Unlocking the Secrets of Cold Brew
As I stepped into the cozy coffeehouse on that unseasonably warm autumn day, I found myself drawn to the tempting menu, seeking a refreshing respite from the heat. And there it was – the increasingly popular option, the cold brew. Those alluring words, “sweet and smooth,” piqued my curiosity. Were they merely marketing speak, or did they hint at a deeper understanding of the crucial role that sensory attributes play in shaping the coffee-drinking experience?
For those of us in the specialty coffee community, we know that the flavors, body, and aromas that end up in the cup deeply impact consumer behavior, from purchase intent to customer loyalty. Consequently, the management of these sensory attributes – enhancing the desirable and suppressing the undesirable – is becoming increasingly important in a growing and competitive market. And as the share of the cold brew segment continues to rise, it’s clear that the perceived differences between hot-brewed and cold-brewed coffee are worth exploring.
Demystifying the Cold Brew Phenomenon
Some of us may have personal or professional experiences that have shaped our understanding of the sensorial differences between hot-brewed and cold-brewed coffee. Perhaps you’ve even noticed the impact of temperature on other everyday processes, like the way hot water can extract color more quickly when making tie-dye. In the world of coffee, this concept is known as total dissolved solids, and it’s an important factor in understanding the sensory profile of the final brew.
But while our experiences and intuitions can provide valuable insights, business decisions are best supported by substantiated qualitative analysis. That’s where the research team at the UC Davis Coffee Center, led by Dr. Mackenzie Batali, comes in.
Beginning in 2021, Batali and her team embarked on a comprehensive exploration of cold-brew extraction techniques, including temperature, brewing time, and extraction percentage. They meticulously documented the comparative impact of cold brew on the sensory and chemical attributes of coffee, using a variety of specialty roasts and origins.
A Controlled and Systematic Approach
The common belief is that the cold-brew process produces a sweeter, smoother, and less acidic coffee compared to its hot-brewed counterpart. However, these claims were largely based on the extensive personal experience of coffee professionals, rather than a controlled and systematic study.
To address this, the UC Davis team designed a study that aimed to remove as many variables as possible, focusing solely on the impact of brew temperature on the sensorial profile of the coffee. They used a full factorial design, which means they explored three different green coffee origins, three roast levels, and three brewing temperatures – refrigerated, ambient, and hot.
By brewing the samples to equilibrium extraction, where the total dissolved solids (TDS) and extraction yield (EY) stabilized, the researchers sought to ensure that any differences observed could be attributed to the brewing temperature alone or the interaction between the coffee’s origin or roast level and the brewing temperature.
Sensory Insights: The Impact of Temperature
The results of the study were fascinating. While the goal of brewing to equilibrium was to eliminate the impact of extraction yield, the team found that it wasn’t quite that simple. The hot-brewed coffee had the highest equilibrium TDS and EY, followed by the ambient-temperature and refrigerated samples.
This suggests that there may be some molecular components of coffee that do not extract as readily at lower temperatures, even with extended brewing times. Further chemical analysis would be required to identify these components.
Additionally, the researchers found that the cold-brewed coffee consistently had a slightly higher pH, or was less acidic, than the samples brewed with hot water. This aligns with the common perception that cold brew is less acidic, and it’s an area that would benefit from additional exploration.
But the real insights came from the sensory panel’s evaluations. Regardless of the coffee being brewed, the hot-brewed samples were perceived as more bitter, sour, and rubbery, while the cold-brewed coffee was more floral in nature.
Roast Level and Origin Matter
Interestingly, the researchers also found that the roast level and origin of the coffee impacted how its sensory profile was perceived when brewed at different temperatures. For light roast coffees, there were no additional differences beyond those identified based on brew water temperature alone.
However, at the medium roast level, panelists identified more burnt and whiskey flavors in the hot-brewed samples. At the dark roast level, they detected more woody flavor in the refrigerated and ambient-temperature brews.
