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Th3_Evolution et perspectives de la transformation du riz à l’Office du Niger au Mali
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Th3_Evolution et perspectives de la transformation du riz à l’Office du Niger au Mali


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3rd Africa Rice Congress …

3rd Africa Rice Congress
Theme 3: Rice processing and marketing
Mini symposium: constraints to and opportunities for rice processing and marketing
Author: Coulibaly

Published in: Technology, Business

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  • Although Malaysian workers observed 11.7% of paddy left on straws after threshing and 1.13% lost by falling outside the threshing box, nevertheless research findings in this study reported otherwise.
    Farmers who now use mechanised threshing have cut down on their loss margins by 11.84% which is significant
  • Transcript

    • 2. Introduction Why and what was studied ? • Assessing postharvest losses of foodgrains is an important exercise in helping to improve intervention programs aimed at increasing farmer’s productivity. • CIDA-AfricaRice Project- help farmers in Afife to buy into the interventions to be introduced • Quantitative and qualitative postharvest losses in key unit operations(harvesting, threshing, winnowing and drying) occurring the rice value chain at Afife; an irrigated rice farming community in the Volta Region were investigated. Fig. 1: Map of Ghana: Showing Study Area Afife Afife
    • 3. Main Studies • Study 1: Assessment of famers’ perception and knowledge of the causative factors of and solutions for rice postharvest loss. • Study 2: Assessment of the quantitative losses during key unit operations-harvesting, threshing, drying, winnowing and milling. • Study 3: Assessment of the effect of harvesting time on the qualitative losses during these unit operations for the main rice variety at Afife (Togo Marshall).
    • 4. Study 1: Summary of causes of losses perceived by 125 respondents ( 80 males and 45 females) Causes of post harvest loss Storage pests Frequency (%) 5 (4) Bad road network 1 (0.8) Late harvesting 1 (0.8) Field getting waterlogged or flooded during harvesting times . Poor harvesting by hired labourers 4 (3.2%) Manual method of threshing is inefficient 10 (8%) Spillage during winnowing 4 (3.28%) Lack of better storage facilities 2 (1.6%) 25 (20%)
    • 5. Causes of post harvest loss Freq (%) Rains during harvest times 1 (0.8%) Shattering of over-dried rice 3 (2.4%) Improperly threshed straws 6 (4.8%) Inappropriate tarpaulin size for threshing 5 (4 %) Inefficient harvesting method 11(9.02%) Lodging 1 (0.8%) Delays during threshing 6 (4.8%) Spillage during threshing 18 (14.7%) Labour-intensive threshing 2 (1.6%)
    • 6. Study 1: Summary of solutions perceived by respondents for each unit operation. Stage Solutions to rice post harvest losses Harvesting Mechanisation Early harvesting Threshing Mechanisation Early threshing Drying Early drying Use of solar driers Provision of well spaced drying floors Ensure that rice is thoroughly dried Storage Provision of better storage infrastructure such as use of silos Fumigation of storage space Immediate marketing Regular cleaning of storage place Chemical treatment of rice before storage Application of rodenticides
    • 7. Study 2- references of methods used • Harvesting loss assessment (Badawi, 2003) • Threshing loss assessment • Winnowing loss assessment • Drying loss assessment (Appiah et al., 2011) • Storage loss assessment (Harris and Lindbald,1978) • Milling loss assessment (IRRI, 2009)
    • 8. Sickle Harvesting Reaper harvesting Combine harvesting Fig. 2: Harvesting Methods Assessed
    • 9. Results of Study 2- Losses during Harvesting There was no significant difference between methods of harvesting but significant differences existed among farmers at p≤0.05. Interaction between farmers and method of harvesting was also not significant at p>0.05. This means improvement of farmers harvesting practices could help reduce losses considerably irrespective of the method used. losses estimated in this study exceeded loss ranges of 1-3% reported for South East Asia (IRRI, 1997).
    • 10. a. Mechanical threshers b. Manual threshing (bambam) Fig. 4:Threshing Methods Assessed
    • 11. Results of Study 2-Losses to Threshing Rice losses due to threshing methods used in the community differed significantly (p≤0.05) for spilled and re-threshed losses Interaction for methods and farmers were significant for rethreshed losses (p ≤0.05) but losses to spillage were similar. WBT losses reported in this study far exceeded loss (6.14%) reported for Ghana by Appiah et al., 2011. Spilled losses (5.64%) and rethreshed (12.73%) losses reported in this study exceeded what Malaysian workers observed during WBT. They reported spilled loss of 1.13% and rethreshed losses of 11.7%. This means some intervention programs are needed in this community.
