Techniques that discover new flavors and aromas
If you love iced coffee, chances are you're already familiar with cold brew and iced espresso. The former is brewed in cool water while the latter simply consists of hot coffee poured over ice. But did you know that there are other creative ways to make an amazing cup of coffee?
In this article, we'll be exploring two unique methods of water extraction: using specialized frozen metal cubes and freezing a portion of the water. Our research was conducted by utilizing data from our colleagues at Perfect Daily Grind - stay tuned to find out more!
What is cold coffee
Today, in coffee shops, cold coffee is prepared in two ways:
- With hot extraction. Hot water permeates the ground coffee, and then an experienced barista delicately cools it with ice. This is how cappuccino, latte or rafs are crafted. The taste of these drinks tends to be slightly astringent and tannic in nature because chlorogenic acid forms during roasting - this transforms into cinchona upon cooling which impacts the flavor profile of every cup prepared!Another cooling option is to put the drink in the refrigerator or let it cool to room temperature. This method is used to prepare ready-made coffee in cans or coffee concentrates.
- Using cold extraction. Cold extraction yields a more intense, full-bodied flavor in cold brewed espresso, cold brew and nitro coffees. This is accomplished by passing cool water through the grounds of coffee beans during brewing. The result is an especially vibrant taste with heightened acidity that makes for a truly remarkable drinking experience.
Cold drinks can be prepared using hot or cold extraction.
Coffee companies and baristas never cease to amaze us with their explorations of new ways to make cold coffee. What if we combine hot and cold extraction, they ask? How would that affect the flavor properties in a cup? It's this type of experimentation that leads them closer to delivering the ultimate coffee experience!
Through experimentation, we have been able to introduce a whole new range of coffee drinks with unique flavors. In the early 2000s, Japanese-style cold brew entered the market and in 2021 extract cooling using metal cubes has become popular. What makes these two varieties of cold coffee special? Read on to find out!
Japanese coffee: a combination of hot extraction and ice
Before the 21st century, Japanese iced coffee was a hidden gem only known within Japan since the 1960s. Nowadays, its growing popularity in Europe and America has made it one of the most sought-after drinks around!
For a scrumptious cup of Japanese coffee, you'll need either Hario V60 or Kalita Wave filter. The ratio of ground coffee and water should be similar to what's used for regular hot filter coffee - 15g per 250ml of water. Half the amount is frozen while some ice goes into the server before serving. Heat up the remaining liquid and pour it over your finely-grounded beans to prepare an exquisite cuppa!
According to Matteo D’Ottavio, UK Brewers Cup 2020 champion and barista at WatchHouse London - “Most of the soluble compounds in coffee are extracted during the initial brewing process, resulting in a concentrated drink that is rebalanced with ice. By doing so, we can appreciate brighter and cleaner flavor profiles as well as delicately emphasizing distinct notes from its roasting or genetics. We discover all these amazing nuances by rapidly cooling this hot beverage!
A funnel and a standard filter coffee recipe are used to make a flash brew, but ice is placed in the server
For a perfect drink, it is essential to measure the ingredients with accuracy. Matteo D'Ottavio's recipe calls for 1 part coffee and 17 parts water, 65% of that being hot and 35% cold in the form of ice cubes. Accuracy here is paramount - if you pour by eye instead of weighing, your beverage may lack balance.
“For flash brews, I recommend choosing coffees with high acidity, fruity, floral notes, or chocolate and nutty notes. It is better to grind finer than usual, as less water passes through the coffee,” says Matteo.
To make two cups of Japanese coffee you will need:
- 30 g finely ground coffee
- 325 ml of water at a temperature of 90-96 ° C,
- 175 g ice.
To perfect the art of making a delicious cup of coffee, begin by placing ice into a teapot or other suitable container. Once ready, place a funnel on top and slowly pour in hot water over your ground beans for around two minutes. With this precise method you will be left with an aromatic cup that is sure to tantalize your taste buds!
