Freezing Coffee

With many of our favourite coffee shops forced to keep their doors closed over the last few months, the amount of coffee being consumed in our homes has skyrocketed. Whether you’re a full V60 convert with a temperature controlled kettle or just brewing up in a cafetière, the most common question we often get asked is same: what is the best way to keep our coffee fresh and tasting it’s best?

The concept of freezing coffee beans has been floating around the industry for several years but it wasn’t until recently that the benefits of freezing at home have started to be explored in a little more depth. To find out more we chatted with Tom Finch, co-founder of Manchester Coffee Archive, and a leading expert on home coffee freezing.

What is Manchester Coffee Archive and what do you guys do?

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 who wants to come and taste some nice coffees and meet fellow enthusiasts. We rely on coffee contributions to keep the Archive going, which currently holds over 400 different coffees.

So, what are the benefits of freezing coffee?

Freezing allows you to massively extend shelf life, which is how we are able to put something as ridiculous as MCA together. We have coffees in the freezer that are over two years old, they’re still tasting fresh and we expect that they will remain stable for some time before any noticeable degradation in taste occurs. It also means we can keep a variety of coffees in stock and not have to worry about running out. There are some interesting benefits to grinding frozen coffee for espresso, mainly to do with grind consistency and particle size distribution – we haven’t investigated this ourselves but coffee-freezing evangelists Michael Cameron (of St Ali in Australia) and Christopher Hendon (notable coffee scientist) have done interesting research on this subject, which I’ve highlighted in What We Know About Freezing Coffee (linked on our Instagram bio and website).

Will I need lots of expensive equipment? Do I need a vacuum sealer?

Vacuum sealing in plastic is the current “gold standard” in the coffee freezing world, but it is possible to get into freezing without purchasing a vac sealer. When packaging coffee to put in the freezer the aim is to both remove as much oxygen as possible from the packaging and also to keep the damp freezer air out of the packaging. Vac sealers do a great job on both of these, but I have heard anecdotally of people just throwing a retail bag in the freezer and it tasting great many months later. Lots of people use repurposed jars or even a humble ziplock bag. We have begun to investigate this more, we’ve done some experiments and have some experiments lined up to try and figure it out, but for now I would say just seal it up as best you can. However, if you want to really get into it and freeze coffee for a year or more a vacuum sealer is the way to go.

Can I just use my freezer at home?

Yes, most home freezers run at -20C which is fine to preserve coffee for at least a couple of years. We use two small domestic freezers at MCA, which will be fine until the walk-in bunker facility is complete.

Is there an optimum time after roast to freeze coffee?

Freezing essentially stops the clock, so whenever it tastes best is a good time to freeze. At MCA we aim for 10 days past roast, which is good for cupping, filter brewing or espresso, giving us a bit of wiggle room for when we come to use our little coffee samples.

What does freezing do to the beans? Do they taste different? Or taste better?

Here’s the thing, due to the extremely low water content of roasted coffee, it doesn’t really freeze at all. We call it freezing because… it is in the freezer. But, really, it is just super-chilled to slow down all the biological processes that are happening in the beans. In our experience coffee from the freezer tastes the same as it did before it went in. The only way frozen coffee tastes better is that you don’t ever end up brewing stale coffee!

Do you need to let the beans defrost or can you grind from frozen?

You can use beans straight from the freezer in the same way as if they were at room temperature, although you might need to adjust your grinder to a slightly finer grind setting. It is best to just try the same grind settings you would normally use first and take it from there. At home I often freeze a couple hundred grams at a time. When I take a bag out of the freezer, if I only want a cup or two of that particular coffee, I weigh out what I want then reseal and put the bag back in the freezer. If I decide that I want to drink that coffee for the next few days in a row, I just keep the bag out and let it come to room temperature over time. This “unpauses” the clock on ageing, but since I froze the coffee fresh, it doesn’t matter.

Can you keep refreezing the same bag of coffee or only do it once?

Re-freezing seems fine for coffee beans, we did a very small-scale experiment a while ago where we blind tasted coffee re-frozen multiple times vs. coffee that had been frozen once and there didn’t seem to be a noticeable difference. My favourite soundbite on this is from Michael Cameron: “this ain’t chicken, you can re-freeze!”.

Are there any biodegradable vacuum sealing plastic pouches on the market?

There are, but the ones we have come across so far aren’t suitable for most domestic vacuum sealers like the one we use at MCA. Freezer air is quite damp so you need to be careful using any material that will degrade in that kind of environment. Vacuum sealing plastic can be reused to some extent, but unfortunately recycling options for this type of plastic are very inaccessible in the UK. I would point out that by freezing in plastic like we do, we are avoiding wasting coffee, an issue on which Umeko Motoyoshi has curated a great deal of information in Not Wasting Coffee. Creating one type of waste to avoid another is a trade-off we’re happy with for now, and we hope that more alternatives will be available in the future.

Manchester Coffee Archive tastings are currently on hold due to COVID-19 but they are planning to return when it is safe to do so.

To find out more and contribute to the archive you can find them here.