Brew Temperature and its Effects on Espresso

Posted by Matthew Patrick McLauchlan on

Brew ratio_1

One of the topics we explore in depth in our Advanced Barista Skills class at the Australian Barista Academy is brew water temperature and its effect on espresso taste and extraction.

Brew temp is an easily accessible brew parameter with the right espresso machine, but is not something that all café operations chose to alter as part of their morning dial in. Conversely there are plenty of cafes using brew temperature for everything from regulating extraction yield, to overcoming issues with machine and grinder temperature as their workload increases. To bridge the gap and provide some info for new and experienced baristas alike, I’ve prepared some objective testing and solid numbers to digest.

Brew temperature: things people say

It has been observed using a standardised recipe and solid brewing technique that brewing hotter will result in higher extraction yields (more content removed over time) while brewing colder will extract content at a slower rate (less content removed over time). Taste wise, hotter temps result in increased body and sweetness (with a greater chance of astringency and bitterness), while cooler temps emphasise less bitterness, body and sweetness (resulting in a sour, bright shot).

Baristas who are savvy with brew temp modification might make some of the following suggestions:

  • Lowering the brew temp will enhance acidity in coffee/raising the brew temp will decrease acidity in coffee.
  • As the grinder heats up, the ground espresso coffee tend to become more soluble, and extraction yields can increase. Lowering the brew temp is a way to counter this.
  • Don’t change your grind to affect your extraction yield; change your brew temp
  • Increasing the temperature can be used to increase the extraction yield of a slow, dripping shot.
  • Higher temps can be used to compensate for an underdeveloped roast while lower temps can be used to overcome the high solubility of an overdeveloped roast.

These suggestions guide practice in many commercial cafes. There is probably a mixture of truth and half-truth among them, and maybe even some outright heresy, but it would certainly be nice to have more data to back it up. If you stay tuned for a follow up article you’ll get exactly that — I’ll be using some nifty equipment to test the effects of puck depth, density, and brew temp. For today’s article I wanted to answer a simpler question — what does brew temperature do to extraction yield and flavour?

The effect of brew temperature on extraction yield

If you need a quick catch-up on extraction yield and what it is, check out our previous article on VST baskets here.

To fully test the effects of brew temp on extraction yield, I set up the following test:

  • 40 x 22g espresso shots were ground en masse and allowed to cool to room temp.
  • The espresso shots were prepared using a standardised recipe: 22g dose, 46-48g beverage, ~29 seconds shot time. The preparation method used was a stockfleth distribution followed by a single collapse on the bench and a super firm tamp.
  • A single grouphead and handle were used.
  • Ten shots were poured at each brew temperature (92, 94, 96 & 98 °C) Espresso was prepared in groups of 10 – first at 92, then 94, 96 and 98.
  • Shot time and beverage weight were recorded for each extraction.
  • A sample of each coffee was immediately removed and sealed (in a pipette) to prevent sample evaporation.
  • Each sample was filtered and TDS readings were taken.
  • Extraction yield was calculated and recorded.
  • Samples were set aside for tasting.

The raw data

To remove the outliers, I sorted each temperature category by extraction yield and removed the two highest and lowest data points. This reduced the sample size, but removed outliers resulting from inconsistent extraction behaviour.

Tables 1-4 summarise the data for each extraction temperature, and Figure 1 puts it all together for you.


Table 1 - 92°C

Cup Temperature (°C) Dose (g) Beverage (g) Time (sec) TDS Yeild %
1 92 22 48.3 29 8.41 18.4
2 92 22 46.6 28 8.7 18.4
3 92 22 48.2 29 8.53 18.8
4 92 22 46.2 30 9.26 19.3
5 92 22 47.1 30 9 19.3
6 92 22 47.1 32 9.11 19.5
Averages     46.5 30.3 9.2 19.38

Table 2 - 94°C

Cup Temperature (°C) Dose (g) Beverage (g) Time (sec) TDS Yeild %
1 94 22 46.7 29 9.09 19.3
2 94 22 46.2 30 9.22 19.3
3 94 22 47.1 32 9.01 19.3
4 94 22 46 31 9.28 19.4
5 94 22 45.4 30 9.39 19.4
6 94 22 47.8 30 9.03 19.5
Averages     46.5 30.3 9.2 19.38

