3 Ways to Freeze Coffee
Updated: Nov 16, 2020
I have been freezing coffee since 2017; in order to slow down the aging process, lock in that 'ideal' age after roasting and to enhance the sweetness and texture in the cup.
The first method is vacuum sealing single doses of rare and expensive coffees, then freezing them in a domestic freezer (at -20 oC / -68 oF) to preserve their unique qualities and flavours. I really like the idea and convenience of frozen doses, all dialed in with an exact recipe; ready for the customer to enjoy.
Once dialed in, that's it! There is no need to change the recipe or re-dial - provided the grind size and preparation is the same (going straight from the freezer to the grinder) every time. The results should be the same; delicious!
The only issue is vacuum sealing can be very tedious and labour intensive. I'm always on the lookout for more efficient and productive methods in coffee, especially when it comes to freezing.
The first time I saw a Barista use test tubes to store single doses of coffee was Kapo Chiu (@kapocph) at the World Barista Championship 2017.
Kapo's routine was focused on Gesha Village and the Geisha 1931 varietal; originally discovered in the Gori Gesha forest of Ethiopia in the 1930s. (If you haven't seen this routine I highly recommended checking it out: https://www.youtube.com/watch?v=p52JvF_4lzE )
The second method:
The first time I saw a Barista use these tubes to freeze coffee was Matt Lewin (@matthew_lewin) at WBC 2019. Matt's routine was a customer focused experience; taking the customer on a journey to what coffee can be.
My take away from that routine is that test tubes are a fun, sustainable and efficient method for freezing; allowing the Barista to focus purely on the customers experience.
In June 2020, I started freezing coffee in test tubes.
After tasting coffee that has been frozen in tubes everyday for the last 6 months, I believe freezing coffee with this method is a great option for sustainable freezing and super tasty Espresso.
The third method:
To save costs in the cafe and for short term freezing, the original 1 way valve bag can also be used. I highly recommend pushing any air out the bag and using tape to seal the 1 way valve closed: this is to stop moisture and other elements entering the bag; preserving aroma and flavour.
Any air left in the bag can have a negative impact on preservation and flavour.
The aroma of coffee sets up expectations.
Blind tasting Espressos side by side: the same coffee, same roast date and grind size. With different amounts of coffee dosed into test tubes and frozen for 3 months.
Before tasting and smelling the aroma, I noticed a trend in sweet stone fruit aromatics and a direct correlation to the sweetness and high quality flavours in the cup.
The coffee used for this experiment is: Ethiopia, Guji 005, Washed, Heirloom varietal
At 20.8g in the tube (20.5g in the basket): the aroma was flat: Yellow nectarine, black tea and cocoa, with a low quality black tea finish.
At 21.3g in the tube (20.5g in the basket): the aroma was sweet (like dried apricots). Fresh apricots, white nectarine, pear, earl grey finish.
There is still more testing to do, but I have noticed a trend of tasty espresso with as little headspace as possible before freezing.
Aroma sets up expectations and influences the taste experience.
Experimenting with Argon Gas:
Argon gas is widely used in the wine industry, to create a protective layer in the bottle, preventing oxidation and extending shelf life.
Tasting side by side, the same coffee (Colombia, La Fantasia, CM Washed, Castillo roasted by ONA Coffee), half in test tubes and the other half sealed in tubes with argon.
Tasting blind, at the same drinking temperature, using the WBC scoresheet and putting all the results into a spreadsheet.
Both roasted this year (2020), 15th of March (stored in the original packaging with a 1 way valve) and frozen in 20g doses on the 4th of June.
*a 20g dose does create some headspace in the tube, take note of this for later.
The tubes not sealed with argon, I experienced a higher intensity (not higher quality) of acidity, higher intensity of bitterness and a low sweetness: Orange peel, underripe black berry, low quality black tea.
The tubes sealed with argon, consistently I experienced in the cup, a higher quality acidity and clearer flavours.
A medium acidity, medium sweetness and a medium to low bitterness:
Mandarin, black currant, toffee and an earl grey finish.
𝗪𝐡𝐚𝐭 𝐝𝐢𝐝 𝐈 𝐥𝐞𝐚𝐫𝐧?
I highly recommend using 21-21.5g for Espresso and 21.5-22g (if you can fit it in!) for Milk Based, any headspace (oxygen) in the tube can have a very negative impact on flavour and shelf life.
Argon may be a valuable resource for minimising headspace and to prevent coffee from oxidising: iced filter, batch brew pots, grinder hoppers, retail coffee, etc: there is still a lot to explore.
Test Tubes for Filter Coffee