QUALITY EVALUATION OF MALTOSE SYRUP

PRODUCED FROM HYDROLYSIS OF

CASSAVA STARCH AND MALTED RICE

SREY THEAVY

MSc. In Food Science October 19, 2017

Objectives of the Study

1. determine the proximate composition of fresh cassava and cassava starch;

2. identify the best germination time of paddy rice to obtain the highest amylase production;

3. determine the best processing parameters such as pH, saccharification time, and ratio of substrate (cassava starch) to enzyme (malted rice) for maltose syrup production;

4. evaluate the physicochemical properties [color, pH, % moisture content, total soluble solids (TSS), % reducing sugar, % dextrose equivalent, % crude ash content and % crude protein] and yield (%) of the resulting maltose syrups; and

5. determine the acceptability and sensory properties of maltose syrups from cassava starch.

Experimental Materials

Fig.1. Cassava (Rayong cv.) roots

harvested at the age of 12 month

Fig. 2. Paddy rice (Sen Pidao cv.)

MATERIALS AND METHODS

Experimental Set-up

Table 1. Treatment design for cassava starch hydrolysis using malted rice

at different pH levels

TREATMENTS CASSAVA

STARCH

(g)

MALTED

RICE

(g)

WATER

(mL)

SACCHARIFICATOI

N TIME (hr)

T1 : Cassava Starch : malted rice ratio (200 : 32)

Unadjusted pH 200 16+16 400+800 8

pH 4.0 200 16+16 400+800 8

pH 4.5 200 16+16 400+800 8

pH 5.0 200 16+16 400+800 8

pH 5.5 200 16+16 400+800 8

pH 6.0 200 16+16 400+800 8

pH 6.5 200 16+16 400+800 8

T2 : Cassava Starch : malted rice ratio (200 : 48)

Unadjusted pH 200 24+24 400+800 8

pH 4.0 200 24+24 400+800 8

pH 4.5 200 24+24 400+800 8

pH 5.0 200 24+24 400+800 8

pH 5.5 200 24+24 400+800 8

pH 6.0 200 24+24 400+800 8

pH 6.5 200 24+24 400+800 8

Fig. 3. Protocol of the study

(F) Determine -amylase

activity daily

(E) Germinating of paddy rice in

slanting tray & covering with

black bag for 10 days

Fig 4. Major steps of malted rice production (A)

(G) Seedlings in slanting trays after 8 days

(H) Appearance of seedlings roots

(J) Drying paddy seedling

(Kilning)

(K) Dried paddy seedling

(I) Washing seedlings before use Fig 4. Major steps of malted rice production (B)

Fig. 9. Flow diagram of processing cassava starch (A) Fig . 5. Flow diagram of processing cassava starch (A)

Fig. 9. Flow diagram of processing cassava starch (B) Fig . 5. Flow diagram of processing cassava starch (B)

Fig. 6. Major steps of maltose syrup production (A)

Fig. 6. Major steps of maltose syrup production (B)

Fig. 6. Major steps of maltose syrup production (C)

RESULTS AND DISCUSSION

Table 8. Proximate composition of fresh root and dried starch of Rayong cassava

variety.

COMPOSITION

FRESH CASSAVA ROOT

(%)

DRIED CASSAVA

STARCH

(%)

Starch content 31.00

Moisture Content 53.00 6.10

Crude Ash 2.22 0.00

Crude Protein 1.69 0.31

Crude Fiber 6.43 0.77

Crude Fat 1.20 0.73

Carbohydrate (NFE) 35.46 92.09

Table 2. Proximate composition of fresh root and dried starch of cassava (Rayong cv.)

Laboratory analysis of fresh cassava and cassava starch

0

5

10

15

20

25

30

35

40

45

50

55

60

65

70

0 1 2 3 4 5 6 7 8 9 10

Tem

pe

ratu

re (

oC

)/R

ela

tive

Hu

mid

ity

(%)

Germination period (day)

Temperature (˚C) RH (%)

Fig. 7. Changes in temperature (oC) and relative humidity (%) during germination of rice seeds.

Changes in Temperature and Relative Humidity (RH) of Paddy Rice at Different Germination Period

0

50

100

150

200

250

300

350

400

450

0.00

2.00

4.00

6.00

8.00

10.00

12.00

14.00

0 1 2 3 4 5 6 7 8 9 10

Alp

ha-

amyl

ase

act

ivit

y (U

nit

s/m

L/m

in)

Len

gth

of

sho

ot

& r

oo

t (c

m)

Germination period (day)

Shoot Root a-Amylase activity

Fig. 8. Activity (units/mL/min) of α-amylase in rice seedlings at different germination period (day)

Table 9. Percent reducing sugar (%) and dextrose equivalent (%) of maltose syrup made

from different combination of cassava starch and rice seedlings at different pH

levels.

