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Corn quality changes in hermetic storage in Sub-Saharan Africa (SSA)

Corn quality changes in hermetic storage in Sub-Saharan Africa (SSA) . Nda-Agyima K. Addae-Mensah , MSc . PhD Student Klein Ileleji , PhD. Assoc. Professor & Extension Engineer. Presentation Outline. Introduction Materials and Methods Objectives Results Summary & conclusions.

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Corn quality changes in hermetic storage in Sub-Saharan Africa (SSA)

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  1. Corn quality changes in hermetic storage in Sub-Saharan Africa (SSA) Nda-Agyima K. Addae-Mensah, MSc. PhD Student Klein Ileleji, PhD. Assoc. Professor & Extension Engineer Biomass Logistics and Particle Technology Group

  2. Presentation Outline Introduction Materials and Methods Objectives Results Summary & conclusions

  3. Introduction Inadequate drying! Problems in storage! Biomass Logistics and Particle Technology Group

  4. Introduction Corn de-husked right after harvest High humidity and limited sunshine hours Safe moisture content levels,13% mc or below are not really reached . Corn harvested at high mc levels (~30% mc) is typically dried to between 16% to 20% mc levels using open air solar drying(Weinberg, 2008) Biomass Logistics and Particle Technology Group

  5. Introduction Storage bag types PICS bag storage technology – successful and flourishing with cowpea storage (Murdock, 2012) and (Baributsa et. al. 2010) Cowpea, usually stored at very low moistures since its mostly grown in arid areas in the tropics However, little is known as to how well PICS bags will do for other grains stored at intermediate moisture levels Biomass Logistics and Particle Technology Group

  6. Mycotoxins Mycotoxin production is a significant issue for SSF in SSA. Mycotoxins have been shown to have adverse effects on human health • Suppress the immune system • Cause chronic damage to liver and kidney • Cause damage to the digestive and nervous system • Interferes with the reproductive system • Liver cancer caused by aflatoxins (naturally occurring mycotoxins) contributed to 70% of cancer related deaths in Africa (Farombi.,2006) Biomass Logistics and Particle Technology Group

  7. Research goals To systematically evaluate the effect of initial corn moisture content on oxygen depletion rate, mold growth and grain quality over time in hermetic conditions Biomass Logistics and Particle Technology Group

  8. Methods and Materials Storage tests 400 g of corn were placed in 1L glass bottles. 20 glass bottles in total were used for the preliminary study. 10 bottles were non-insulated 10 bottles were temperature insulated The stored bottles in a controlled chamber at 25C Biomass Logistics and Particle Technology Group

  9. Methods – Measurement Variables CO2and O2 levels pH (Acidity) Moisture content Water Activity Temperature Biomass Logistics and Particle Technology Group

  10. Methods : Quality tests Microbiological tests Fat Acidity tests Germination tests Biomass Logistics and Particle Technology Group

  11. Objectives This study determined the changes in quality of hermetically stored corn above safe threshold levels (14% & 22% moisture content) after 7 and 14 days of storage. Biomass Logistics and Particle Technology Group

  12. Results (Exploratory Analysis) Tests were conducted before and after Storage Analysis - Paired Sample t-tests at alpha levels of 0.05 probability levels using Microsoft Excel Grain Quality tests Fat Acidity Percent corn kernels Infected Mycotoxin (not reported) Biomass Logistics and Particle Technology Group

  13. Results: Moisture content tests Results for moisture content at 7 & 14 days at 25C, for temperature-insulated bottles Results for moisture content at 7 & 14 days at 25C, for non-insulated bottles Moisture content (%) Moisture content (%) Biomass Logistics and Particle Technology Group

  14. Results: Fat Acidity/ pH tests 7 days, 14%mc 14 days, 14%mc 7 days, 22%mc 14 days, 22%mc 7 days, 14%mc 14 days, 14%mc 7 days, 22%mc 14 days, 22%mc Biomass Logistics and Particle Technology Group

  15. Results: Fat Acidity/ pH tests 14 days, 22%mc 14 days, 22%mc Biomass Logistics and Particle Technology Group

  16. Results: Microbiological tests Percent number of corn kernels infected after 7 and 14 days of storage for non-insulated bottles Percent number of corn kernels infected after 7 and 14 days of storage for temperature insulated bottles Biomass Logistics and Particle Technology Group

  17. Carbon dioxide and oxygen measurements Non-insulated bottles NB: Temperature insulated bottles were not used for these tests Biomass Logistics and Particle Technology Group

  18. Summary and Conclusions • There were no significant changes in the number of infected kernels at 22% mc and 14% mc. • There was an increase in the percent of infected kernels from the start of storage to 7 and 14 days, respectively. • Some lessons were learned in correcting and refining our methods for bench-scale studies Biomass Logistics and Particle Technology Group

  19. Summary and Conclusions Fat acidity levels increased with increase in storage time and moisture content There will be heating of grain due to mold growth Learned from mistakes made in this study and will refine methods for long-term study of quality changes in hermetic stored corn at 14 to 22% moisture. Biomass Logistics and Particle Technology Group

  20. Acknowledgements We would like to thank Prof. Larry Murdock for helping with the Mocon device used for carbon dioxide and oxygen measurements. Biomass Logistics and Particle Technology Group

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