A key part of coffee production, roasting is the process by which green coffee beans are converted into the fragrant, crisp, dark brown format that most of us are familiar with. In this feature, Refreshment takes a look at the latest coffee roasting technologies, designed to help improve flavour and functionality both for operators in the hospitality sector and for coffee drinkers at home.

Roasting is central to any coffee manufacturing operation, because it is this process that creates the physical bean properties that determine the flavour of the eventual beverage. Once roasted, the coffee beans are ready for grinding and brewing.

According to market research agency Mintel, the main purchase drivers for coffee in 2024 remain taste and indulgence. “The goal for coffee brands is to combine both taste and indulgence with sustainable practices,” a recent report stated.

The coffee shop and barista scene, as well as the at-home market, is seeing a new, growing preference for artisanal roasting and new freshness concepts. Consumers are becoming increasingly aware of the importance of roasting and its impact on the flavour of their beverage, making the type of roast and preparation method key factors in their choice.

Instruments for success

The aroma and flavour of coffee is developed as a result of chemical reactions brought by the roasting operation conditions. This means that the length of the roast and the temperature at which the beans are roasted are important factors in the coffee’s final taste, so ensuring they are accurately measured is key to roasting success.

Jason Webb, managing director at digital thermometer manufacturer Electronic Temperature Instruments (ETI) told Refreshment: “Each blend of coffee produced has to be roasted to a very specific temperature to protect and bring out the flavour profile. These have to be carefully monitored to ensure a consistent and flavourful roast.”

ETI’s temperature equipment, for example, allows staff to keep a close eye on each roasting machine, which can soar to temperatures above 200°C.

Webb continued: “Similarly to searing a steak, the final phase after the high-heat cycle involves slowly roasting the beans at a low temperature to ensure it’s an even roast all the way through.

Temperature is an essential part of coffee roasting and being able to carefully oversee each phase using thermometers and temperature probes means roasteries can ensure consistent flavours and precision control every time.”

Kendricks Coffee Roasters, a Worthing, UK-based coffee roaster that uses ETI equipment, added: “From start to finish as a company, monitoring temperature is so critical. We follow strict guidelines and regulations around the processes we monitor, and record every batch we roast and produce. We want drinking our tea and coffee to be a pleasurable experience.”

Smart technology

Whether the aim is a large volume of coffee beans with a consistent flavour, or a small-scale, specialist batch, the practical skills and knowledge of the roaster are essential. However, in recent years there has been growing use of automation to streamline the process, with new technology providing tools to help roasters accurately predict roasting times and temperatures.

Technology driven by artificial intelligence (AI) can help roasters to control the roast as it develops, enabling them to more accurately control the flavour profiles of the end product.

For example, Cropster’s Roasting Intelligence software aims to make roasting ‘simple and easy’ by providing access to real-time data during the roasting process. This allows roasters to make precise, controlled adjustments to roasting variables.

The user can create detailed reference roasts and profiles to control all the variables in their roast process. A highlight of the software is the ‘First Crack Prediction,’ which uses AI technology to highlight when the roaster can expect the ‘first crack’ to occur. In roasting terminology, ‘first crack’ is a cracking sound heard when the coffee beans have expanded and the moisture has begun to evaporate from the beans. The moisture forms steam pressure that forces the beans to crack open. This point is widely considered to have a significant impact on the development of aroma and flavour.

While the financial investment in AI-powered roasting technology can be high, the cost can be offset by savings in other ways: for example, increased accuracy, less wastage and more effective time management.

The rise of home roasting technology

Today’s consumers are more aware than ever of the sustainability, transparency, locality and freshness of their coffee. The development of the speciality coffee industry and artisan roasting, alongside green beans becoming more readily available in affordable and smaller quantities, has led to a growing interest in consumers experimenting with flavours and freshness by roasting their own coffee beans at home. The freshness of the roast is a vital factor in the depth and complexity of the brewed coffee.

Emily Jackson, manager at Ikawa Home, a manufacturer of home roasting systems, told Refreshment that more consumers are realising that roasting coffee at home is possible.

“With consumers becoming more aware of the possibilities of coffee roasting, they are more attuned to flavours and how roasting coffee in a different way can eke out different flavours that may be to their preference,” Jackson explained. “With all of the lockdowns during the pandemic, the daily coffee drinkers began to have to prepare coffee themselves at home. Through necessity, these coffee drinkers began to seek out coffee gear and techniques that have suited them best – some consumers have pivoted to zero waste coffee products along with other more sustainable coffee solutions.”

Ikawa says it aims to make “home coffee roasting commonplace by making it easy, enjoyable and accessible”.

The Ikawa Home Roasting System allows roast recipes to be tailored to the consumer’s taste preferences with recommended recipes and a guided edit mode. The home roasting system uses convective heat transfer along with 100% digital read on temperature and feedback through custom firmware and a bluetooth connected app.

“The consumers who are roasting at home are our target demographic for the IKAWA Home Roasting System,” Jackson added. “I would hope that the future of this emerging market is to open up the prospect of roasting coffee at home to a larger audience with greater accessibility and a wallet friendly price point.”