COMBINATION

OF CASSAVA

STARCH AND

RICE

SEEDLINGS

pH

REDUCING

SUGAR*

(%)

DEXTROSE

EQUIVALENT*

(%)

T1: Cassava

Starch (g) : Rice

Seedlings (g)

(200 : 16+16)

Unadjusted ( pH 5.3) 91.75 ± 0.50b 83.28 ± 2.04

bc

pH 4 82.67 ± 0.38d 79.12 ± 1.88

cd

pH 4.5 68.83 ± 3.19f 64.46 ± 3.01

f

pH 5 87.92 ± 5.35bc

81.36 ± 11.29bc

pH 5.5 87.83 ± 2.89bc

80.38 ± 1.41bc

pH 6 75.58 ± 3.32e 71.29 ± 3.60

e

pH 6.5 87.42 ± 1.38bc

80.21 ± 1.59bc

T2: Cassava

Starch (g) : Rice

Seedlings (g)

(200 : 24+24)

Unadjusted (pH 5.3) 106.83 ± 0.80a 97.07 ± 0.44

a

pH 4 75.75 ± 0.25e 86.61 ± 1.88

b

pH 4.5 66.67 ± 0.63f 64.77 ± 2.85

f

pH 5 88.83 ± 3.76bc

85.76 ± 3.80bc

pH 5.5 89.58 ± 0.14bc

80.71 ± 1.34bc

pH 6 77.33 ± 0.29e 73.16 ± 0.81

de

pH 6.5 86.58 ± 0.14c 80.40 ± 1.54

bc

Values are means ± SD (n=14).

Means in the same column followed by the same superscripts (a–f) are not significantly

different (P < 0.05) by Duncan’s Multiple Range Test;

*Significantly different at P < 0.01; a b c …

Table 3.

Table 10. Physicochemical properties of maltose syrup from different combinations of cassava starch and rice seedling adjusted at

various pH levels.

COMBINATION OF

CASSAVA STARCH AND

RICE SEEDLINGS

pH

pH AFTER 8 HR

SACCHARIFICATION

pH* MOISTURE

CONTENT (%)*

CRUDE ASH

(%)*

TOTAL SOLUBLE

SOLIDS (oBrix)*

T1:Cassava Starch (g) : Rice

Seedlings (g)

(200 : 16+16)

Unadjusted

(pH 5.3) 5.6 5.27 ± 0.06ab 8.97 ± 0.47

d 0.46 ± 0.03

c 76.33 ± 0.58

e

pH 4 4.8 5.03 ± 0.06d 10.09 ± 0.11

c 0.46 ± 0.05

c 76.67 ± 0.58

e

pH 4.5 4.9 4.63 ± 0.06fg

4.65 ± 0.56g 0.43 ± 0.03

c 80.13 ± 0.23

c

pH 5 5.4 5.27 ± 0.06ab

6.20 ± 0.05f 0.45 ± 0.03

c 77.33 ± 1.15

e

pH 5.5 5.5 4.70 ± 0.00ef 8.80 ± 0.05

d 0.48 ± 0.01

c 73.00 ± 1.00

f

pH 6 5.9 4.77 ± 0.06e 11.79 ± 0.17

a 0.63 ± 0.02

a 78.67 ± 0.58

d

pH 6.5 6.2 4.57 ± 0.06gh

7.37 ± 0.22e 0.64 ± 0.03

a 83.67 ± 0.58

a

T2:Cassava Starch (g) : Rice

Seedlings (g)

(200 : 24+24)

Unadjusted

(pH 5.3)

5.2 4.77 ± 0.06e 8.77 ± 0.12

d 0.44

±

0.03c 80.67 ± 1.15

bc

pH 4 4.6 4.53 ± 0.06h 8.93 ± 0.27

d 0.47 ± 0.02

c 80.47 ± 0.50

bc

pH 4.5 4.8 4.57 ± 0.06gh

8.89 ± 0.11d 0.55 ± 0.04

b 78.67 ± 0.58

d

pH 5 5.1 5.20 ± 0.00bc

6.58 ± 0.09f 0.55 ± 0.02

b 83.67 ± 0.58

a

pH 5.5 5.2 5.13 ± 0.06c 6.58 ± 0.24

f 0.58 ± 0.04

b 81.67 ± 0.58

b

pH 6 5.5 5.03 ± 0.06d 10.14 ± 0.09

c 0.66 ± 0.02

a 76.33 ± 0.58

e

pH 6.5 5.7 5.30 ± 0.00a 11.34 ± 0.18

b 0.64 ± 0.05

a 76.33 ± 0.58

e

Mean value is ± SD (n=14). Means in the same column followed by the same superscripts are not significantly different (P < 0.05) by Duncan’s multiple range

test; *Significantly different at P < 0.01; a b c d …

Table 4.

