Enhancing the shelf life of injera: design of an evaporative cooler clay chamber derived from local clay in Bahir Dar, Ethiopia

Abstract

Injera is Ethiopian ethnic traditional staple food, made from teff and other crops. The country’s superfoods are highly regarded in many Western countries for their excellent nutritional properties (‘very low gluten’), and mineral composition. Injera provides sufficient conditions for fungi to grow and ruin injera by changing the texture and making it inedible. This study aimed to develop an evaporative cooler clay chamber (ECCC) used to extend the shelf life of injera by controlling temperature and relative humidity (RH). This system is an economical and efficient way to lower the temperature and increase RH. The results show the maximum daily ambient temperature reduced from 28.98 °C to 22.90 °C and increased the RH of the storage chamber from 28.78% to 80.94%, respectively. The temperature drops up to 6.08 °C, and the RH rises to 52.16% observed. Additionally, the effects of temperature, RH and potential of hydrogen were studied for identified rotten injera and designed for injera storage. ECCC can store freshly made injera for 9 days before any visible mould stains appear, significantly reducing weight loss with an average cooling efficiency of 79.31%. Therefore, this study might help to develop low-cost cold storage for injera preservation at farms end in Ethiopia.

Implementation and Performance Evaluation of a Community-Scale Adobe Evaporative Cooling Chamber for Vegetable Preservation

“…The material and shape of the chamber have been addressed, showing their effect on temperature drop and food preservation [6,[11][12][13][14]17,18,23,26]. Experimental studies give ideas for materials [5,8,14,21,[27][28][29], and some of them address issues of implementation.…”

“…In developing countries, mainly in remote areas, the difficulties increase, and it is necessary to facilitate the deployment using low-cost, abundant, and/or cost-free materials that are locally available and culturally accepted [28,30]. In Vala's review, most of the proposed ECs have brick walls, while some are made of metal or wood, with just one unit reportedly made of clay [19] on the very small scale of 0.6 × 0.52 × 0.85 m. Soil/clay is a great opportunity to build evaporative coolers [21,26,29,31] because of its hygroscopicity; it can be found everywhere, and is mostly free.…”