Table 3 - 96°C

Cup Temperature (°C) Dose (g) Beverage (g) Time (g) TDS Yeild %
1 96 22 44.8 29 9.43 19.1
2 96 22 45 29 9.43 19.2
3 96 22 46.1 30 9.24 19.3
4 96 22 45 29 9.49 19.4
5 96 22 46.2 30 9.41 19.7
6 96 22 47.2 30 9.23 19.7
Averages     45.7 29.5 9.4 19.40

Table 4 - 98°C

Cup Temperature (°C) Dose (g) Beverage (g) Time (sec) TDS Yeild %
1 98 22 46 28 9.25 19.2
2 98 22 47.2 29 9 19.3
3 98 22 47 30 9.08 19.4
4 98 22 48 31 8.89 19.4
5 98 22 48.9 31 9.03 20.0
6 98 22 48.6 30 9.03 20.1
Averages     45.7 29.8 9.1 19.57

The Results

Brew ratio_2

You can see from these results, a nice consistent trend! Lower brew temperatures produced a lower extraction yield, whereas higher brew temperatures produced a higher extraction yield. With a much larger sample size, we might expect to see a smoother line. What’s most surprising from this data is the relatively small difference in extraction yield a 6°C temperature change makes! The total difference was just over half a percent yield from 92 to 98. Even more interesting is just how radically different the cups tasted, despite the relatively small difference in extraction yield.

The effect of brew temperature on taste

Despite the small differences in extraction yield, the four temperature groups tasted radically different. I blind tested this with our staff and the response was exactly what theory predicts:

  • the lowest temp cups had lower body, sweetness and bitterness but higher acidity.
  • the highest temp cups had lots of body, sweetness, bitterness, medium acid… and a strange powdery mouthfeel .
  • the two mid temps were balanced, with high levels of sweetness, balanced acid, low bitterness and good body.

Does this mean our tasters were detecting the tiniest differences in extraction yield, or is it something to do with the balance of constituents removed from the coffee? Maybe both? I’m going to go with maybe both, and if you read on you’ll see why.

The perceived flavour changes which result from altered brew temperature are in agreement with data from ‘The Coffee Brewing Handbook’ (Ted Lingle, SCAA). Rather than reprinting the whole section on temperature changes from the handbook (I’d love to), Figure 2 is a quick graph I made from data in the book showing how the flavour components of the brew change as the extraction temperature changes (74, 94 and 100 °C).

Brew ratio_3

There are a few trends you can see in this graph:

  • The amount of citric acid extracted falls as the temperature increases from 94 to 100°C.
  • The amount of malic acid in the cup is lowest at 94°C.
  • Extraction is optimised at 94°C (sucrose/sugar extraction is at its peak), with a large increase up from 74°C.

Even with this snippet of data, you can see the huge effect brew temperature has on constituent balance*. If this isn't a great explanation for the taste differences in our cups, then the other route to explore the huge effect on taste which we get from very small differences in extraction yield.

Conclusions

If you put it together, this data clearly demonstrates two things — higher brewing temps lead to higher extraction yields, increased sweetness, bitterness and body while slightly reducing acidity. Lower temps result in lower extraction yields; have less body, sweetness and bitterness and more pronounced acidity. Although the yield differences are small, the cupping results are huge, leading me to the conclusion that there’s a little more at play in terms of what temperature does to our cup profile than to simply increase or reduce overall extraction yield — the changes to the extraction of each flavour component are larger than the overall change in extraction.

This round of testing wasn’t thorough enough to answer some of the most burning questions on the topic of brew temp. One thing that stands out is the limited information gained from the use of a single espresso recipe and its resulting flow rate — would a faster flow rate provide a wider range of extraction yields? This is something I’m very keen to explore. Stay tuned for an upcoming article in which we further explore the effects of temperature across a range of grind profiles, as well as the effect your espresso flow rate has on your ability to thoroughly extract coffee (and how temp can help in that regard).

*the testing from Lingle’s book was conducted with large volumes of filter coffee, not espresso. Still, I believe the effects observed in my testing on espresso are due to a similar effect of creating a different balance of constituents depending on the brewing temperature.

References
Ted Lingle. The Coffee Brewing Handbook (Specialty Coffee Association Of America Handbook Series, Second Edition). SCAA, 1996.

This article was originally published on the Five Senses Coffee website: Brew Temperature and it's Effects on Espresso.

Read more →

Singapore Latte Art and Inaugural Brewers Cup

Posted by Matthew Patrick McLauchlan on

Latte Brewers_1

Fresh off the Singapore National Barista Championship held in late January, comes Cafe Asia – Southeast Asia's biggest coffee and tea exposition. This event brings together the coffee and tea communities, and the likeminded folk within the hospitality industry. It was sight to behold with all the various high end and innovative equipment on show.