Cormac Henry, principal global food and drink/ purchase intelligence analyst at Mintel, believes that technological innovation will be key to creating the perfect brew at home in five years and beyond. “Data-sharing technology between bean grinders and coffee machines holds the potential to allow consistently perfected brews at home,” he concluded. “Already used by foodservice providers in Germany, synced coffee equipment could reach consumers’ homes as the technology becomes more affordable.”

A fresh perspective

Based in Hawaii, Big Island Coffee Roasters places quality, sustainability and community at its core. Its local coffees are ripe harvested, handcrafted, milled in small batches and roasted-to-order. The independent roaster was also the proud winner of the Speciality Coffee Roaster category at the 2023 FoodBev World Coffee Innovation Awards. Here, Refreshment editor Bryony Andrews asks co-founder Kelleigh Stewart to share some of the knowledge and insight gained from 14 years of hard work.

Why is using freshly roasted coffee important for achieving the best flavour and quality in a cup?

Using freshly roasted coffee is critical for preserving the intricate flavours and aromas that create distinction between coffees. It can connect you to the practices of the farmer and the culture of coffee handling in a region. It’s also important because, well, stale coffee tastes awful and the flavours can only be masked with heaps of sugar and cream. Once you’re used to the flavours of freshly roasted coffees, the stale coffee will ruin your morning.

Pro tip: just as butter can turn rancid when it’s on your counter for too long, the oils of coffee will also take on a stale, papery flavour over time when exposed to oxygen, light or moisture. The process is called oxidation. Darker roasts are prone to faster oxidation and staling because the oils are pushed outside of the cellular matrix of the coffee bean. In other words, darker roasts stale faster than medium and light roasts.

What are today’s consumers seeking in terms of flavour, quality and experience from their coffee?

They’re looking for coffees they can feel good about. They’re looking for coffees that they don’t have to drown in syrups and cream to make palatable. They’re excited about coffees with character that leave a clean, naturally sweet taste in their mouth, rather than over-roasted, bitter or ashy aftertastes.

What are the advantages and disadvantages of large-scale commercial roasting compared to small-scale or artisan roasting?

Today we primarily roast on a 75lb San Franciscan, which is considered moderately sized, but we also have a 25lb and 2lb. You can think of a small-scale roaster like a yacht and a large-scale roaster like a cruise-liner, in terms of stability and manoeuvrability. Smaller roasters have the flexibility to experiment with different roasting profiles and pull off tricky microlot roast profiles, which offers a more tailored and artisanal product. Large-scale roasters can achieve consistent roasting profiles across batches, reducing variability and ensuring a uniform product for customers. We tend to roast our high-end microlots, like Kona Geisha, on our smaller roasters, and our wholesale and café-focused Hawaiian blends, like Hawaiian Harmony, on our larger roaster for uniformity.

Some consumers have started roasting their own coffee at home to experiment with flavours and freshness. What do you think is the future of this emerging market sector?

Not necessarily new. Home roasters have been around for 30 years or more. The consumers that are roasting at home today are the same DIYers that are learning to make their own breads and beers and shopping at farmers markets.

Is it cost-effective to offer a variety of different coffee blends?

Blends aren’t always more cost-effective, but they do provide roasters with the flexibility to adjust the components when the season, supply and quality changes. It’s common for blends to start with a base, somewhat neutral, moderately-to-high quality coffee that originates from large, consistent farms. The second component might have denser flavours and contribute a syrupy body or mouthfeel. The third coffee serves as a highlight. It might be a natural process with strong fruit flavours or high, pleasant acidity.

What sustainability accreditations best demonstrate a commitment to ethical sourcing?

Although speciality coffee and direct trade lack a specific accreditation, we advocate and practice both over accreditations, since many have fallen short from their original intent.

Speciality coffee takes a whole-systems approach to economic, environmental and agricultural wellbeing, because we as an industry have learned that sustainability is rarely black and white. The result is better care of our land, living wages for our workers and remarkable coffee experiences for coffee lovers. Although there is no specific certification for speciality coffee, a coffee must score at least 80 points in a cupping evaluation by a certified Q Grader and be free from defects like mould to qualify as speciality grade.

In our experience within the local and global coffee community, farmers who want to achieve speciality-grade take better care of their land, have updated infrastructure and pay farm workers a premium to harvest or sort ripe coffee cherry.

This holistic, relationship-based approach to producing and purchasing coffee ties premiums to quality, differentiation, innovation and sustainability. Great care is taken throughout the farm-to-cup process to create incredible coffee experiences – from terroir to variety and roasting expertise.

How does the source of single-origin (SO) coffee influence its flavour, given the increasing demand for it?

One of the reasons for farmers to grow and promote single origin coffees is to highlight nuance, terroir and flavour. So the importance of an SO in having a distinctive flavour can’t be overstated. SO coffees are sourced from a specific region, farm or even a single lot, meaning the terroir – climate, soil and altitude – shines through. In combination with specific processing methods, SO coffees are complex and nuanced compared to blends, which are developed for consistency. For example, an SO coffee from the Ka’u region in Hawaii might offer a profile with deep flavours of pineapple and jasmine, while one from the Kona region could present chocolate and stone fruit notes.

By focusing on beans from a single origin, roasters can highlight the inherent qualities of that coffee without the influence of other beans. This purity allows coffee lovers to experience the essence of a particular region’s coffee, undiluted by other flavours.

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