    • 12. Results of Study 2: Losses to Winnowing Losses to both methods did not vary from each other. However, significant difference existed among farmers during winnowing (p≤0.05). Interaction between methods and farmers were found to be significant (p≤0.05) during winnowing. Values reported in this study were far below loss of 4% reported in Philipines by Badawi (2003) and 2.5% estimated in Madagascar.
    • 13. Results of Study 2- Overall post harvest losses Post harvest stage Ranges of % Rice loss Harvesting 2.82-7.29 Threshing 3.77-24.58 Winnowing 0.23-1.53 Drying 3.73-7.32 Storage Total Average 2.19-11.12 12.74-51.84 32.29 Total post harvest losses incurred in this study (12.74-51.84%) were not consistent with losses of 10-40% reported by Satin, 1997 & FAO, 1997 However, average total post harvest loss in this study (32.29%) was found within the estimated loss by (Satin, 1997; FAO, 1997) From the study, it can be deduced that almost 33% of what farmers produced at Afife never reach the market but is rather lost during the post harvest chain.
    • 14. Results of Study 3: Physical characteristics of milled rice samples Harves ting time Daf 25 L (mm) B (mm) Shape (L/B) *TGWpaddy (g) TGWmilled (g) size sha pe 7.27±0.21a 1.75±0.08b 4.16±0.20d 25.36±0.24a 17.67±0.40c L* S* Daf 30 7.23±0.40a 1.67±0.07c 4.34±0.22e 25.95±0.38a 18.07±0.12b L s Daf 35 7.13±0.18a 1.72±0.08b 4.15±0.21d 26.78±0.34b 18.24±0.11b L s In a column, means having same superscripts do not differ significantly at 5% level of probability. L*-long, S*-slender Grain classification: 6.61-7.5 -long, >3.0 -shape (IRRI,1993), *TGW-Thousand grain weight a, b, c Grain length for all harvested rice at different dates were similar but 30 DAF differed from DAF 25 and 35 for grain breadth (p≤0.05). 25 and 35 DAF had similar shape but 30 DAF differed from them statistically. All rice harvested at different times were long and slender according to grain classification (IRRI, 1993).
    • 15. • All grain types (paddy) were found to have acceptable TGW (20-30g) according to AduKwarteng et al., 2003) but DAF 35 was found to be more acceptable and different from daf 25 and 30. • All grain types were found to have acceptable TGW of 16-20g for long milled rice according to standards set by USA regulation. • DAF 30 and 35 recorded high TGW for milled rice and differed statistically from 25 DAF. • With this, we expect rice and rice products such as flour to be higher when processed.
    • 16. Mean chromameter and other physical properties of rice Harvesting time/attribut e L* 25 DAF 30 DAF 35 DAF 71.33±0.19a 68.05±0.16b 72.33±0.13c a* +1.62±0.14a +3.75±0.09b +1.82±0.07c b* +11.70±0.57a +11.73±0.16a +11.32±0.15a Chalkiness (%) 0.03a 0.08a 0.29b 0.49a 0.10b 0.07b 0.13a 0.34b 1.14 0.02 Immature (%) Mouldy (%) Red rice (%) 0.04a 0.09 Rice types with same superscripts in a row are not significantly different at p≤0.05. L* = Lightness of kernel; a* = Redness of kernel; b* =Yellowness of kernel a,b,c 35 DAF harvested rice recorded the highest whiteness value and hence would impact positively on consumers acceptability. All the rice harvested met quality criteria (4% red rice, 6% chalky grains and 2% immature grains) for market competitiveness (Codex Alimentarius, 1990).
    • 17. Study 3: Effect of Harvesting time on physicochemical, cooking and eating quality of rice (var. Togo Marshall). • Time needed to cook rice varied with time of harvesting. Early harvested rice (25 DAF) cooked at less time but late harvested rice (35 DAF) cooked at a higher time. • Harvesting at 30 and 25 DAF had similar amylose composition but differed for 35 DAF which was least. • Harvesting at 25, 30 and 35 DAF varied extensively for ASV (p≤0.05). However, gelatinization temperature for 25 and 30 DAFs were classified as intermediate while 35 DAF was classified as high (Normita and Cruz, 2002). • Harvesting at 30 and 35 DAF compared well for KER, WAR and VER but differed from early harvested rice 25 DAF.
    • 18. Study 3: Effect of harvesting time on milling qualities of rice Head rice yield, husking yield, milling yield increased with increasing time of harvesting but decreased for broken grains. Statistically, husking yield for 30 and 35 harvested rice differed for 25 DAF harvested rice (p≤0.05). However, 30 and 35 DAF compared well for milling yield, milling degree, broken grains and head rice (p>0.05).