 ml] + 0.1M NaOH (58.2 ml) 
pH 8: 0.1 M tris aminomethane (100 ml) + 0.1 M HCl 
(58.4 ml) 
pH 9: 0.1 M tris aminomethane (100 ml) + 0.1 M HCl 
(11.4 ml)

Preparation of  Starch, Substrate and Standard Curve 
of  Glucose D Concentration
Cassava roots (30 kg) were peeled, washed in water and 
grated with a commercial grater. The pulp was screened 
using 25 mm aperture mesh and later suspended in water. 

The supernatant was decanted after allowing the pulp 
to sediment for about 6 hours. The white starch cake 
was obtained and sun dried for about 72 hours (3 days) 
(Oyewole and Obieze, 1995). 
Cassava starch concentrations of  0.5 intervals were 
prepared up to 3.0% (w/v) using each buffer solution 
obtained in Section 2.3. Each starch (substrate) 
concentration was gelatinized in water bath at 80 °C for 
10 minutes (Nam, 2023).
A stock solution of  0.1% (w/v) was prepared by 
dissolving 1.0 g of  glucose D in 1000 ml of  distilled 
water. The stock solution was then used to prepare 
glucose concentration of  50 ppm interval up to 300 ppm 
(Rebecca et al., 2016). For each glucose concentration, 
about 2 ml of  Dinitrosylic acid (DNS) reagent was added 
and then warmed in water bath at 800C for 10 minutes to 
develop colour for spectrophotometer reading. 
A blank solution of  distilled water and DNS was prepared 
and used to calibrate spectrophotometer to be used in 
absorbance readings of  glucose D concentration (Nam, 
2023). The results (spectrophotometer readings) were 
recorded. A standard glucose curve was then produced.

Determination of  Alpha Amylase Activity: Enzyme 
Assay
The activity of  enzyme (rice amylase from malted rice) 
was determined according to Silva et al. (2008). The rice 
enzyme was activated by incubating 3 g of  the enzyme 
(ground malted rice) suspended in 10 ml of  distilled water 
at 50 °C for 10 minutes. The supernatant discarded leaving 
the cells in solution. Enzyme solution (6 ml) was mixed 
with phosphate buffer (4 ml) at pH of  5.0 and 10 ml of  
starch solution 2% (w/v). The mixture was incubated at 
40 °C for 10 minutes. Then, the reaction was discontinued 
after addition of  2 ml of  0.1 M HCl and colour developed 
by adding 0.5 ml iodine reagent. After cooling to room 
temperature, the amount of  glucose produced was found 
by measuring the solution absorbance at 540 nm using 
Spectrophotometer. However, 1.0 mg of  glucose solution 
reacting with coloured reagent produced an absorbance 
of  1.0 under the same condition. One unit of  enzyme 
is referred to as the quantity of  enzyme which produced 
1.0 mg equivalent of  glucose per minute under the assay 
condition (Edu-Enzyme, 2018; Jasco International, 2019).

Assessment of  Glucose Production from Starch 
using Enzymatic Hydrolysis 
Phosphate buffer (0.2 M pH 6.0) was used to disperse 15% 
w/v starch, with bacterial α -amylase solution (0.2% w/v) 
(3 ml). Exactly 1 ml aliquot sodium azide solution (10% 
w/v) was incubated at 37 °C for 48 hours in an orbital 
shaker. The quantity of  reducing sugar was found after 
solids were decanted, and the aliquots of  the supernatant 
removed at 6, 9, 24, 30 and 48 hours. At the expiration 
of  incubation period of  48 hours, the dispersed enzyme 
was deactivated by the addition of  0.1 N HCl to reach 
pH of  3.0. This was followed by 15 minutes stirring. The 
resultant solution was neutralized with 0.1 N NaOH and 



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centrifuged at 2100 rpm for 20 minutes. Distilled water and 
ethanol were used to wash the hydrolyzed residues through 
filtration. The residues were dried using a hot air oven at 
40 °C (Franco and Ciacco, 1992). Thereafter, Benedict test 
for the presence of  reducing sugar was then carried out 
according to AOAC (1998) and Geetha (2012) methods. 

