What We Know About Freezing Coffee Beans

Tom Finch - Co-founder/Archivist, Manchester Coffee Archive

Updated: 28/07/2022

MCA Freezer - several vacuum sealed bags of coffee

Aim

This is an attempt to collate all the currently available information on the topic of freezing roasted coffee in order to preserve it for long periods of time. Freezing allows MCA to exist, so it has therefore been important for us to investigate best practices.

I will focus on my own experience as a coffee enthusiast and MCA archivist; however, I welcome input from anyone willing to share their experiences, either at home or in a professional setting.

I am by no means an expert in freezing coffee: I have researched and learnt from the work of some far better qualified individuals, referenced in this guide. I think there is still much that could be explored in the world of coffee freezing, so if you would like to get in touch to share your own findings, or if you spot any inaccuracies, please drop me an email.

If you find this guide useful, then feel free to show your appreciation by buying me a coffee. I do drink coffee too, occasionally.

Aim
Contents
Introduction
The benefits of freezing coffee
Coffee storage methods
Vacuum sealing and freezing
- What we use at Manchester Coffee Archive
Freezing in reusable containers
Other freezer storage methods
Vacuum sealing workflow examples
- Vacuum sealing and resealing with vacuum bags
Guidance notes
Reuse and recycling
Appendix - Areas for further research
- Experiments MCA would like to do
- Areas for further research
Bibliography
Changelog

Introduction

I started freezing coffee in 2018; my initial aim was to preserve a sample of each coffee I drank so I could taste them all together at a later date. I later realised that freezing also allowed me to preserve larger portions of coffee so that if I saw a coffee I wanted to try, it wouldn’t matter that I already had enough coffee on-the-go, I could just freeze it until I actually needed more coffee. This flexibility totally changed the way I buy coffee for myself, and means I never waste any at home.

The collection of coffee samples I amassed over time eventually led, through encouragement from the rest of the Archivists, to the founding of Manchester Coffee Archive. Anyone could do the same if they wanted to… but be prepared for a lot of admin and data entry.

It should be noted that coffee does not technically “freeze” (as stated by Hendon) since it is solid at room temperature; “freezing” coffee refers to “cooling of coffee to at least freezer temperatures” and is used as shorthand.

The benefits of freezing coffee

The benefits of freezing coffee apply to both the home enthusiast and coffee professionals. Freezing coffee:

“Stops the clock” on the ageing process
Preserves coffee at peak flavour
Can ensure you never run out of coffee
Helps you keep a variety of coffees in stock
Reduces fear of missing out on a coffee you want to try
Improves grind consistency
Enables you to save coffee to contribute to MCA

Stopping the clock

Freezing allows you to massively reduce the rate at which coffee stales over time, and allows you to preserve the flavour over a very long time period.

“… for every 10ºC you cool something down, most of the processes occurring in the bean occur at half the rate. So cooling of coffee should prevent chemical reactions that occur over time (like staling or aging), by making them proceed extremely slowly.”

- Christopher Hendon - interview with The Little Black Coffee Cup

The Arrhenius equation can be used to derive the following, as calculated by Michael Cameron:

Temperature	Equivalent number of days aging at room temperature (25ºc)
-18ºc approximately (domestic freezer)	90 days
-30<40ºc approximately (commercial freezer)	237 days

This shows how much the shelf life of coffee can be extended by freezing, and this can be applied at any point. For example, when only taking temperature into account:

Coffee frozen on Day 7 past roast will take 2070 days (5 years 8 months approximately) (23 x 90) to reach the same point in the aging process as the same coffee left at an ambient temperature of 25ºc for 30 days
Coffee frozen on Day 25 past roast will take 450 days (5 x 90) to reach the same point in the aging process as the same coffee left at an ambient temperature of 25ºc for 30 days

This is an oversimplification, but it gives an indication for how long coffee can be preserved with even a normal domestic freezer. Freezing has potentially massive benefits for those wishing to preserve coffee at its peak flavour.

It should be noted, these estimates are only taking storage temperature into account and other variables may have a negative effect on flavour during the storage time. One important consideration is the storage method in the freezer: at some point, coffee stored in a non-airtight bag will most likely not taste as good as coffee stored in a vacuum sealed bag, although the point at which the storage method becomes an issue is something we’re still trying to figure out.

