Impact of raising frozen food temperature by 3°C on cold-chain sustainability

As ACES (Africa Centre of Excellence for Sustainable Cooling and Cold-Chain) explores the opportunity for frozen food in Africa, PhD student Lakshmi Wasana Gunathilaka Jayaweera Arachchilage investigates the impact of raising frozen food temperatures by 3ºc.

The cold-chain is the backbone of modern food systems, making it possible to store, preserve, and distribute food efficiently across the globe. Cold-chain integrity directly affects food safety, nutrition, access to food, and global food loss, which exceeds 30% of post-harvest yields. Food production alone is responsible for approximately one-quarter of global greenhouse gas emissions, meaning that food lost or waste embodies substantial environmental costs before it even reaches consumers.

UK households still discard around 4.2 million tonnes of avoidable food each year, including approximately 630,000 tonnes of items that could be frozen, such as bread and meat, representing a significant missed opportunity to reduce waste. The value of this freezable food in the UK alone is estimated at £2.3 billion annually, highlighting both economic and environmental benefits of greater reliance on freezing. According to the Food and Agriculture Organisation (FAO), carbon emissions associated with global food waste are estimated at approximately 3.3 gigatons of CO₂-equivalent per year, accounting for around 7% of total global greenhouse gas emissions.

Frozen foods can contribute to a reduction in emissions by extending shelf life, reducing spoilage, and lowering food waste across supply chains and households. While consuming locally produced food is often associated with lower emissions, this is not always possible when foods are not available outside their natural growing season. To meet year-round demand, locally produced out-of-season foods may require energy-intensive production methods, such as heated greenhouses or rapid growing cycles, which can significantly increase greenhouse gas emissions compared with producing the same foods seasonally in suitable regions. Freezing provides an effective alternative, allowing foods harvested during their natural season to be preserved safely for several months. This reduces the need for continuous out-of-season production and limits reliance on high-emission transport modes, such as air freight. Transporting food by air emits around 50 times more greenhouse gases than transporting the same quantity by sea. For foods shipped by sea, transportation typically contributes only a small proportion of the overall carbon footprint. Frozen foods can therefore offer environmental advantages, as they can be transported efficiently over long distances by ship and stored for extended periods with minimal spoilage.

However, other parts of frozen supply chains consume significant energy and have environmental impacts. Frozen food is typically stored at –18°C, a long-standing industry standard that comes with high energy costs. Increasing attention is now being given to whether the industry can safely operate at slightly higher temperatures without compromising quality. Evidence from recent modelling suggests that a modest increase to –15°C may still provide stable, safe storage for many frozen foods while delivering substantial energy savings.

A PhD at London South Bank University has just been started to assess the feasibility of moving to a higher frozen food storage temperature. This project’s primary aim is to establish a robust, contemporary scientific basis for determining whether frozen foods can be stored safely, sustainably, and with acceptable quality at slightly higher temperatures than the current –18°C standard. The study examines real-world practices across the supply chain and looks at product-level effects such as nutrient retention, texture, ice crystal behaviour, colour, and shelf life.

Frozen food chains are relatively scarce in Africa, limiting access to high-quality, preserved foods and contributing to food loss. Importantly, building frozen chains from the ground up in Africa offers the opportunity to design systems specifically for local requirements. This flexibility could allow slightly higher storage temperatures, reduce energy demand and costs while maintaining food safety and quality. By tailoring cold-chains from the outset, we can create more sustainable, efficient, and resilient supply systems for foods.