The Manchester Coffee Archive caught my attention as soon as I found out about the project. The Archive freezes samples of roasted coffee to preserve them for later use. Before the pandemic, the Archive hosted tastings of coffee from different years. In this interview, Tom, an archivist, notes that he is drinking a coffee from December 2019.
Interested in coffee freezing and this project, I reached out to the team at the Archive. Tom responded to my interest in learning more about the project and helped answer a few questions on my mind. The interview is below.
For my readers who are not familiar with the Manchester Coffee Archive, could you briefly describe the project and what you hope to accomplish?
Manchester Coffee Archive is a crowd-sourced collection of coffee beans, stored in freezers to preserve their flavours for a long time. We freeze coffee so we can put together themed tasting lineups for anyone that wants to come and taste some nice coffees and meet fellow enthusiasts. We rely on coffee contributions to keep the Archive (which currently holds over 500 coffee samples) going.
What procedures do you follow to prepare a coffee for the archive? Do you use any special equipment?
We only need 12g of each coffee for a tasting but some grinders need a few beans to purge the burrs in between samples, so our standard protocol is to vacuum-seal 26g of every coffee we freeze. The vacuum-sealer we use is just a domestic one from the internet: a good one is generally around £40. We currently make our own small vacuum pouches from 12cm wide vacuum-sealing plastic roll, which I buy online. While I bought the vacuum sealer specifically for coffee, I have since found it is handy for lots of other kitchen-based tasks - a worthwhile investment I would say.
How much work does the project take?
Initially, it was quite a big project to set up. We are a small team (Tom, Mani and Amy) and there was a lot to consider in the early days: each tasting requires a bit of digging through the freezers, but we have it down to a lean process now. The tastings themselves are on hold for now, so all I do these days is pop a sample in the freezer each time I open a new bag. I froze my 236th contribution today. It is just muscle memory at this point.
Freezing coffee at home is a somewhat controversial subject. Under what circumstances do you think a consumer can freeze coffee at home without compromising its integrity?
This is subject to some debate, and I think there is a lot more testing that could be done to narrow down the minimum criteria for successful home freezing. We vacuum-seal our samples because it currently seems to be the best method that is easily accessible, and has a good track record with long-time Coffee Freezers (the people, not the appliances).
It most likely comes down to how long the coffee is being stored for in the freezer: any sealed container will probably be fine for a few weeks, maybe months. But, if you are looking to preserve it for several years it is definitely worth considering how much air is in the packaging and whether there is any chance of air leaking into the container over time
In my opinion, if you are looking to use the coffee within a few months, putting it in a zip-lock bag or a full (no space for excess air) container in the freezer will probably preserve the coffee better than if it was just at room temperature. If you are looking to store it for longer than that, it might be worth trying a vac sealer; however, I wouldn't be surprised at all if the coffee held up fine without one.
This is an area I want to test out more: we currently have an experiment on the go to compare coffee stored in a tied up plastic bag with samples that have been vacuum-sealed after several months in the freezer. I'm hoping to do a small scale blind tasting with these soon, and maybe set up some larger tasting experiments later.
To flip the question, when do you think it is not advised for a consumer to freeze coffee?
If you are going to use it within a month or two of the roast date, there isn't a huge benefit to freezing beans that are being used for filter coffee. If the packaging is airtight, it isn't really necessary. On a related note, I would also recommend setting a limit on how much room in your freezer you devote to coffee too, as it can spiral out of control easily if you have hoarding tendencies... so I have heard.
You noted in a Manchester Coffee Archive document that coffee ages slower in the freezer. Can you describe how freezing coffee affects the longevity of the product?
Ah yes, "What We Know about Freezing Coffee Beans" is a work-in-progress collation of all the info I have been able to find about coffee freezing over the years. There's a fair bit of detail in there about how freezing can be beneficial for coffee storage, but my favourite nugget is that one day of storage in the freezer is basically equivalent to 90 days at room temperature . So coffee, in theory, should last in the region of 90 times longer from when it is first put in the freezer. This is based on some clever science from Michael Cameron and Christopher Hendon, two big names in the coffee freezing world.
For consumers at home who have not already frozen coffee, what steps should they take to freeze coffee? In what container should coffee to go in the freezer be stored?
There are a few options: zip-lock bags (I like the "Swedish" ones), jars, bottles, or even just the original bag. If you use the original bag, I'd suggest taping up the valve as they can sometimes leak air into the bag. If you are opening and closing the container, watch out for drops of condensation getting in when you put it back in the freezer. As far as I can tell, condensation doesn't seem to form on the beans themselves but it will form quickly on glass and plastic, on the surface in contact with air.
The only method we have used consistently over long stretches of time is vacuum-sealed bags, so that is usually what I would go for if it is a fancy coffee that you want to hold onto for a year or so. If you only want to use a little bit, you can seal the bag up again easily and it keeps everything neat in the freezer too.
What coffee(s) are you drinking at home at the minute?
I've been cracking open the Fancy Beans from the bottom of the freezer recently: this week I have been brewing a Pacamara from Finca Margarita (Talormade) and a Maragogype from Santa Rosa (Onyx), both from December 2019.
How many samples do you have in the archive? Is there a limit?
We have 529 coffee samples in the Archive currently. At the moment it is split between two freezers in my basement. However, my own personal coffee is in there too so that uses up some of the space.
The limit is set to how many I can stuff in the freezers and still maintain organisation. I think we could get 600+ in the two freezers we have if mine wasn't taking up so much room. When we are running events this isn't such an issue but at the moment nothing much is being used so it is quite full.
What is your favourite snack to enjoy with a cup of coffee?
A cinnamon bun is my current go-to.
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Check out the other posts I have written related to this article.
- Coffee Chat with Brewing Coffee Manually
- Coffee Chat with Edinburgh Coffee Shops
- An Unknown Coffee Tasting
- Why I Drink Speciality Coffee
- How I Learn About Speciality Coffee
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