Preserving coffee at its peak flavour

Freezing avoids the issue of coffee going stale. If you know you won’t use a full bag within the peak window of flavour, freezing allows you to continue to enjoy the coffee at its optimum taste. For consistency, at MCA we aim to freeze coffee at ~10 days past roast, effectively capturing the flavour of the coffee at that point in time.

Finding the optimum time to freeze coffee will depend on the optimum rest period for the specific coffee, and this can vary considerably. Lighter roasts in particular may taste best 2, 3 or more weeks after roast and it is worth considering this when deciding at what point to freeze a particular coffee. Roasters with a lighter roasting style such as Lüna, La Cabra and Talormade have noted that their coffees can taste good up to 3 months past roast, and the peak flavour may be several weeks past roast. Alexander Mills has written about this in more detail in his blog.

Never running out of coffee

This process can be as simple as freezing half of each bag of coffee you buy at home, or buying two bags instead of one when visiting a coffee shop. Freezing means you can keep as much coffee in stock as you like and you are limited only by the amount of room in your freezer that you want to devote to coffee storage.

Keeping a variety of coffees in stock

Freezing allows you to maintain a wide selection of coffees with minimal effort. If you freeze some of each coffee you buy this allows you to enjoy a range of coffees throughout the year, and revisit coffees you have particularly enjoyed. Since coffee is a seasonal crop, coffees or certain origins are easier to get hold of at different times of year; freezing allows you to avoid this limitation.

No more fear of missing out

Freezing makes fear of missing out on limited-run coffees a thing of the past. If a super-fancy coffee becomes available and you already have a few bags on the go then you can buy a bag without having to worry about when you will use it.

Improving grind consistency and distribution

The work of Christopher Hendon at his team, published in Nature goes into great detail about the effect of temperature upon grind particle distribution and grind consistency. An explanation of the findings was posted on Barista Hustle, which makes some recommendations based on the paper.

Contribute coffee to MCA

Freezing allows you to keep hold of the coffee sample until you are able to share it with us at one of our tastings, for inclusion in the Archive.

Coffee storage methods

There are lots of ways to store coffee, in or out of the freezer. It can be difficult to know which method is best, and this will vary depending upon how long the coffee is being stored. Vacuum sealing with plastic bags currently seems to be the best available option for long term freezer storage, which is why we use it to archive coffees for MCA. However, if you want to give freezing a try, there are alternatives as simple as just putting the unopened bag in the freezer - I have explored some of these options below.

There is a surprising amount of debate about the best way to store coffee, but the three main factors that affect how quickly coffee will deteriorate are:

Amount of air in the container
Amount of air getting into the container
Temperature

Reducing temperature reduces how fast the coffee will age, so the freezer takes care of this one. The other two factors are dependent on the storage container. Freezer air can be damp and potentially odorous so it is important to try and keep this out.

Vacuum sealing and freezing

Air contains roughly 20% oxygen and this can either be removed by sucking the air out displacing it with an inert gas (such as carbon dioxide or argon). Oxygen causes oxidation, and therefore degradation of coffee, and so ideally needs to be removed as much as possible from the coffee storage. Vacuum sealers are a simple way of removing air from a bag of coffee prior to sealing.

Vacuum sealers vary in their performance, and some will pull a more complete vacuum than others. This is indicated by the kPa rating, which is usually between 70-85kPa for domestic vacuum sealers. When vacuum sealing coffee, the plastic wraps tightly around the beans, reducing the amount of air inside the package; however, air will still remain in the gaps that remain in the package. The amount of oxygen remaining in these gaps depends on the kPa rating of the vacuum sealer, but may be ~80% of atmospheric levels: this can be calculated using the formula and conversion table on The Engineering Toolbox (link). Heavy-duty chamber vacuum sealers can pull out closer to a 99% vacuum but these are much more expensive than domestic sealers.

Cutting out the original packaging label and put it inside the bag with the coffee is an easy way to identify the coffee, alternatively a permenant marker can be used, just make sure it is waterproof.

Most domestic vacuum sealers require embossed/textured plastic and will not work with smooth bags. Make sure the plastic roll/bags you buy are suitable before you buy in bulk.

Vacuum sealing bags come in a variety of sizes, so you will need to pick an appropriate size for your needs - sometimes vacuum sealers come with a few sample bags which can be useful for this purpose. Vacuum sealing plastic is also available on a roll, which can be used for making your own perfectly sized bags; however, you will need to create a bag each time by sealing across the roll. I have found 20cm x15cm wide bags, made from a 15cm wide roll, work well for 100g portions as it allows the bag to be flattened fully.

