Authors:
Victor K. Langat, Christopher L. Kanali, Erick K. Ronoh, Stephen N. Ondimu,
Samuel N. Ndirangu, Tony Roskilly, Mohammad Royapoor, Paul Laidler |
Abstract:
Fruits are high moisture agricultural produce rendering them highly perishable hence the danger
of postharvest losses is also lurking when there are inadequate storage facilities. The losses result
from physical, chemical, and physiological changes that are triggered by the loss in moisture
content. Preservation of fruits using available and affordable technologies (such as charcoal
coolers) can benefit small-scale farmers in minimizing postharvest losses. An evaporative
charcoal cooler 4 m long, 4 m wide, and 2.5 m high providing a 40 m3
storage capacity was
utilized in the study. The cooler with a 150 mm wide cavity filled with charcoal had a perforated
pipe connected to a 1000-litrecistern raised at 2.5 m above the ground and connected to a water
pump (Pedrollo PKm 60, Italy) that kept the charcoal wet by a drip system. The pump and the
three axial fans (REC-21725 A2 W, USA) rated 180 cubic feet per minute (CFM) and 2600
revolutions per minute (RPM) were powered by fast fold thin-film PV (FFMAT-10, Renovagen,
UK) system connected to a 10-kWh rated energy hub (FFENERGYHUB-10, Renovagen, UK).
Temperature, relative humidity and product quality parameters (weight loss, total soluble solids,
vitamin C content and firmness were evaluated).The evaporative cooler temperatures reduced
significantly (P<0.05) with an average 25.0±0.37 oC and 32.1±0.99 ºC outdoors temperatures.
The cooler relative humidity increased significantly (P?0.05) averaging 76.8±1.6% and 43±2.8% for ambient conditions. The average cooling efficiency in the charcoal cooler was 83.0%.The
percentage weight loss of the avocado was 3.9% and 7.5% for the cooler and outdoors
respectively. The percentage vitamin C loss was 39.0% for the cooler and 49.6% for those kept
outside. The total soluble solids in the cooler rose from 0.5 to 1.6 oBrix and 0.5 to 2.6 oBrix in
ambient conditions. Firmness decreased from an average 65.0 N to 10.7 N and 65.0 N to 8.0 N
after 12 days for samples in the cooler and ambient conditions, respectively. In conclusion, the
evaporative charcoal cooler incorporated with thin-film PV system preserved the postharvest
quality and extended the shelf life of hass avocado.
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