INNOVATION OF COLD STORAGE TECHNOLOGIES BY UON POSTHARVEST RESEARCH TEAM

To address the challenge of lack of affordable cold storage for smallholder farmers, the University of Nairobi’s Multi-disciplinary Postharvest Research Team has been conducting adaptive research on innovative and affordable cold storage solutions. After years of on-station and on-farm adaptive research supported by various development partners including United States Agency for International Development (USAID), The Rockefeller Foundation and the Kenya government through the National Research Fund, several low-cost cold storage technologies have been validated for wide-scale adoption by farmers and other practitioners. 

To address the challenge of lack of affordable cold storage for smallholder farmers, the University of Nairobi’s Multi-disciplinary Postharvest Research Team has been conducting adaptive research on innovative and affordable cold storage solutions. After years of on-station and on-farm adaptive research supported by various development partners including United States Agency for International Development (USAID), The Rockefeller Foundation and the Kenya government through the National Research Fund, several low-cost cold storage technologies have been validated for wide-scale adoption by farmers and other practitioners. 

In the effort to build capacity and create awareness about these innovative technologies for cold storage the University of Nairobi Postharvest Research team recently established the Innovative Cold Storage Technologies: Research, Training and Demonstration Unit.

Lack of cold storage is one of the factors that contribute to high postharvest losses in perishable commodities including fruits and vegetables. For majority of smallholder farmers involved in horticultural production conventional cold rooms are beyond their means. Furthermore, the scale of production among smallholders does not make economic sense to invest in individual cold storage.

The unit has been established with support from various partners including the National Research Fund (NRF-Kenya); the Consortium for Postharvest Loss and Food Waste Reduction (funded by the Foundation for Food and Agricultural Research (FFAR); the SolCOOL Project (Solar Powered Cold Food Chains Food Waste Reduction and Value Addition) which is funded by UK-Innovate; and Massachusetts Institute of Technology (MIT) funded by J-WAFS. The demonstration unit houses various innovative cold storage technologies:

Improved charcoal cooler

This is a modular design of a charcoal cooler which has been designed by Dr. Duncan Mbuge and Mr. Eliakim Mwachoni from the Department of Environmental and Biosystems Engineering, UoN. Charcoal coolers operate on the principal of evaporative cooling whereby hot air blowing through/over a porous medium such as charcoal which is wetted results in a cooling effect as the water evaporates from the medium taking away heat (heat of vaporization) from the environment. Subsequently the air that enters the inside of the chamber is cool and humid (Figure 1.)

Results from our adaptive research studies show that evaporative cooling can achieve temperatures up to 150C lower than the ambient air temperature, depending on the season and time of day. The demonstration unit features an improved design of the charcoal cooler (Figure 2). The walls are made from fiber glass to enhance the structural strength and durability. In addition, the fiber glass walls make the charcoal cooler more hygienic compared to the common charcoal coolers whereby the ‘naked’ charcoal is supported by chicken wire which is prone to rust. The 4 X 4 M charcoal cooler can accommodate up to 200 standard bread crates filled with fresh produce. 

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