If you are making your own smaller bags, note that sometimes the vacuuming process will fail if there is not an original edge on the left and right side when vacuum sealing the bag (see examples below). The wide, flat surface of the original edges enable the vacuum sealer to create a seal when vacuuming the bag, and without this it sometimes will not work. When I have been able to pull a vacuum on a bag with heat seals on the left and right side, I have found that some of these bags leaked over time, indicated by the plastic becoming loose. This may be a rare occurrence, but it is something to watch out for if you are making your bags in this way. To minimise potential leaking, I use 12cm and 15cm width rolls for all my freezing, as it provides good flexibility, at the expense of a little bit of time spent making bags.

Heat-sealed vs original edges Left: heat-sealed edges on left and right side - Right: original edges on left and right side

What we use at Manchester Coffee Archive

Aicok Vacuum Sealer - from Amazon (£40 - may now be unavailable, but there are many similar models)
12cm and 15cm wide rolls of vacuum sealing plastic - embossed/textured plastic suitable for domestic vacuum sealers (various prices on eBay/Amazon)
Permanent marker - to label the bags
Chest freezer (only used for coffee)

Coffees are frozen at around 10 days past roast, where possible. Samples are labelled with the freeze date and basic information about the coffee (the rest is on a spreadsheet). Since the coffees are transported offsite, we decant the required amount into a small container and re-seal and freeze the remaining coffee.

Freezing in reusable containers

Vacuum sealing is a very popular option for freezing coffee, but there are alternatives. With each of these options the main factors to consider are:

How good is the seal (i.e. how much air is likely to leak into the container)?
How much excess air (headspace) is in the container?
For how long will the coffee be stored?

By using reusable containers instead of vacuum sealing it is possible to avoid generating plastic waste while enjoying the benefits of freezing. Todd Souter has suggested that reusable containers (in this case centrifuge tubes) are only suitable for espresso doses, and not filter coffee, but I have not seen the data that supports this and would argue that the suitability could depend on a number of factors, such the duration of freezer storage.

This is an area that I would like to investigate further before making any firm conclusions on the longevity of coffee stored in this way. In 2020-2021 I have been routinely using 60ml reusable containers to freeze 25g doses for filter coffee and have really enjoyed the flexibility this provides. Furthermore I’ve not noticed any drop in the quality of the brews. In the absence of any further research, for now I would cautiously recommend trying reusable containers if you would like to avoid plastic waste (and potentially speed up your freezing workflow).

Reusable containers - no vacuum

60ml and 40ml reusable containers

Small reusable plastic containers can be used in place of vacuum sealing plastic. Centrifuge tubes have seen widespread use across the world as they generally hold up to 20g of coffee, making them ideally suited for espresso doses. Single dose containers designed specifically for coffee (including freezer storage) are also produced by manufacturers such as Weber Workshops, who sell Bean Cellars with 22-30g capacity (plastic version) and 18-22g capacity (glass version).

Specimen containers are widely available in a range of sizes through laboratory supplies, eBay and Alibaba: the most useful sizes for single doses of coffee will be 40ml, 60ml and 90ml. Laboratory supplies will often have a high minimum order quantity (usually 100 units), but the unit cost is very low. eBay may be the easiest way to obtain a few for home use: search for “specimen” or “histology” containers and the appropriate size to find the available options. So far, my favourite containers are Leakbuster containers from Starplex (very high quality lids) and these green-lid histology containers (available on eBay/Alibaba) - see above.

Coffee beans vary widely in density and shape, meaning the capacity of a reusable container will vary depending upon the bean. The roast level also affects capacity: a darker roast will occupy more space than a lighter roast of the same coffee. From testing out various beans and storage containers I have found that 1ml of storage can generally hold 0.41-0.45g of light/medium roasted coffee, but this can vary between different container shapes: a long, thin container may hold less than a wider container, particularly for larger beans.

Sub-Zero Coffee’s packs of centrifuge tubes have a suggested capacity of 20-22g, and I have tested various light-medium roast coffees with 40, 60 and 90ml containers. Based on this information I have compiled the table below which may use useful in selecting an appropriate container size. I would recommend selecting based on the lowest listed capacity to avoid buying containers that may end up being too small at some point (e.g. when attempting to fit 20g of a Pacamara variety into a 40ml container).

