A Cooling Atlas for preserving fruit and vegetables in low- and middle-income countries

Preserving fruit and vegetables after harvest is especially relevant for low- and middle-income countries (LMIC) for food and nutrient security, reducing poverty, and increasing smallholder farmers' access to markets further afield. Cooling is one of the most impactful postharvest preservation methods, particularly when powered by renewable energy. A wide variety of cooling technologies exist, though only a subset is sufficiently advanced to present commercially viable deployment options in LMIC, of which only a smaller subset is widely known. Active cooling based on mechanical vapor compression is often considered the most commonly used solution. However, in LMIC, many structural and case-specific challenges limit their widespread use. Therefore, deploying alternative active and passive cooling technologies from a technical, financial, social, environmental, and political context could be more suitable. However, a key knowledge gap is that many active and passive technologies are not well-known and are, thereby, in limited use. Our objective was to compile existing options to raise awareness of these promising cooling solutions for LMIC. These include multiple active cooling, passive cooling, and auxiliary technologies that prevent heat gains or regulate the incoming heat, for example, by thermal heat storage or ventilation. The main outcome of this work is a compilation of these existing cooling solutions, listing the advantages and disadvantages and the physical processes underpinning how they provide cooling. We also have developed a selection matrix for the different technologies according to specific criteria. With that, we created a multifactorial evaluation for the technology spectrum for a certain country that can help stakeholders choose the right technology or a combination of technologies. Key factors here are cost, ease of installation, potential for scalability and adaptability, operation and maintenance, energy supply, energy use and storage, cooling process, cooling performance, suitability for food types, market accessibility, demand, and suitability for adoption by potential producers. The Cooling Atlas aims to provide evidence for decision-makers and program implementers to make informed investment and implementation decisions. Our Cooling Atlas encompasses existing relevant cooling solutions for LMIC. Choosing the right cooling technology for a specific value chain and use case should be carefully evaluated before implementation. It should be a holistic solution to increasing food and nutrition security and safety.