Spray-dried coffee and freeze-dried coffee powders are well-known staples in your local supermarket. Freeze-dried coffee has characteristic shard like grains, whereas spray-dried particles are generally smaller and more spherical. At least in the UK, where such soluble coffees are more popular than on the continent, there is a general perception that freeze-dried coffee is more premium. These two methods of producing instant coffee have been around for decades and are widely used due to their efficiency and the quality of the final product. However, both processes are energy-intensive, which has significant implications for cost and environmental impact.
Freeze-drying involves freezing the coffee extract to around minus 40 degrees Celsius. Once frozen, the extract is ground into fragments and placed in a vacuum chamber where it is gently heated. The combination of low pressure and heat causes the frozen water in the coffee to sublime, i.e. transition directly from a solid to a gas, leaving behind dry coffee granules. Freeze-drying is known for preserving the flavour and aroma of the coffee better than spray-drying since the volatile compounds are not so readily lost. However, it is also a highly energy-intensive process. The freezing, the grinding in a very cold environment, vacuum application, and controlled heating all require significant amounts of energy.
In spray-drying, on the other hand, a wet coffee extract is pumped and sprayed into a hot chamber. The water in the extract evaporates almost instantly due to the high temperature, leaving behind tiny droplets of coffee solids that fall to the bottom of the chamber. This method is quick and efficient, but it requires energy to pump the viscous extract, heat the chamber and maintain the high temperatures needed for evaporation. Volatile coffee aroma and flavour compounds can be lost in the hot environment, potentially affecting the perceived quality of the final product. However, the energy cost of spray-drying, while still high, is typically much less than that of freeze-drying.
The specifics of these processes may not matter to the average consumer – after all, they just want a tasty cup of coffee – but the energy consumption involved in making instant coffee is substantial. Whether it’s the pumping, grinding, heating, freezing, or applying a vacuum, each step in the production of these coffee powders consumes energy, which adds to the overall cost of the process. This is a critical consideration for manufacturers, especially as energy prices fluctuate and environmental concerns become more pressing.
Over the years, there have been numerous patents proposing alternative drying techniques for coffee. These have included, for example, using water absorbents to contact-dry a high-solids extract and spray-freezing. There have also been countless patents directed to making spray-dried coffee powders look like freeze-dried coffee powders (such as by sintering) – this would give the appearance of freeze-dried coffee at a lower energy cost – and there are also countless patents directed to improving the flavour and aroma of all soluble products. Despite the innovative ideas presented in these patents, none of the alternative drying techniques have become mainstream yet. This could be due to various factors, including the cost of implementing new technologies (huge CAPEX for new plants and processes), the scalability of the processes (it is hard to imagine using absorbents on such a large scale), and the ability to maintain the quality and consistency of the final product. However, there have been plenty of smaller innovations aimed at improving the efficiency of existing drying processes – this is where I expect to see more patents filed over the coming years. Even a 1% energy saving can be significant when applied across the entire production process. Given that the soluble coffee market is projected to be worth $32 billion in 2024, any improvement in energy efficiency can have a substantial impact on both the bottom line and the environment. A company with lower production costs is always in a stronger competitive position.
While spray-dried and freeze-dried coffee remain the dominant methods of producing instant coffee, there is a clear drive towards improving the energy efficiency of these processes. The high energy consumption presents both a challenge and an opportunity for innovation. As the soluble coffee market continues to grow, the importance of energy efficiency will only increase. By investing in new technologies and optimizing existing processes, manufacturers can reduce costs, minimize their environmental impact, and meet the evolving demands of consumers. The future of coffee production lies in finding the balance between efficiency, sustainability, and quality, ensuring that we can continue to enjoy our favourite beverage while also protecting the planet.
Of course, the drive for energy efficiency is not limited to the coffee industry. It is a trend that can be seen across the entire food and beverage sector. Manufacturers are constantly seeking ways to reduce energy consumption, lower costs, and minimize their environmental footprint. This is driven by a combination of regulatory pressures, consumer demand for more sustainable products, and the financial benefits of reducing energy use. Consumers are increasingly aware of the environmental impact of their food choices and are demanding more sustainable products. This can be seen in the popularity of organic, fair-trade, and sustainably sourced products and packaging. Manufacturers that can demonstrate a commitment to reducing their environmental footprint are likely to gain a competitive edge in the market.