Container	Approximate Capacity (Light-Medium Roast)
40ml specimen container	16-20g
50ml centrifuge tube	20-22g
60ml specimen container	25-29g
90ml specimen container	33-41g

I would like to test reusable containers further, to see how they compare to vacuum sealing in the long term. I have heard of several people using reusable containers for both filter and espresso beans, and have tried it myself with positive results, but am yet to gather sufficient data to make any reliable conclusions.

One thing to note when choosing a reusable container: be aware that some type of plastic (e.g. PP - polypropylene) may become brittle when stored at freezer temperature, which could lead to them cracking.

Reusable containers - with vacuum

Reusable containers with valves for attaching a vacuum sealer may appear promising but they are not without issues. The effectiveness of these contained will be dependent on how well the seal and valve maintains the vacuum within the container over time. When I have tried zip-lock bags with valves I have found that air sometimes leaks back into the bag within a few days, particularly if the bag has been reused.

The method used by Aaron Clark at Botany Coffee is a promising solution for cafes and avoids the use of disposable plastic. A vacuum degassing chamber and small glass jars are used to freeze individual doses of coffee. Aaron Clark has stated that the vacuum appears to be maintained for around 3 months using this method, which could therefore be viewed as an appropriate timeframe to use this storage method:

“Coffees in a freezer for longer than 3 months tend to lose their seal. The biggest indicator is that there is less resistance to the lid opening when the seal is compromised. Our freezers only go to -25C generally and are opened frequently hourly. I imagine that could affect the longevity of the seal”

- Aaron Clark - 12/5/2019

Flushing with inert gas

Displacing air in the container with inert gas (flushing) is a technique used widely in retail coffee packaging and can be very effective at removing oxygen without the need to create a vacuum inside the bag. I haven’t, unfortunately, found an easy way to use this technique at home yet.

If anyone has developed an inexpensive method to flush small reusable containers with inert gas I would love to hear about it!

Pressurising with inert gas

Matt Perger has suggested reusable valved containers, pressurised with inert gas as a potential alternative to vacuum sealed plastic in discussions on his Telegram Channel. This sounds very promising, but the necessary equipment may be difficult for many to obtain. I would be interested to hear about anyone successfully implementing this technique.

Other freezer storage methods

There are other storage method that can be considered when freezing coffee:

The original bag - press out as much air/gas as possible and tape up the valve (electrical tape or duct tape works well) or put it in a ziplock bag. If the bag was previously flushed with inert gas, the coffee will preserve particularly well as there will be even less oxygen in the bag. If there’s no valve you can try just putting it straight in the freezer or puncturing the bag to press the air/gas out (and then taping over the puncture). This may well be the best option for freezing a whole bag of coffee, particularly if the bag has been flushed with inert gas.
Ziplock bags - bags with a double seal are a good option, I like the ones from IKEA. Press out the air, or use a straw to suck out the air if you like, and seal the bag.
Glass bottles - silicone stoppers can create a good seal.
Glass jars - make sure it has a tight-fitting lid.
Tied-up plastic freezer bag - low cost and takes up very little space. Press out the air and tie it up tightly.

These are some are low cost options that are available if you want to try freezing some coffee. It would be interesting to know exactly how well these methods perform over time, and I’d like to test these out more to be able to provide better recommendations; however, if you want to preserve coffee for a few months, possibly more, these are all options worth considering.

There are a few storage methods I don’t recommend: reusable ziplock bags with valves are appealing but I have found that air tends to leak back into these quickly, particularly after being reused. Ryan Woodgate has mentioned having similar experiences with them. Rigid plastic containers or bottles with vacuum valves have similar issues: the partial vacuum inside the container is essentially trying to suck air in all the time so any imperfections in the seal will cause air to be leaked back into the container. Also, Fellow do not recommend using their Atmos Vacuum Canisters in a freezer due to negative effects on the seal.

Vacuum sealing workflow examples

There are two main options when using vacuum-sealed plastic bags:

Vacuum-sealing and resealing bags
Single-dose bags

Vacuum sealing and resealing with vacuum bags

This is a good method to use if you just want to make one or two cups of coffee at a time and this is therefore what I do with most coffees at home. This method is great for particularly fancy coffees that you want to hang on to for a while.

