19 research outputs found
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Drying of freshly harvested almonds using a stockpile heated and ambient air dryer (SHAD) with an air distributor -part 2
An almond stockpile heated and ambient air dryer (SHAD) without an air distributor, did not adequately distribute air throughout the stockpile. Therefore, this project evaluated the effect of adding an air distributor within the SHAD A-frame as an alternative method to conventional windrow drying. Three stockpile drying tests were performed using ‘Nonpareil’, ‘Winter’, and ‘Monterey’ almond varieties with different initial (fresh) weights and kernel dry-basis moisture contents (MC) equal to 4763 kg and 11.8%, 2585 kg, and 11.5%, and 6849 kg and 21.5%, respectively. All tests were directly compared to conventional windrow drying. Almond quality parameters, including kernel MC, color, lipid oxidative stability, peroxide value, free fatty acid content, internal cavities, and insect injury were measured before and after drying. The SHAD with the air distributor properly maintained almond quality, while uniformly dehydrating almonds to the desired MC of ≤6 % within 7 days. Conventional windrow drying took up to 13.6 days, and the desired final MC was only achieved with the ‘Monterey’ variety. Thus, the SHAD fitted with a well-designed air distributor can be used to dehydrate almonds in a stockpile as an alternative to conventional windrow drying
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Development of a Stockpile Heated and Ambient Air Dryer (SHAD) for Freshly Harvested Almonds
Dust generated by farming activities is a safety hazard to farmworkers and an environmental contaminant. During the almond (Prunus dulcis) harvest in California, dust is primarily generated by the mechanized movement of almonds disturbing the bare soil of the orchard floor, during the sun-drying, windrowing process, and as they are transferred into trucks for transport to processing facilities. Off-ground dust-less harvesting will only be achieved when the almond industry adopts feasible mechanical drying methods. Therefore, a stockpile heated and ambient air dryer (SHAD) was developed to determine the feasibility of dehydrating almonds (Var. ‘Monterey’). A stockpile containing 4,155 kg of almonds was created and almonds were dehydrated from their initial 12.6% almond kernel dry-basis moisture content (MCdb) to final MCdb of 6.04%. Drying was achieved as a combination of heated air at a temperature of 55°C in the drying plenum with airflow of 0.078 m3/s per m3 of fresh almonds. After drying, almond quality parameters were measured, including damage by molds or decay, insect injury, and presence of internal cavities. Drying energy consumption, cost, and performance indicators were also determined. The differences in MCdb between the bottom, middle, and top layers of the almond stockpile were significant (p ≤ 0.05). Post-hoc Tuckey test was conducted which indicated that the MCdb in the top layer was significantly lower than almond MCdb in the middle and bottom layers. Results showed that damage by molds or decay, insect injury, and internal cavities were 1.81%, 0%, and 1.77%, respectively, after drying. Therefore, the overall almond quality was not compromised. The drying process cost $11.65 per tonne of the initial weight of almonds with a Specific Moisture Extraction Rate (SMER) of 0.64 kg/kWh, Moisture Extraction Rate (MER) of 1.02 kg/h, and a Coefficient of Performance (COP) of 1.33. Comparison with other dryers in the literature shows that SMER and MER were within limits. However, a low COP was observed