Effectiveness of the solar biomass hybrid dryer for drying and disinfestation of maize

Authors: BOSOMTWE, AUGUSTINE - Kwame Nkrumah University Of Science And Technology; DANSO, JAMES - Kwame Nkrumah University Of Science And Technology; OSEKRE, ENOCH - Kwame Nkrumah University Of Science And Technology; OPIT, GEORGE - Oklahoma State University; MBATA, GEORGE - Fort Valley State University; Armstrong, Paul; Arthur, Franklin; Campbell, James - Jim; MANU, NAOMI - Kwame Nkrumah University Of Science And Technology; MCNEILL, SAM - University Of Kentucky; AKOWUAH, JOSEPH - Kwame Nkrumah University Of Science And Technology

Submitted to: Journal of Stored Products Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/27/2019
Publication Date: 8/15/2019
Citation: Bosomtwe, A., Danso, J.K., Osekre, E.A., Opit, G.P., Mbata, G., Armstrong, P.R., Arthur, F.H., Campbell, J.F., Manu, N., McNeill, S.G., Akowuah, J.O. 2019. Effectiveness of the solar biomass hybrid dryer for drying and disinfestation of maize. Journal of Stored Products Research. 83:66-72. https://doi.org/10.1016/j.jspr.2019.05.011.
DOI: https://doi.org/10.1016/j.jspr.2019.05.011

Interpretive Summary: Solar drying to reduce grain moisture content can be used in developing countries to dry grains such as corn (maize) prior to storage, but in countries like Ghana where harvest can occur during rainy periods solar drying alone may not be sufficient. If corn is not properly dried before storage, there is an increased risk of stored product insect infestation and fungal contaminant, primarily aflatoxin. Scientists at Kwame Nkrumah University of Science and Technology (KNUST) in Kumasi, Ghana, and collaborators at different US Universities and the USDA-ARS, conducted experiments to determine feasibility of a solar biomass hybrid dryer. The hybrid dryer utilizes the burning of available biomass such as crop residues and timber scraps in combination with solar drying to maintain high temperature and low humidity and reduce drying times. Scaled up hybrid solar dryers were evaluated and results showed that higher temperatures and lower moisture content were obtained in corn held inside the experimental dryer compared to corn that was only sun-dried. Even though the target temperature of 50°C for 4 h was attained, complete mortality of insects was not achieved in the hybrid solar dryer, although survival was less than in the solar only dried corn. Further research into longer exposure times to the high temperatures is needed to determine if complete control can be achieved. The solar biomass hybrid dryer could be used for drying and for possible disinfestation of grain in Ghana, and commercial adoption of these dryers is expected in the future.

Technical Abstract: The Solar Biomass Hybrid Dryer (SBHD) is a new technology developed in Ghana for grain drying and utilizes biomass (agro-residues, timber scraps, etc.) along with solar drying, and is especially useful for drying during rainy periods of the year when solar drying cannot be relied on. This study assessed the effectiveness of a 5.0-MT SBHD comprising a solar tent and a furnace for thermal drying and disinfestation of maize. Mortalities of adults of Sitophilus zeamais (Motschulsky), Tribolium castaneum (Herbst) and Cryptolestes ferrugineus Stephens were assessed. Additionally, mortalities of immatures of these three species were assessed. Internal and cage temperatures (°C) in the SBHD, under sun drying (SD) and laboratory (control) conditions were monitored, as were moisture content (MC) and thermally damaged kernels (TDK) (%). During the 7-hour experiment, mean internal temperatures in the SBHD, SD and laboratory were 52.29 ± 1.04°C, 41.43 ± 0.78°C and 30.32 ± 0.15 °C, respectively. Similarly, temperatures in cages in the SBHD (49.47 ± 1.04°C) were higher than those for cages in the laboratory (29.93 ± 0.15°C) and under SD (38.16 ± 0.55°C). Grain MC reduction values in the SBHD, SD, and laboratory were from 20.3–12.6%, 20.3–15.1%, and 20.3–17.4%, respectively; this corresponded to grain MC reduction rates of 1.1%, 0.74%, and 0.4% per hour. Complete (100%) mortality of S. zeamais and C. ferrugineus adults was achieved in only the SBHD; some immatures of all three species survived in all three treatments. However, survival of immatures was higher in the laboratory, followed by SD, and lowest in the SBHD for all three species. Percent TDK was higher in the SBHD (6.67 ± 0.88) than SD (3.33 ± 0.33) and laboratory (2.67 ± 0.33). These data show that the SBHD is effective for both drying and disinfestation of grain.