Carbon Dioxide & Coffee
Is it an undesirable carbonation
July 2014
Contention:
Which method of storage benefits medium roast coffee, given that their maximal
consumable age is of 23 days?
This experiment is to validate that coffee is not undesirable when at its
maximal age for consumption given storage is suitable, as decided by the team at De Groot Coffee Co.
Does CO2 reabsorption within a sealed, valve-less environment speed up the
staling process once the bucket is open, or taint the coffee? (for this length
of time specified)
Does coffee stored in a one way valved package taste superior to the
alternate methods considered? For all the bloody obvious reasons...
Does a completely open vessel, where CO2 and O2 can diffuse on an
unrestrained concentration gradient, reach an undesirable staleness by the 23
days?
Does allowing 72 hours post roast, degas time in
an open environment before sealing airtight the bucket, create a better environment
for the coffee, as major CO2 has transpired, perhaps reducing the reabsorption
of CO2 over the next 21 day period?
The Subjects
Tasting each of the following samples at 23 days of storage to assess the
quality of the cup and how it reflects its storage environment.
S1
= Airtight container, (no valve)
S2 = Non airtight container, lid slightly ajar for entire period
S3 = Open container
S4 = control (age controlled) non aged beans in Airtight container (1
week)
S5 = 1 way Valved bag
S6 = Airtight container packed 5 days post roasting, allowing time to degas before
sealing.
Hypothesis:
S1 Airtight will best perform. The inability for O2 to
penetrate the bean being the advantage. However, S1 could be prone to
staling faster than others as the high CO2 levels within the bean play havoc.
S5 Valved and S2 Non airight I expect quite similar results for the
length of such an exercise. S5 Valved losing
more CO2 than S1 Airtight, but for the length of experiment, I doubt any taste influence
will be detrimentally detectable. S3 Open will be a palatable
experience, but perhaps a notch below what I expect from S2 Non airtight.
S3 being such a small mass in a very large breathing volume.
Results: Cupped
Cup 1 = S5 Valved bag.
Poor results after Break. Flat.
Cup 2 = S3 Open container.
Similar to S5. Flat all the way
through however.
Cup 3 = S4 Control RD
30/7. As predicted, most outstanding on the table.
Cup 4 = S1 Airtight. Very
surprising how this coffee held the field in wet & dry aromas for
intensity. Notes revealing 'stock like' & 'meaty'. Terrible on second &
third passes as the liquid cooled. Least desirable on the table.
Cup 5 = S2 Lid Ajar container.
Third preferred coffee. Lovely, full break & cupped with lovely acidity.
Cup 6 = S6 Airtight (5 days breathing before sealing) container.
Winning coffee after the predicted sample S4 Control. Aromatics not particularly strong, however balanced. A
stable cup throughout the cupping.
Espresso Machine:
Putting the winning S2 Lid Ajar & S6 Airtight
(5 days breathing before sealing) of the aged candidates through the
espresso machine.
The winning coffee S6 Airtight (5 days breathing before sealing)
took the gold in the espresso by far. Most notably the results of the cupping
shone here, where we needed them to as the espresso machine is where truth is
revealed for the majority of our coffee drinkers. The aromatics and crema of S6
Airtight (5 days breathing before sealing) in comparison to S2 Lid Ajar were
astonishingly representative of a healthy espresso bean behaviour alongside a
stale bean. The salty, sweet, viscous espresso of the winning S6 Airtight (5
days breathing before sealing) and its nutty, full, balanced body with
milk. Wonderful surprise. S2 Lid Ajar however finished short, sharp and
terrible. Deceiving in that this coffee did cup relatively well and performed
competitively alongside its rival winner on the Cupping table. The intensity of
the extraction of espresso puts the beans through a very scrutinizing
procession, clarifying further what was revealed on the table initially.
S6 Airtight (5 days
breathing before sealing) & S2
Lid Ajar subjects demonstrated that the breathing element to coffee is imperative. BEST & SECOND BEST coffees respectively.
S1 Airtight completely defied
my prediction of being quite palatable. Completely overly exposed to the
exhaling CO2 of the bean. O2 attack not even playing a role in the staling
process as to its inability to penetrate the bean. SECOND WORST CUP
S3 Open opposing
representation of excessive CO2 exposure, also demonstrating that the abundant
room for CO2 exhalation proved useless; increasing the O2 exposure, causing the
rapid staling. WORST CUP
S5 Valved as the S3 Open
cup, with a hint of vibrancy in acidity (nothing to get excited about) ran
equally WORST CUP
S4 Control (Roast age 5 days) of course WON and blew our
minds. However the control is shunned for the results section as she is a show
off, not meeting the requirements of the Experiment!
Conclusion:
CO2 is the worst enemy for coffee stored for a 23 day period. Stability in
the cup is achieved for this aged bean when the environment allows for EXHALATION of the Co2 and limited supply of O2. The winning result of the experiment S6 Airtight
(5 days breathing before sealing) demonstrates
that the DEGASSING period for coffee before an AIRTIGHT seal for the remainder
of the stored life, will produce better cup quality over all.