Baristas have grown increasingly intrigued by this unique preparation method, which yields a cup of coffee that is enriched with flavor and complexity. “Cooking your coffee in hot water reveals nuances you would otherwise miss out on if using cold," explains Lisa-Laura Verkhost, Coffee Manager at GAIL Bakery in London.
Many baristas are more willing to make standard iced coffees due to the seemingly labor intensive flash brew.
Although the Japanese iced coffee recipe is relatively straightforward, it remains a rarity in specialty cafes. To many baristas, flash brewing appears to be more work-intensive than conventional espresso or cold brew based beverages for making iced drinks.
Despite this, not everyone agrees. Lisa-Laura's opinion is that it's more cost effective and efficient to make Japanese iced coffee due to the shorter wait time compared to cold brews, as well as its space saving potential for ice storage versus multiple bottles of cold brew.
Instant cooling with metal cubes
When hot espresso is poured into a cup, some of its delightful aroma flees with it. Yet, we can stop this from occurring and achieve an even more tantalizing taste by taking the necessary steps.
In 2021, World Barista Championship winner Hugh Kelly proposed the revolutionary concept of 'extractive cooling' in his keynote. A unique type of chilled brewing system, extractive cooling utilizes frozen metal cubes to cool down espresso that has already gone through a traditional hot extraction process before it is poured into the cup. With this method of cold extraction, drinks can now be served at their optimal temperature with ease and convenience.
In a collaborative effort between Hugh Kelly (ZHAW) and researchers from Zurich University of Applied Sciences, the extract cooling method was created.
Hugh Kelly used frozen metal cubes in his performance. © youtube.com
From 2017 to 2020, scientists and baristas worked together to uncover the relation between water temperature and aroma compounds in espresso extraction. Astonishingly, their research unveiled that heating certain compounds creates a loss of flavor. Furthermore, they found that up to 12g of espresso exhibits an exceptional concentration of aromatic substances, however once it gets hot these elements start vanishing into thin air.
Scientists discovered that this process could be prevented by cooling the coffee, so they started researching techniques to reduce its temperature. They were reminded of Berg Wu's winning performance at the 2016 Barista Championship when he submerged his portafilters in ice before making espresso. This approach enabled more acidity and floral notes in the beverage.
Despite their efforts, the researchers needed an additional solution for proper cooling. In response, they designed special cubes that rapidly lower the temperature of 12 g of coffee and stop steam from forming to keep all those incredible aromatic compounds in place.
Scientific tests have revealed that the use of metal cubes can save up to 40% more volatile compounds, resulting in an invigorating and intense flavor profile for chilled coffee. Not only that, it also enhances its sweetness!
For the first time, eugeniodis presented a groundbreaking way of making coffee using frozen metal cubes. This species is thought to be at the origin of Arabica and it has significantly less caffeine as well as low acidity. After testing this method on various varieties of Arabica, incredible results were seen - proving its remarkable potential!
Although the researchers are confident in this cooling technology's potential, at present it is not suitable for coffee houses. The cubes must be frozen for a long period of time before creating a beverage and require an appropriate area to store them collectively - both needs which necessitate additional investment and space expansion.
Summary
From iced lattes to cold brews, coffee houses are always experimenting with innovative flavor combinations for the perfect pick-me-up. Baristas and scientists alike never cease in their pursuit of new ways to tantalize your taste buds.
Refresh your senses with Japanese iced coffee, a variation of an already existing brewing method. Also known as flash brew, this coffee utilizes finer grinds and ice for a distinctively clean taste profile filled with bright acidity and unique lot-specific descriptors. Enjoy the perfect cup of cold brew anytime!
With the innovative frozen cube refrigeration technique, coffee drinkers can savor an entirely different taste profile. Thanks to this method, 10-40% more flavor compounds remain in the cup which results in brighter and richer aromas and flavors that boost sweetness!