Experimental Design 
The experimental design was three (3) factors (substrate 
concentration, pH and temperature) as variables at 6 
levels as adopted by Khan (2013). The levels selected 
for the glucose production were as follows: substrate 
concentration, Sc (0.5, 1.0, 1.5, 2.0, 2.5 and 3.0% w/v), 
pH (4, 5, 6, 7, 8 and 9) and temperature, tp (30, 40, 50, 60, 
70 and 80° C) (Torreggiani and Bertolo, 2001; Rosa and 
Giroux, 2001; Nieto et al., 2001; Ozen et al., 2002; Jain 
and Verma, 2003). The experiment was done in replicate. 

Experimental Procedure
The optimal values of  the variables for the production of  
glucose were obtained based on the following experiment: 

Effects of  pH on Concentration of  Glucose (Sugar) 
Produced
10 ml of  each of  the six (6) pH level (4, 5, 6, 7, 8 and 9) was 
added separately to six (6) different test tubes containing 
0.5% w/v of  substrate prepared and gelatinized at 80 °C 
and cooled.  They were positioned in water bath at 30 °C.  
About 4 ml of  activated enzyme was then added to each 
of  the six (6) contents of  the test tubes. This was allowed 
to hydrolyze for 10 minutes. About 2 ml aliquot was 
used to prepare enzyme assay which was measured using 
spectrophotometer. Exactly 2 ml DNS reagent was added 
to discontinue the reaction and then heated to develop 
colour. This was cooled in cold water and their various 

absorbance readings with spectrophotometer at 540 nm 
were taken, recorded and tabulated. However, effects of  
pH on concentration of  glucose (sugar) produced was 
evaluated. Statistical analysis analyzed was carried out 
using Analysis of  Variance (ANOVA) at 5% level of  
probability embedded in Statistical Package for Social 
Scientists [SPSS] Version 20.

Effect of  Temperature and Substrate Concentrations 
on Concentration of  Glucose (Sugar) Produced
The process described in Section 2.8 (a) was carried out at 
40, 50, 60, 70 and 80 °C. Also, the substrate concentrations 
of  0.1, 1.5, 2.0, 2.5 and 3.0% (w/v) were used separately. 
Their absorbance’s readings were recorded and tabulated.

Evaluation of  Optimal Parameters Required to 
Produce Glucose during Hydrolysis
The optimal parameters (pH, temperature and substrate 
concentration) were found based on the optimum 
concentration of  sugar obtained. 

Time Course of  Reaction to Produce Glucose
The optimal parameters were then used to study 
the time course of  the reaction to produce glucose. 
Spectrophotometer reading before and after dilution, and 
the corresponding mean amount of  glucose produced 
after conversion were noted.  These data were used to 
plot several curves of  glucose concentrations produced 
against reaction times.

RESULTS
Standard Glucose Calibration Curve and Test for 
Presence of  Reducing Sugar
The plot of  spectrophotometer reading against glucose 
concentration is presented in Figure 1.

Figure 1: Standard glucose calibration curve.

The data for standard glucose calibration curve gave 
Equation 1.
Y = (-4.0 ×10-11.  G4) + (1 ×10-8.G3) + (4 ×10-6. G2) + 
(0.0004 × G) + 0.0021                              (1)  
Where, 1 ppm = 1 mg.L-1 = 0.001 g.L-1, G = glucose 

concentration (ppm) as independent variable and Y = 
diluted value of  spectrophotometer reading (nm) as 
dependent variable. The plot of  spectrophotometer 
reading (nm) against glucose concentration is seen 
to be a polynomial function. From Figure 1, as the 



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spectrophotometer reading increased, the glucose 
concentration also increased which is an indication 
of  a strong direct relationship with coefficient of  
determination (R2) of  0.9955. Similar trend was reported 
by Sciencell (2019), Megazyme (2019) and Tunde (2020) 
with R2 of  0.9962, 0.9990 and 0.9889, respectively.
The α-amylase was found to hydrolyze the starch by giving 
a brick red colouration when applying Benedict test. This 
was an indication of  the presence of  glucose obtained. 
Similar studies were conducted by UkEassys (2018) and 
Cochran et al. (2008), and they also had the same result 
from the hydrolysis of  starch using amylase enzyme.

Effect of  pH, Temperature, and Substrate 
Concentrations on Glucose Concentration Produced 
for 10 Minutes of  Reaction Time
The effect of  pH, temperature and substrate 
concentrations on concentration of  glucose produced 
was studied for 10 minutes of  reaction time. Based on 
the data generated, the plots of  glucose concentration 
against temperature at various pH values and substrate 
concentrations are presented in Figures 2 to 5, while 
that of  glucose concentrate produced against pH values 
at various temperatures and substrate concentration are 
shown from Figures 6 to 9.