Method

Coffee is portioned into a prepared bag and frozen. If only removing 12-15g portion at a time a 12cm wide bag may be appropriate, as this will give you enough empty space after removing each dose; larger doses will be better suited to a wider bag, and will require some trial and error.
When you are ready to brew, remove the package from the freezer, cut a small incision so you can portion out the dose (e.g 12<15g) and immediately reseal the bag and return to the freezer. I reseal and freeze at this point to avoid storing the beans at room temperature as much as possible, and it is good to get it out of the way.
Grind the frozen coffee and brew.

Notes

With my vacuum sealer, I need to seal approximately 1-2 cm of the bag each time I open it, due to the gap between the vacuum chamber and the heat sealer. When using a 12cm length of 15cm wide roll a 14g dose of coffee can be removed, and the bag re-sealed. However with a wider roll/bag removing such a small amount may not allow for the vacuum sealer to close, so more coffee will need to be removed.

As I work my way through the bag I end up with 1-2 cm strips of plastic as each re-seal point.

Using this method means the bag itself cannot be reused as it is cut up, but removing entire bags from the freezer could allow the bags to be reused.

Resealing an opened bag: the cut edge is just inside the vacuum chamber

Resealing an opened bag: the cut edge is just inside the vacuum chamber. The bag reduces in length by 1.5cm approx between resealing (indicated by arrows on the right)

Resealed bag - showing two seal points

This 100g bag has been re-sealed twice - the seal points show the minimum cut-down amount for each re-seal with my old Crenova vacuum sealer (1<2cm) - the maximum size of the storage section is preserved and could potentially be reused as a small sample bag once empty (depending on how much is left)

Single dose bags

This is what we do for all the coffees contributed to MCA for tasting events throughout the year. The same process could be used for preparing single-dose bags for espresso or filter coffee.

I tend to buy unbranded 12cm and 15cm wide rolls of vacuum sealing plastic from eBay sellers, normally buying 5 rolls at a time. Local and online availability may vary depending on where you are located, but search “12/15cm vacuum roll” and you should see a few options.

Alternatively, individual bags can be purchased, such as the 10x15cm Fresherpack bags found on Amazon; however, these can potentially work out more expensively. For small portions of coffee I have found that preparing bags from a roll myself was roughly a third of the cost compared to purchasing individual bags (when buying 100).

As a reference, at MCA we seal 13-26g samples of coffee in 10.5cm x 12cm prepared bags (cut from a 12cm roll of vacuum sealing plastic).

Sealing a bag - showing 1-2cm gap required

Sealing a sample bag with a Crenova vacuum sealer - the coffee would need to be about 1<2cm below the heat sealer to close the lid and seal the bag

Guidance notes

Refreezing coffee

This has long been thought to have a negative impact on coffee, but current advice is that refreezing of roasted coffee does not appear to have any significant negative effects. This may be due to the extremely low water-content of roasted coffee. Michael Cameron has advised that re-freezing is not something to worry about:

“this ain’t chicken, you can re-freeze”

- Michael Cameron - Freeze Beans not Peas

One issue to point out though: the vacuuming process will remove air and inert gases surrounding the beans and held within them. Matt Perger has suggested that vacuum sealed coffee stales quickly if re-vacuumed, essentially acting as a “sponge” for oxygen being sucked back into the container. Whether or not this is counteracted by the freezing process is something that could be investigated further.

The best time to freeze coffee

Since freezing essentially “stops the clock”, freezing at the time the coffee tastes best is, in my opinion, the best time to freeze. However, when the flavour is starting to fade, freezing still might be a good option to preserve the coffee as long as possible. At MCA we tend to freeze from 10-30 days post roast, depending on the roast level: lighter roasted coffee may benefit from a longer rest period.

“There’s a bunch of literature on degassing effects, and how to test it, but so much is dependent on a) the bean and b) how it was roasted. 7-10 days is the window for *most* coffees being fully degassed. I wait 9 days, in a temp controlled environment, bag open, then vac seal and freeze”

- Michael Cameron

Grinding from frozen

If you want to use coffee stored in the freezer, there is no need to let it defrost: you can use it straight away. Frozen coffee beans have been found to produce a narrower spread of particle and a finer grind size, so you may need to adjust your grinder to a coarser setting depending on how you are making coffee.

Todd Souter mentions this in his guide to using frozen coffee beans: he suggests a setting 2-notches coarser on an EK43 for espresso. This adjustment will vary depending on grinder though, so it is worth testing it out and making a note of the adjustment needed.

