What is the optimal quantity of coffee to purchase ?
Author: Head Roaster Date Posted:1 June 2016
These days, there seems to be a set of rules for any dinner party - don't talk about religion, politics or coffee !
Yes, it seems everyone knows a coffee expert - that person who bangs on about everything coffee like a walking encyclopaedia - I should know, I'm one of them
The side effect of having so many coffee experts in the world is the vast amounts of mis-information that circulates the internet - further fuelling and substantiating the evidence-based knowledge of these so-called experts - they have read it somewhere, therefore it must be true.
There are 2 important pieces of information every coffee consumer needs to understand - never freeze roasted coffee beans and fresh roasted coffee is only at it's peak for just 30 days (some coffees can last longer - see below).
In articles published elsewhere, I've argued for years and years against freezing of roasted coffee beans. Of course, there are always the contrarians who take extreme pleasure in debating the exact opposite. Who are you going to trust - the one a day coffee drinker who is used to consuming the same, average quality coffee every day that swears by his rotine of freezing and thawing the beans or the person with 35 years experience who tests hundreds of coffees each week.
Rather than bore the bejesus out of everyone with technical mumbo-jumbo just take it as a given from someone who has run numerous experiments over many years - please don't freeze your coffee unless you live in a constantly hot environment (over 30 deg C) and it costs your a fortune in shipping expenses to receive regular fresh roasted coffee.
The other key piece of important information is for how long will a coffee remain good and it's the focal point of this article so that you can do some basic calculations on average consumption to determine how much coffee to purchase.
A common mantra bandied around by coffee experts is the simple rule of 3's
ground coffee - 3 minutes, roasted coffee - 3 weeks, raw coffee - 3 years.
Now, let's take a more precise look at those rules of 3.
Raw coffees may last literally forever, but in Australia's harsh climate, 12 months can strip 25% or more from the quality of a high grade raw coffee. After 3 years, most raw coffees are dried out and present a severe fire risk if roasted.
Now, in terms of ground coffee - everyone knows the delightful sensation caused by the process of grinding fresh roasted coffee beans.
When the beans are ground, particles explode in aromatic symphony. It's this initial contact with oxygen that creates the high levels of aroma as you have in effect broken the cell structure of a bean into hundreds of tiny particles that are exposed to rich levels of oxygen - therefore initiating the process of rapid staling.
The smaller the particle, the faster the staling and hence the short timeframe applies.
In realistic terms, ground coffee has around 15 minutes of oxygen exposure, although I certainly don't use ground coffee in my espresso if it's been sitting for more than 5 minutes.
It really depends upon your brew method for the use of the ground coffee.
Some methods such as espresso are highly sensitive to stale ground coffee, which is why good cafes will always fresh grind on demand for each order of beverage. Stale ground coffee (like what the supermarkets offer) will result in a lack of crema, body, aroma, flavour and sweetness in espresso beverages.
Other brew methods such as percolator and plunger may be less affected by oxidized ground coffee as the contact time for the water with the ground coffee is much longer.
For roasted whole bean coffee, the period of time it will remain optimal depends upon some variables -
- roast depth - darker roasted coffee ages faster.
- Ambient storage temperature - this includes the temperatures that the roasted coffee beans may have been exposed to during transit. Higher ambient temperature dramatically accelerate the oxydization or can even lead to low-level baking of the roasted coffee beans resulting in a degraded quality.
- How the coffee is stored once the pack is opened. Zip locks are nonsense - they don't provide an adequate freshness barrier as the essential compounds of fresh roasted coffee beans will actually "leach" through the plastics used in zip locks via a process called effusion (same as why you can't put oil in a plastic bag). Storing the contents of an opened pack of coffee in a metal, ceramic or glass jar away from sunlight and heat, but not in the fridge or freezer is better. It is also possible to carefully fold over the corner of an opened coffee bag many times and with a bull-clip that is often used for holding large numbers of pages together.
- Certain types of coffee are capable of lasting longer in the optimal peak period than others. Monsoon Malabar is one such coffee that can take up to 2 or more weeks to reach it's peak and then hold a decent quality level for more than 6 weeks. Sumatrans, when roasted well can also take longer to develop and hold a quality level over more than a month.
For the majority of roasted whole bean coffees, the peak periods are typically start from around 5 to 12 days of the roast date and run until around 30 days from the roast date. Some coffees may start to degrade from 21 days.
Those of you confused as to why the period starts many days after roasting - it's because the coffee continues to develop for a period of time after roasting, it's unstable, gassy and the flavour has not fully reached it's peak and stabilised. Some coffees need up to 12 days to develop post roast.
Again, this really depends upon ambient temperatures and storage integrity.
The other point is that many people have varying ideas on what constitutes quality - some are less fussy, being happy to order in bulk and drink coffee for a couple of months, whilst others are more particular and demand coffee that is less than 7 days old.
Either way, we cater for all types as our product is super fresh when it leaves our roastery - allowing you to experience the coffee at it's peak.
You can also read our article: Light, Medium and Dark roasting styles.