When looking at the different origins, the team found that panelists identified more burnt flavor in the hot-brewed Ethiopian samples, more fruity flavor in the cold-brewed Ethiopian samples, more woody flavor in the cold-brewed El Salvador samples, and more smoky flavor in the hot-brewed Sumatra samples.
Putting It All Together
These findings suggest that the quality of the coffee itself plays a much more significant role in the final flavor profile than the subtle differences introduced by the brew temperature. In fact, the researchers concluded that the differences in sensory attributes between cold-brewed and hot-brewed coffee, while noticeable, may not be substantial enough to drastically alter a consumer’s preference.
As Batali and her team continue to explore the relationship between brew water temperature and the time required to reach equilibrium extraction, one thing is clear: the choice between cold brew and iced coffee ultimately comes down to personal preference. While there may be some validity to claims that cold brew is less acidic, the coffee you choose to brew will have a more significant impact on the flavor profile in the cup.
Regardless of where you fall on the cold-brew vs. iced-coffee spectrum, this research highlights the complexity of the brewing process and the myriad variables that can influence the sensory experience. As the coffee industry continues to evolve, we can expect to see even more exciting discoveries that shed light on the science behind our favorite beverage.
So, the next time you find yourself faced with the choice between a refreshing cold brew and a classic iced coffee, consider the nuances of the roast, the origin, and the brewing process. And remember, the true joy of coffee lies in the journey of discovery, where each sip offers a new opportunity to explore the sensory science that makes this brew so captivating.
Exploring the World of Coffee Flavors
Speaking of discovery, have you ever wondered what factors contribute to the unique flavor profiles of different coffee origins and roast levels? Let’s dive a little deeper into the world of coffee science and uncover some of the fascinating insights that can help you better understand and appreciate the complexity of this beloved beverage.
One of the key factors that shape a coffee’s flavor profile is the processing method used to prepare the green coffee beans. For example, the honey process used in the El Salvador coffee from the study is known to produce a sweeter, more balanced flavor, while the wet-hulled processing of the Sumatra coffee can result in a more earthy, smoky profile.
The roast level also plays a crucial role in determining the final flavor. As we saw in the UC Davis study, light roast coffees tend to have a more delicate, floral character, while medium and dark roasts can bring out bolder, more intense flavors like burnt, whiskey, and woody notes.
But it’s not just the processing and roasting that matter – the origin of the coffee beans themselves can have a profound impact on the flavor. The Ethiopian coffee in the study, for example, was perceived as more fruity and less smoky when brewed with cold water, compared to its hot-brewed counterpart.
These nuances are what make the world of coffee so endlessly fascinating. And as the specialty coffee industry continues to evolve, we’re likely to see even more exciting discoveries that push the boundaries of what we thought we knew about this beloved beverage.
Embracing the Art of Exploration
Of course, the ultimate test of a coffee’s quality and suitability for a particular brewing method comes down to personal preference. As the researchers at UC Davis concluded, the coffee you choose to brew will have a much more significant impact on the flavor profile than the subtle differences introduced by the brew temperature.
That’s why I encourage you to embrace the art of exploration when it comes to your coffee experience. Don’t be afraid to try different origins, processing methods, and roast levels to discover your personal favorites. And when it comes to the cold brew vs. iced coffee debate, be open to experimenting and finding the approach that best suits your taste buds.
After all, the beauty of coffee lies in its ability to surprise and delight us, to transport us to different corners of the world with a single sip. So, let’s raise our cups and celebrate the sensory science that makes this humble little bean so captivating. Who knows what delightful discoveries await us on the path ahead?
Sips Coffeehouse is always here to support you on your coffee journey, with a wide selection of specialty roasts and a team of passionate baristas ready to guide you through the world of flavor. So, what are you waiting for? Let’s dive in and unlock the secrets of the coffee bean, one sip at a time.