3:30pm - 3:50pm
Development of safe storage guideline of hemp seeds
University of Manitoba, Canada
Safe storage guidelines are a common tool used to guide farmers to store grain at right temperatures and moisture contents in order to avoid any quantity and quality loss. In Manitoba, Canada, approximately 9% of stored hemp seeds are lost during harvest, handling, and post storage. Therefore, guidelines for hemp seed storage are required. This study determined the effect of temperature (20, 25, 30, 35 and 40℃), seed moisture content (relative humidity: 90, 80, 70 and 60%), and storage time (stored for 24 wk) on germination of hemp seeds (variety Finola). Moisture content and germination of the hemp seeds were determined every week. It was found that all the measured variables (relative humidity, temperature, and time) had a significant effect on the germination. Relative humidity and temperature proportionately increased moisture content as well as the faster decrease of germination. There was 85% decrease in germination for samples at ≥80% RH stored at ≥25℃ as well as 95% decrease for ≥35℃ at ≥70% RH in 7 wk. Hemp seeds with lower relative humidity (70% & 60%) can be stored at temperatures ≤25℃ with higher than 70% seed germination for 24 wk. Based on the 20% initial germination loss, safe storage guideline of hemp seeds was developed.
3:50pm - 4:10pm
FEM simulation of RF selective heating of red flour beetle in stored canola seeds and effect of voltage on the selective heating
University of Saskatchewan, Canada
Using a finite element method based commercial simulation package (COMSOL Multi-physics) radio frequency (1.5 kW, 27.12 MHz) selective heating of red flour beetle in two different volumes of bulk canola seeds at 5%, 7%, 9%, and 11% moisture contents was simulated. The electric field formation, dielectric heat generation, non-isothermal fluid flow, and heat transfer including surface to surface radiation were solved simultaneously. The simulated and the measured temperatures of the seeds were compared with the different moisture contents and volumes of the seeds. Similar comparison was also conducted for the insects and the seeds. The differences between the simulated and the measured temperatures of the seeds were not more than 17.4%, 13.4%, 8.08%, and 19.0% for the small volume seeds and 14.8%, 15.6%, 19.5%, and 18.8% for the large volume seeds at 5%, 7%, 9%, and 11% moisture contents, respectively. Non-uniform radio frequency heating of the seeds was observed regardless of the moisture content and the volume of the seeds. The radio frequency selective heating of the insects was most effective for the small volume seeds at 11% moisture content. The temperature of the insects was 14.6°C (maximum) higher than the temperature of the seeds. The radio frequency selective heating of red flour beetle in the canola seeds was be improved with higher electric voltage of top electrode according to further simulations.
4:10pm - 4:30pm
Moisture sorption and desorption isotherms of stored hemp seeds with different percentages of dockages
University of Manitoba, Canada
Desorption and adsorption isotherms of stored hemp seeds are required for the safe storage of hemp seeds. Moisture sorption and desorption isotherms of newly harvested hemp seeds (variety Finola) with 0%, 5%, 10%, 15%, 20%, and 25% of dockages were determined at 10°C, 20°C, 30°C, 40°C, 50°C and 60°C with 32% to 91% RHs. The constant RHs were created by using six saturated salt solutions in desiccators. Different models recommended by the ASABE standard and published in the literature were fitted to the determined equilibrium moisture content and RH data. The best-fitted equation was selected based on the coefficient of determination (R2) of the regression and smallest least square between predicted and measured equilibrium moisture contents. The selected mathematical models were the following equations: modified Henderson, Modified Chung-Pfost, Modified Halsey, Modified Oswin, and Guggenheim-Anderson-deBoer (GAB) equations.
hemp seeds, moisture sorption, desorption, isotherm, mathematical modelling.
4:30pm - 4:50pm
Dockage and fine material distribution in bulk wheat stored in a farm bin
1University of Manitoba, Canada; 2Agriculture and Agri-Food Canada
The presence of dockage and fine materials in a stored grain bulk influences the grain quality management. For example, the distribution of dockage inside stored grain bins is not uniform throughout grain bulk, so different locations exhibit different resistance to airflow leading to non-uniformity in aeration and grain drying. Distribution of dockage and fine materials inside a farm bin filled with hard spring wheat (grade No. 2) was studied. The farm bin (10 m diameter and 11 m height from the floor to the top vent) was filled from the top vent using a grain auger. After filling, wheat samples were collected from 13 locations inside the bin; nine locations along a diameter of the bin from one end to another and four locations along the perpendicular diameter. The collected samples were then separated into three fractions by sieving: wheat grains, dockage larger than wheat (coarse materials), and dockage smaller than wheat (fines). The percentage of coarse and fines by weight was higher near the wall than the corresponding locations towards the centre.