Café Asia was also host to two main events for the Singapore Coffee Community, the Singapore Latte Art Competition and the inaugural Singapore Brewers Cup.

Even through it was the very first ever Brewers Cup, the level of competition and quality of coffee on show was impressive to say the least. Not only was there a variety of ninety plus coffee and brew devices on showcase, but the each competitor brought with them a very professional presence with a touch of their own individualistic flair. Andrea Tan from A.R.C Coffee blew us away with a brilliant performance belying her young age with a very tasty coffee to boot.

Our very own Lucky Salvador brought his A-Game to the table as he used a Kalita Wave, running the a natural processed La Pastora, Costa Rica from Mainor Esquival's mill. Lucky created an amazing cup which packed a punch, with a very polished and personable performance which helped him claim 3rd place in the Brewer's Cup.

In the Latte Art Competition, Jervis Tan of Kinsmen Coffee came out tops with his clean lines and symmetry; with a signature pour of a peacock comprising of all latte art techniques on show. Credit goes out to Nijo Neo from Common Man Coffee for giving his all in what was a very skilled group of competitors in the 1st round.

We would like to again send out our congratulations to the winners, Andrea Tan of A.R.C Coffee (Singapore Brewers Cup) and Jervis Tan of Kinsmen Coffee (Singapore Latte Art Championship) the best of luck at the World Championships held later in Gothenburg, Sweden.

OFFICIAL WINNERS

Singapore Brewers Cup
1st: Andrea Tan from A.R.C Coffee
2nd: Hidayat from Gentleman's Coffee
3rd: Lucky Salvador from Common Man Coffee Roasters

Singapore Latte Art Competition
1st: Jervis Tan from Kinsmen Coffee
2nd: Joefel Manlod from House of Robert Timm's
3rd: Shyan Wei from A.R.C Coffee

Latte Brewers_2

Latte Brewers_3

Read more →

Nude Seafood

Posted by Matthew Patrick McLauchlan on

Nude_1

Dining in the Central Business District in Singapore has never been easy. Coffee places rarely serve either great food or food that’s easy on the wallet. So when two former management consultants, Whey Han and Jun Chen, both with no prior food and beverage experience, decided to go into a venture together, they wanted to do something different. Their lack of experience in the F&B industry meant they genuinely brought a fresh perspective to the creation of NUDE seafood; the name reflects that the seafood is both NUtritious and DElicious. In essence, they wanted to make real food fast and put value back on the plate. As a result, the whole operation was designed to be as efficient as possible, cutting down on labour and wastage. You get high quality food, but it’s served with a speed more usually associated with a fast food restaurant – and all this at affordable prices! The menu is short and simple, and includes my all-time favourite dish, Norwegian hickory-smoked Salmon ($16), which comprises sushi-grade salmon accompanied by savoury, smoked beetroot cubes and forgotten grains. Other options include herb-grilled King Prawns ($16) and miso-grilled Seabass with quinoa ($19). There are also some chilled options such as Aburi Salmon belly with soba ($13) and Chilean Bass with somen, mushrooms, corn and egg ($16).

Jun Chen believes that food is about making people happy – and to do that, you need a happy team. By incorporating aspects of the corporate culture from Google and Apple into his team at NUDE, he is setting the bar high, hiring people with capabilities, passion, character and the ability to fit into NUDE’s culture. He’s also worked hard at creating an environment whereby team members bring out the best in each other; as a result, magic happens. The team at NUDE keep their focus on their core product (seafood), so they seek out partners to provide the best of everything else. That’s where Common Man Coffee Roasters comes in. A 2 group Synesso sits at the end of the bar counter serving their custom blend from CMCR which pairs perfectly with the seafood dishes. Even their ceramics are made by local artists which brings a certain character to the place.

It’s now been open for four months and NUDE seafood has already gained a regular following. It’s hardly possible to find a seat during lunch hour when a queue snakes all the way to the door. However, the service is fast and efficient and the line moves very quickly.

The CBD crowd will be happy to hear that a team of talented young chefs with experience in renowned restaurants like Les Amis are planning to create a separate dinner menu for those working late in the CBD.