Figure 2: Plot of  glucose conc. produced against temperature at various pH and constant substrate concentration of  
0.5 %w/v.

Figure 3: Plot of  glucose conc. produced against temperature at various pH and constant substrate concentration of  
2.0 %w/v.

Figure 4: Plot of  glucose conc. produced against temperature at various pH and constant substrate concentration of  
2.5 %w/v.



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Figure 5:Plot of  glucose conc. produced against temperature at various pH and constant substrate concentration of  
3.0 %w/v.

Figure 6: Plot of  glucose conc. produced against pH at various temperatures and constant substrate concentration 
of  0.5 %w/v.

Figure 7: Plot of  glucose conc. produced against   pH at various temperatures and constant substrate concentration 
of  2.0 %w/v.

Figure 8: Plot of  glucose conc. produced against pH at various temperatures and constant substrate concentration 
of  2.5 %w/v.



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From Figures 2 to 9, the minimum glucose concentration 
produced (0.029 g DE. L-1) was recorded when pH of  
9, temperature of  800C and substrate concentration of  
0.5% (w/v) were used, whereas the maximum glucose 
concentration (0.261 g DE. L-1) was obtained, when pH 
of  5, temperature of  400C and substrate concentration 
of  0.5% (w/v) were used. Generally, lower pH favoured 
the higher amount of  glucose produced while high pH 
values produced lesser amount of  glucose. Increases in 
temperature, decreased the concentration of  glucose 
produced. This implies that too high acidic or alkaline 
medium does not favour the activities of  enzymes. 
However, different kinds of  enzymes have specific range 
of  conditions   necessary for their optimal performances. 
At higher temperature, some enzymes might be 

denatured as they are made up of  protein.  Hence, pH 
of  5, temperature of  400C and substrate concentration 
of  0.5% (w/v) were considered as optimum condtions. 
These conditions were used in  studing the time course of  
reaction or simply the production of  glucose with time. 
In a study conducted by UkEssays (2018), the effects 
of  pH (5 to 9) and temperature (300C to 900C) were 
conspicuously  observed on the enzymatic hydrolysis 
of  starch to glucose. Other researchers such as Alias-
Rodinah (2009) and Karolina (2015) also reported the 
effect of  pH, temperature, and substrate and enzyme 
concentrations on the production of  glucose.

Determination of  Enzyme Activity
The outcome of  enzyme activity is presented in Table 1.

Figure 9: Plot of  glucose conc. produced against pH at various temperatures and constant substrate concentration 
of  3.0 %w/v.

Table 1: Activity of  α-amylase from rice in the production of  glucose from cassava starch.
Spectrophotometer 
Reading After Dilution 
[Absorbance] (nm)

Amount of  
Glucose Produced 
(g DE.L-1)

Molar Conc. of  
Glucose Produced (mol 
DE.L-1)

Enzyme Activity

0.349 0.248 0.04468 0.0203 U.L-1 or 0.0203 μ mol.min-1.L

From Table 1, 0.248 g DE.L-1 of  glucose was produced 
when the total volume of  enzyme mix in assay of  22 
ml was incubated for 10 minutes at 400C and pH of  5. 
However, the enzyme activity in this study was found 
to be 0.0203 U.L-1 or 0.0203 μ mol.min-1.L. This means 
0.0203 units of  enzyme catalyzed the transformation 
of  1 μ mol of  substrate into glucose in 1 minute under 
standard conditions. The low value of  the enzyme activity 
might be as a result of  change in optimal pH of  the 
enzyme. This slows down the enzyme activity. However, 
high value might cause enzyme to denature (Cornish- 
Bowden, 1995; Jasco International, 2019).

Production of  Glucose with Time
Time course of  reaction was conducted using 40 0C and 
pH of  5. 
Plots of  several curves of  glucose concentrations 
produced against reaction times is presented in Figure 10.
In Figure 10, initially, the amount of  glucose produced 
at reaction time, t = 0 minute was 0 g DE.L-1. After 10 
minutes, the amount of  glucose produced were 0.150, 