Table 11. Color values of maltose syrups using chromameter.

COMBINATION

OF CASSAVA

STARCH AND

RICE

SEEDLINGS

pH

Val COLOR VALUES

L * a * b *

T1: Cassava

Starch (g) : Rice

Seedlings (g)

(200:16+16)

Unadjusted pH 36.33 ± 1.15ef

16.33 ± 0.06bcd

25.43 ± 1.75d

pH 4 51.60 ± 1.66a 8.63 ± 0.15

j 29.70 ± 0.44

bc

pH 4.5 45.77 ± 2.31b 9.90 ± 0.62

i 30.00 ± 0.60

bc

pH 5 43.97 ± 0.49b 10.90 ± 0.10

h 28.90 ± 0.17

bc

pH 5.5 38.27 ± 2.95de

15.67 ± 0.23de

26.93 ± 3.75cd

pH 6 40.47 ± 2.45cd

15.87 ± 0.67cd

29.33 ± 2.15bc

pH 6.5 33.13 ± 1.86fg

16.83 ± 0.58b 20.30 ± 2.91

e

T2: Cassava

Starch (g) : Rice

Seedlings (g)

(200:24+24)

Unadjusted pH 44.57 ± 1.87b 13.33 ± 0.64

f 31.93 ± 0.71

ab

pH 4 47.07 ± 3.01b 11.87 ± 0.75

g 34.43 ± 1.68

a

pH 4.5 44.60 ± 3.08b 11.90 ± 0.62

g 31.47 ± 2.18

ab

pH 5 43.70 ± 1.44bc

11.87 ± 0.21g 30.63 ± 1.10

b

pH 5.5 30.90 ± 0.44g 18.50 ± 0.30

a 17.70 ± 0.92

ef

pH 6 31.23 ± 0.85g 16.77 ± 0.76

bc 17.13 ± 1.27

f

pH 6.5 30.10 ± 0.52g 14.90 ± 0.79

e 14.70 ± 0.46

f

Mean value ± SD (n=14). Means in the same column followed by the same superscripts are

not significantly different (P < 0.05) by Duncan’s multiple range test;

*Significantly different at P < 0.01; a b c …

Unadjusted pH was 5.3

Table 5.

Fig 10. Maltose syrups from hydrolysis of cassava starch at various amount of malted rice adjusted at different pH levels.

Table 15. Percent yield of maltose syrup from different treatments

COMBINATION OF CASSAVA

STARCH AND RICE

SEEDLINGS

pH YIELD*

(%w/w)

T1: Cassava Starch (g) :

Rice Seedlings (g)

(200 : 16+16)

Unadjusted (pH 5.3) 93.50 ± 2.50de

pH 4 100.50 ± 2.50bc

pH 4.5 98.50 ± 7.26bcd

pH 5 94.00 ± 6.14cde

pH 5.5 92.17 ± 2.52de

pH 6 96.50 ± 1.00bcde

pH 6.5 95.17 ± 4.51cde

T2: Cassava Starch (g) :

Rice Seedlings (g)

(200 : 24+24)

Unadjusted (pH 5.3) 94.50 ± 1.00cde

pH 4 122.33 ± 2.25a

pH 4.5 102.00 ± 4.00b

pH 5 97.50 ± 1.00bcde

pH 5.5 91.00 ± 1.50e

pH 6 96.50 ± 1.00bcde

pH 6.5 97.50 ± 2.00bcde

Mean values ± SD (n=14).

Means in the same column followed by the same superscripts are not significantly different

(P < 0.05) by Duncan’s Multiple Range Test;

*Significantly different at P < 0.01; a b c …

Table 6.

Table 19. Mean score of general acceptability of maltose syrup from cassava starch and

malted rice

COMBINATION OF

CASSAVA STARCH AND

RICE SEEDLINGS pH GENERAL ACCEPTABILITY

Cassava Starch (g) : Rice

Seedlings (g)

(200 : 16+16)

Unadjusted (pH 5.3) 4.79 ± 2.66 ns

pH 4 6.39 ± 2.04 ns

pH 4.5 5.43 ± 2.33 ns

pH 5 5.57 ± 2.08 ns

pH 5.5 5.00 ± 2.48 ns

pH 6 5.07 ± 2.29 ns

pH 6.5 5.11 ± 2.42 ns

Cassava Starch (g) : Rice

Seedlings (g)

(200 : 24+24)

Unadjusted (pH 5.3) 5.21 ± 2.42 ns

pH 4 5.46 ± 2.32 ns

pH 4.5 5.32 ± 2.33 ns

pH 5 5.43 ± 2.28 ns

pH 5.5 6.04 ± 2.15 ns

pH 6 4.82 ± 2.16 ns

pH 6.5 5.82 ± 2.68 ns

Local Product 4.96 ± 2.40

ns

N = 28; Means with the same superscript within the same row are not significant differently

(p 0.05).