NUDE Seafood
Marina Bay Financial Centre Tower 3
01-02, Singapore 018982
(Marina MRT Station – Downdown line, or 15 min walk from Raffles Place MRT)

Opening Hours
8am - 8pm

facebook.com/pages/NUDE-Seafood
instagram.com/nudeseafood

Nude_2

Nude_3

Nude_4

Nude_5

Read more →

The Clueless Goat

Posted by Matthew Patrick McLauchlan on

Clueless Goat

New kid on the caffeine block, The Clueless Goat, takes maximum advantage of a clever location just a hop, skip and a jump from the Novena MRT. The cafe itself is a stylish and unpretentious space. Plenty of glass and a communal table give it a welcoming and relaxed vibe, with the warm glow from the Edison light bulbs playfully arranged to make the cafe well lit and inviting.

The Clueless Goat is the lovechild of experienced F&B operators, Zak and Demelza who have combined their love of great coffee, good food and vibrant art into one beautifully curated space. Zak displays his artistic flair right throughout the venue with illustrations and paintings appearing on walls and menus.

And while the goat may be clueless, this couple are definitely not clueless when it comes to coffee!! They carefully selected the 22 Martin Road blend and a 2 group Synesso Cyncra to ensure that the coffee is consistently excellent — and it is quickly winning approval from the local community.

With a menu that provides all day brunch at really affordable prices, it is easy to see how this place has already won the hearts of some savvy locals who have quickly made it their regular haunt. An early house favourite is the Ranchers Eggs composed of perfectly poached eggs, smashed avocado, fresh salsa and shaved Parmesan on multigrain toast. Delicious!!

So if you’re in the Novena neighbourhood, walk straight past the big green mermaid and seek out The Clueless Goat, a great new addition to the Singapore cafe scene.

The Clueless Goat
189 Thomson Road
Singapore

Opening hours
Monday: Closed
Tuesday - Thursday: 8am-6pm
Friday: 8am-10:30pm
Saturday: 9am-10:30pm
Sunday: 9am-6pm

facebook.com/thecluelessgoat
instagram.com/thecluelessgoat

Read more →

SNBC 2015 and the Growing Specialty Coffee Industry

Posted by Matthew Patrick McLauchlan on

SNBC 2015

Although it has been over a month now since Singapore held their 2015 Nation Barista Championships, it is never too late to celebrate the success of all the competitors and raise a glass (really a coffee cup) to the growing specialty coffee industry in Singapore.

Back in January, under the towering formation of the Marina Bay Sands, 16 dedicated Baristas took center stage. Each competitor undoubtedly spent months in preparation for his or her 15 minutes in the spotlight. Within these months, a specific coffee or coffees were meticulously chosen to be best represented by this competitor. With hours upon hours of routine rehearsal and revisions to one’s speech, there is no quicker way for a Barista to gain invaluable knowledge & experience then to have the fortitude to compete (no offenses to those Scott Rao fans out there).

This dedication and growth curve was easily on display for the two days of competition. With an inspiringly large audience that helped to cheer on the first day of great performances, each competitor were equally scrutinized by calibrated judges in an effort to find the top 6 challengers for the final day. Being fortunate to help judge the past two Singapore National Barista Championships (SNBC), it was easy to see the caliber of performances increase to a level on par with industry power houses such as Japan, Hong Kong and Australia. This first day of competition brought great excitement to the Common Man Team, as Xin Loke made it into the top 6 finalists in hopes of recapturing her crown.

The following day an even bigger supportive and passionate crowd filled the void of the convention halls, in-which they stood witness to Singapore’s top Baristas battle out the finals. Each competitor held nothing back in an effort to be crowned the 2015 SNBC champion. With amazing coffees on display (often from Central America or East Africa) and the previous day’s jitters gone, each of the competitors routines were a formidable attempt to take the crown. In the end, after the suspense of a careful judges deliberation, John Ryan Ting (a veteran of a previous win in early 2000s and recently a WBC judge) brought all his experience to the table to find a second victory. With tears in our eyes due to the loss of our own, our hats were off in celebration of John’s worthy win.

Congratulations to John Ting and to all the competitors who courageously put their skills on display in an effort to continually push our industry forward. We at Common Man will no doubt continue to support such events, in joint effort with our industry colleagues, to help inspire and challenge passionate coffee folks to elevate their knowledge and experience through competition.

Now with your coffee cup held high, here’s to 2016 SNBC!

For more information on upcoming World Coffee Events in Singapore and a transparent look at the point spread between the top 6 competitors of this years 2015 SNBC please view Singapore Coffee.

Read more →