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Th3_Development of an improved parboiling technology for small to medium-scale rice processors in sub-Saharan Africa
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Th3_Development of an improved parboiling technology for small to medium-scale rice processors in sub-Saharan Africa


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3rd Africa Rice Congress …

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

Published in: Technology, Business

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  • 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,
  • 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.