3rd Africa Rice Congress Theme 3: Rice processing and marketing Mini symposium: improving rice processing technologies in Africa Author: Ndindeng, et. al.

1. Development of an improved parboiling
technology for small to medium-scale rice
processors in sub-Saharan Africa
S.A. Ndindeng*, J.T. Manful, N. Woin et al,
S.Ndindeng@cgiar.org

2. The problem with rice in SSA is not
only the quantity but also the quality
• Rice is fast becoming a global staple and its demand is on the
rise especially in Sub Saharan African (SSA) countries.
• The quantity produced is far smaller than what is consumed
• Also the quality of locally produced rice does not satisfy the
needs of urban consumers
• Postharvest losses (quantitative and qualitative) in rice in
most SAA countries has been attributed to poor postharvest
practices and utilization of inappropriate equipment.
• postharvest losses reduction leads to 15–20% increase in rice

3. Proper parboiling can upgrade the
quality of locally produced rice
• Locally produced rice has a high proportion of broken fractions, is of mixed
varieties and contains impurities.
• Proper parboiling reduce grain breakages, impurities and improves on the
nutritional quality of milled rice.
Parboiling is common in SSA countries like
Cameroon, Nigeria, Ghana and Benin but
the parboiling procedure and vessel used
does not consistently result in high quality
parboiled milled rice.
In addition the stove results in high energy
loss and exposes the processors to heat
burns.
Traditional parboiling

4. Methodology
• Constructed a parboiling vessel and stove in
partnership with Taless-Seimef and MIPROMALO
respectively for small to medium scale (10 - 1000 kg
per day).
• Determined the optimum soaking
temperature, steaming time, drying and milling
conditions.
• Compared the outputs of the improved technology
(quality of rice produced and energy efficiency) to
that of the traditional technology.

5. Parboiling vessel and stove
Parboiling Stove
(Reduction of heat loss)
Parboiling Vessel
Uniform distribution of steam

6. Main ideas behind the Parboiling
Technology developed
Two Drying Phases
1st phase, dry to 18 % MC under the sun
2nd phase, dry to 14 % MC under the
shade
Stove uses
- Wood or
- Charcoal or
- Briquettes.
Parboiling Vessel & Stove
Rubber roll or higher
type mills

7. Soaking, Steaming, Drying and Milling are
critical in producing quality parboiled rice
Variety
Husk Type Soaking Temp
(oC)
Steaming Time (Min)
TOX3145
Thin
80
20
CICA-8
Thick
90
25
TIANAN-5
Thick
90
25
Variety
Drying Phases
1st to 18
%MC/2nd to 14
% MC
Shade/Sun
Sun/Sun
Sun/Shade
% Head Rice
% Rotten grains
47.21
71.47
85.00
0.50
0.02
0.05
TOX3145
TOX3145
TOX3145

8. Observed differences in Physical and
Cooking characteristics
Rice type
Non
parboiled
(%) HR
33.46c*
Traditional 55.16b
parboiled
Improved
parboiled
87.71a
CG
HDG(%) Whiteness Yellowness pH Swelling
(No./50gr
(CIE L*)
(CIE b*)
ratio
ains)
6.33b
/
85.52a
11.33b
6.22b 3.26b
11.33a
4.38a
57.63c
16.73a
5.78a
3.16b
1.33c
0.02b
71.39b
11.49b
6.23b 3.53a
HR=Head rice, CG=Cracked grains, HDG= Heat damaged grains
* numbers with different superscript letters are significantly different at the 0.05 level

9. Efficiency of Parboiling Stoves using
The Water Boiling Test
stove
Phases
TTB(mi
n)
BR
(g/min)
SFC
(g/l)
Fire Power
(watts)
TDR
Traditional Cold-start 15.06a*
high power
Improved
10.06b
78.53b
487.47b
23889.43b
/
208.46a
884.47a
63723.60a
/
Traditional Hot-start
14.10a
high power
Improved
8.06b
204.56b
1119.50a
62532.50b
/
259.96a
884.47b
79653.50a
/
Traditional Simmering
/
41.50b
18451.80a
12584.50b
1.90b
Improved
/
92.60a
16746.33b
28187.46a
2.24a
TTB=Time to boil, BR=Burning rate, SFC= Specific fuel consumption, TDR=Turndown ratio
* Numbers with superscript a are higher and different from b at the 0.05 level

10. Quality dedifferentiation of domestic
from imported rice through proper
parboiling
Traditional parboiling
Improved parboiling
 16% of consumer think it was imported &
- Discounted traditionally parboiled rice
by 2%.
63% of consumer think it was imported &
- Paid 5% premium price for improved
parboiled rice.

11. Conclusions & Recommendations
• The improved parboiling technology produced high
quality rice that mimics premium quality imported rice.
• Consumers were willing to pay 5 % premium price for
this rice.
• The stove was more energy efficient and friendly to use
than the traditional stove.
• The technology is easy to build at the village level and
may be easily adopted by small to medium-scale rice
processors in SSA.