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Warming up to -15°C: A more climate-friendly freezing standard is gaining momentum

A modest shift in the standard freezing temperature for food – from -18°C to -15°C – could lead to significant energy savings, reduced carbon emissions, and cost efficiencies, all while maintaining food safety and quality.

A movement supporting the proposal with the aim to make the frozen food industry more sustainable, called the Move to Minus 15°C, was launched at COP28 in December 2023 by logistics firm DP World.

The initiative has recently been backed by major industry players, including Danish food company Danish Crown, cold logistics operator Constellation Cold Logistics, and Indian cold storage and logistics solutions company Indicold.

With other companies like Nomad Foods’ a European frozen food manufacturer, leading the charge, this change could mark one of the most significant updates to freezing practices in nearly a century. In parallel, Unilever's efforts to reformulate ice cream for warmer storage further underscore the viability of this shift.

-18C: An arbitrary standard?

The current industry standard of freezing food at -18°C was established nearly a century ago as a temperature that provides a reliable margin for food safety, ensuring that food remains frozen solid and preventing the growth of microorganisms that cause spoilage and foodborne illnesses. However, there was no rigid scientific basis for the exact number; as 18C is equivalent to 0 Fahrenheit, one researcher suggests that this was picked as “probably a round, easy number to remember.”

Nonetheless, this standard has been adopted globally, becoming the norm for frozen food storage and transportation. However, as energy efficiency and environmental sustainability have become more pressing concerns, experts have begun to question whether this standard is still necessary or if a slight increase to -15°C could offer substantial benefits.

Energy savings and environmental impact

Research conducted by the International Institute of Refrigeration has shown that raising the standard freezing temperature to -15°C could reduce energy consumption by 10-12%. This reduction is significant for food manufacturers, translating into major cost savings. Additionally, the change could cut global carbon dioxide emissions by 17.7 million tonnes annually, the equivalent of taking 3.8 million cars off the road.

The shift to -15°C could also improve supply chain efficiency. Lower energy requirements for maintaining this temperature would allow for more flexible and cost-effective logistics. Companies like Nomad Foods are exploring how this change could enhance their operations, making the supply chain more responsive and efficient.

More are joining the Move to -15°C

The Join the Move to -15°C initiative has gained substantial traction since its launch, with a growing coalition of supporters from across the global food and logistics industries. Nomad Foods has been at the forefront of this movement. The company, known for brands such as Birds Eye, Findus, and Iglo, completed an 18-month pilot study in collaboration with Campden BRI, a food science and technology organisation. The study tested the effects of storing various frozen products, including poultry, fish, vegetables, and pizza, at temperatures ranging from -18°C to -9°C. The results showed no significant impact on food safety, texture, or nutritional value at -15°C, further validating the viability of the new standard.

Food product quality and safety considerations

While the proposed temperature shift is expected to have minimal impact on most frozen products, specific items show different levels of sensitivity to temperature changes. The Nomad Foods and Campden BRI study offers detailed insights into how different types of food behave under varying storage temperatures, from -18°C to -9°C.

Poultry and meat products showed remarkable stability even at the higher end of the tested temperature spectrum. When stored at -15°C, there was no noticeable difference in texture, moisture retention, or flavour compared to storage at -18°C.

Coated and natural fish products maintained its quality well at -15°C. However, when the temperature was increased to -12°C, a slight change in the sensory properties of salmon fillets was noted, with minor textural differences, which suggests that fish products may be somewhat more sensitive to temperature variations than meat.

Vegetable products, including a mix of frozen vegetables, showed varying responses to temperature increases. At -15°C, there was no significant impact on texture or taste for most vegetables. However, when the temperature was raised to -9°C, a decrease in Vitamin C levels was observed.

Reformulating ice cream for -12C

Ice cream has traditionally been one of the few frozen foods that required storage at -18°C to maintain its quality. The formation of small ice crystals at this temperature is critical to preserving the smooth texture that consumers expect. However, food multinational Unilever has reformulated its ice cream products to allow ice cream to be stored at -12°C without compromising its quality, which could significantly alter the requirements for cold chain logistics.

Unilever has made twelve reformulation patents for different ice cream products, including ice creams on a stick, coated ice creams, water ices, and mini cups available as free, non-exclusive licenses to competitors.

These reformulations involve increasing firmness by rebalancing the ingredients in the ice cream to have a greater ice content, which helps maintain the firmness of ice cream at the serving temperature.

The reformulation forms part of the company’s Climate Transition Action Plan. Ice cream freezer greenhouse gas emissions form one-tenth of Unilever’s footprint, which makes the estimated 20-30% energy reduction per freezer resulting from the reformulations an important contribution to its sustainability targets. Unilever is conducting trials in Indonesia and other markets between 2024 and 2027 with reformulated and naturally resilient ice cream products to test if the new standard can be implemented globally.