Range of scores:

Color: 1 = light brown 8 = dark brown

Viscosity: 1 = too liquid 8 = extremely viscous

Aroma: 1 = no aroma at all 8 = extremely strong aroma

Sweetness: 1 = not sweet at all 8 = extremely sweet

General acceptability 1 = extremely disliked 9 = extremely liked

Table 7.

SUMMARY & CONCLUSION

• Germination time had effect on enzyme production in malted rice. Enzyme activity of malted rice Sen Pidao cv. was high at day 8. Therefore, it is recommended that best germination time for Sen Pidao rice is at day 8.

SUMMARY & CONCLUSION

• Results suggested that T1 without all pH adjustment, pH 5.3 had the highest RS content (91.75 ± 0.50%).

• Likewise, RS of maltose syrup from higher amount of malted rice (T2) also registered significantly higher value in unadjusted pH samples (106.83±0.80%).

• However, samples with higher amount of malted rice obtained significantly higher RS(%).

• The highest values of RS(%) among samples was observed in samples with pH ranged of pH 5-5.5 regardless of the amount of malted rice added in the mixtures.

SUMMARY & CONCLUSION

• Dextrose equivalent of both T1 (83.28 ± 2.04%) and T2 samples (97.07 ± 0.44%) from unadjusted pH obtained the highest values.

• However, there was no clear trend observed on the effect of pH levels on the values obtained for DE.

• Nonetheless, results suggest that pH adjustment within the range of 5.0-5.5 and the use of higher malted rice is necessary to obtain high DE of maltose syrup.

SUMMARY & CONCLUSION

• An 8-hour saccharification period of extracted juice with additional overnight storage resulted in increased pH values for both T1 and T2 before gelationization.

• Overall, it can be concluded that the pH and the proportion of cassava starch to rice seedlings have no substantial effect on the moisture content of the maltose syrup.

• Moisture content of maltose syrups ranged from 4.65 – 11.79% . The final moisture content of the syrup depends on the length of evaporation process.

SUMMARY & CONCLUSION

• Results of crude ash analysis show that regardless of the treatment, samples with pH 6.0 and 6.5 obtained significantly higher crude ash content from the rest of the samples which can be contributed by the amount of NaOH added during pH adjustment.

• In general, maltose syrups from Treatment 1 obtained TSS ranging from 73 ± 1.00oBrix to 83.67 ± 0.58 oBrix, while samples from Treatment 2 had TSS ranging from 76.33 ± 0.58 oBrix to 83.67 ± 0.58 oBrix.

• Results show that the treatments with different pH levels and concentration of rice seedlings did not show any significant effect on the TSS of the final maltose syrups.

SUMMARY & CONCLUSION

• Chromameter, CapSureTM, was used to determine the color of the maltose syrup samples.

• This shows that the more acidic the sample, the lighter is the color. However, varying the amount of malted rice did not affect the color lightness of the products.

• Obviously, the maltose syrup has no tinge of green color hence most of the values obtained refer to the slight redness of the samples.

• The higher the pH value, the higher is the amount of redness detected on the product (dark brown).

SUMMARY & CONCLUSION

• Excessive heating of starch-derived sweeteners will result in partial caramelization and development of undesirable flavors. The b value is for yellow (+) and blue (−) color.

• The values obtained signified that maltose syrup has slight yellow color and not on the blue color side.

• Visual observations of the maltose syrups show less yellow color intensity at low pH values.

• The higher is the b-value, the more intense is the yellow color of the syrup.

• Maltose syrups from T2 show that as the pH values increased, the color of the samples became darker.

SUMMARY & CONCLUSION

• The yield of maltose syrup from both treatments 1 and 2 adjusted to pH 4 obtained significantly higher yield than with unadjusted pH.

• However, samples from T2 exhibited higher yield than T1.

• This loss or reduction in the amount of the filtrate is possibly due to evaporation of moisture during boiling of the mixture before extraction and also on the efficiency of juice filtration.

RECOMMENDATIONS

• The processing parameters for maltose syrup production such as germination time of rice seedling for malted rice production, time for maximum α- amylase production, and the right proportion of cassava starch to malted rice were determined.

• However, there are still areas of research that needs further investigation in order to be competitive in the existing commercial products such as:

RECOMMENDATIONS

• Optimize all other processing parameters for production of consistent quality products using the Response Surface Methodology;

• Use of microbial enzymes for cassava starch hydrolysis;

• Determine the storage shelf life of the most acceptable treatment;

• Develop packaging design of the product;

RECOMMENDATIONS

• Conduct market study to determine the acceptability of the product by the target clients; and

• Determine the production cost or profitability of the maltose syrup in comparison to the existing similar products in the market.