0.190, 0.194, 0.207, 0.207 and 0.227 g DE.L-1 in the six 
test tubes containing substrate concentrations of  0.5, 1.0, 
1.5, 2.0, 2.5 and 3.0 % (w/v) respectively. The production 
within this period increased rapidly. Test tube I with 0.5 
% (w/v) of  substrate concentration showed a gradual 
increase in glucose concentration from 10 minutes to 50 
minutes of  reaction time. Beyond this period, there was 
a decrease in glucose concentration. Test tubes II and III 
with 1.0 and 1.5 % (w/v) of  substrate concentrations, 
also recorded similar increase from 0 to 0.239 and 0.247 g 
DE.L-1 at 50 and 60 minutes, respectively. 
Moreover, test tubes IV and V (contain with substrate 
concentrations of  2.0 and 2.5 % [w/v]), respectively; and 
had almost the same trend. A conspicuous increase in 
the amount of  glucose produced was recorded between 
0 – 20 minutes. This is, an increase from 0.0 to 0.246 
g DE.L-1 for both samples. Test tube VI (with substrate 
concentration of  3.0 % [w/v]) recorded an increase in 
glucose concentration produced from zero to 0.253 g 
DE.L-1 within 40 minutes. Further increase in reaction 
time in both test tubes V and VI did not have any 



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observable increase in the amount of  glucose produced. 
Generally, increase in substrate concentration yielded an 
increase the amount of  glucose concentration produced. 
Virtually, unobservable increase or constant production 
might be due to that the fact the enzyme had reached its 
optimum activity and the substrate had been consumed 
completely. Therefore, maximum glucose concentration 
(0.253 g DE.L-1) produced was found when 2.5% (w/v) 
substrate concentration at 50 minutes reaction time 
or 3.0% (w/v) substrate concentration at 40 minutes 
reaction time was employed.
Similar trends were observed by Cecil (1995) at optimum 
temperature of  500C, where glucose amylase was used 
to hydrolyze cassava starch / paddy rice to maltose. In 
addition, the variations of  glucose concentration with 
time of  reaction in this study were in accordance with 
the works done by many researchers (Cochran et al., 2008; 
Tunde, 2020; Nor, 2009).

Effect of  Substrate Concentration, Reaction Time 
and Substrate Concentration-Reaction Time 
Interaction on Glucose Produced at Constant pH = 
5 and Temperature = 40 0C
The summary of  ANOVA showing the effect of  substrate 

concentration, reaction time and substrate concentration- 
reaction time interaction on glucose concentration 
produced at constant pH = 5 and temperature = 40 0C is 
presented in Table 2.

Table 2: Summary of  ANOVA showing the effect of  
substrate concentration, reaction time and substrate 
concentration-reaction time interaction on the 
glucose produced. 
From Table 2, since p-value [0.00] < 0.05 and coefficient 
of  determination (R2) = 1.00, F value is significant, which 
shows that the substrate concentration and reaction time 
had greater influence on glucose produced. More so, the 
resulting interaction between substrate concentration 
and reaction time had a significant impact on glucose 
produced. In a study conducted by Nor (2009), the 
effects of  liquefaction temperature and saccharification 
pH on glucose production were very significant while 
the saccharification temperature and liquefaction pH, on 
the other hand did not influence the glucose production. 
The observed trend in the present study implies that 
these factors should not be rolled out when considering 
enzymatic hydrolysis of  starch to produce glucose because 
they really influence the amount of  glucose production.

Figure 10: Plot of  glucose concentration produced against reaction time.

Table 2: Summary of  ANOVA showing the effect of  substrate concentration, reaction time and substrate 
concentration-reaction time interaction on the glucose produced
Source of  Variation df F P-value @ 5% Significant?
Substrate concentration 6 3365.130 0.000 Yes
Reaction time 5 74679.197 0.000 Yes
Substrate concentration * reaction time 30 199.227 0.000 Yes

R2 = 1.000

CONCLUSION
Based on the outcome of  the findings, the optimum 
conditions necessary for reasonable glucose production 
(0.253 g DE.L-1 ) were temperature of  40 0C, pH of  5 and 
substrate concentration of  2.5% (w/v) for 50 minutes or 
substrate concentration of  3.0% (w/v) for 40 minutes. 
Alpha-amylase activity was found to be 0.0203 μ mol.
min-1.L. Analysis of  Variance (ANOVA) results on the 
effect of  substrate concentration, reaction time and their 
interaction at 40 0C and pH of  5 on glucose production 
showed a statistically significant impact since Pcal <  Ptab   

at probability level (p) = 0.05.  Furthermore, the use 
of  rice amylase to produce glucose from cassava starch 
would complement increase in demand for glucose syrup 
production. 

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