Other brew methods, such as V60 or Aeropress, are more forgiving to grind size variation so there may not be any noticeable difference when using the same setting used for room temperature. Zaparz Mnie suggested to me that using a 20 micron coarser grind setting is required (using a Mazzer ZM) when grinding from frozen for filter brewing. Personally, I have not tested this enough to make any firm conclusions: I tend to just use the same grind setting for room temperature or frozen beans (with a Lagom P64 grinder).

Removing coffee from the freezer and using at room temperature

Allowing the coffee to come to room temperature (e.g. if using the coffee over the course of a day/week) means the potential benefits of grinding from frozen are lost, but this may be more practical if you know you will be using the coffee over a relatively short period of time. Mat North (of Full Court Press and Raw Material) and others have noticed that coffee seems to age faster when removed from the freezer, so I’d recommend only taking out what you will use in the next day or so. I’m not sure what would cause this accelerated aging: it could be due to the vacuuming process (if used) or the temperature change itself, but I’d be interested to hear of any experiments that have been done to investigate this.

Originally I was under the impression that a package of coffee removed from the freezer should be allowed to reach room temperature before opening the package and storing at room temperature for any length of time due to concerns over condensation forming on the beans and accelerating oxidation; however, as mentioned above, from speaking to Michael Cameron about this concern and doing my own tests it doesn’t seem to be an issue: condensation forms on the packing packaging but does not appear to form on the beans themselves.

Storing vacuum sealed coffee at room temperature

There are differing opinions on whether vacuum sealed roasted coffee should be stored at room temperature. Jonathan Gagné has written about his positive experiences of vacuum sealing and storing coffee at room temperature for several months. This is not something I have tested myself.

Angus Mackie (Ona Coffee), has suggested that the vacuum-sealed environment can potentially have a negative effect on the coffee:

“Have been tasting same coffee packaged in vac sealed bags (not frozen) vs valved bags. Also with storage containers such as Illy tin vs valved bag. And coffee that is still quite young in air scape containers vs bags. And found quite similar patterns with how coffees tasted. When in a completely sealed environment at room temp, coffee had less sweetness, noticeably higher dryness, and quite a consistent savoury flavour that was not in those coffees in the ‘regular’ packaged environment”

- Angus Mackie

“In my testing, vacuuming or packaging into air tight/no valve environments, the range of times after roast I’ve done have been between 22 hours after roast and intermittently between 5-30 days after roast. Anytime when this happened, and anytime coffee was taken from a valved environment into a completely sealed environment between 5-30 days, or straight into vacuuming and not freezing, similar taste degradation occurred”

- Angus Mackie (in reference to the article by agoodcleansavage re: sealed packaging)

Todd Souter (Barista Trainer) recommends freezing coffee within 10 minutes of vacuum sealing, stating that the natural carbon dioxide inside the bag can result in a “’choked’ or bitter, savoury flavour”. This raises an interesting issue: whether or not coffee stored in an airtight/sealed environment degrades in quality at a more rapid rate than coffee stored in a traditional one-way valve bag. Research originally circulated by Colonna in reference to their decision to remove valves from their packaging suggests that the addition of a valve does not have a positive impact upon preserving flavour. If roasted coffee is stored vacuum-sealed at room temperature for an extended period (e.g. a couple of days) gas may be released from the coffee (degassing/oxidisation) causing the packaging to loosen. Even if the potential effect on flavour isn’t a concern, this can make the bag more vulnerable to tearing.

This is an area where opinions vary, and I have not investigated this myself: for now, I tend to only vacuum seal when I am going to put the coffee in the freezer, but wouldn’t be too concerned about temporarily storing the coffee at room temperature once sealed. As ever, I would be very interested to hear of any experiments that may have conducted to investigate this issue.

Reuse and recycling

Plastic vacuum sealing bags

These can be reused: either wipe the bags out with a bit of kitchen roll, or clean them out with water and detergent, but make sure they are fully dried before using again.

The bag will need to be cut down when reusing, so larger bags have more potential for reuse but will inevitably get smaller as they are re-used. Waste could be minimised by collecting a few smaller, re-used bags in one larger ziplock bag to keep them all together.

Vacuum sealing bags appear to be mostly comprised of PA and PA/PE plastic: the recycling options for this vary on location.

PA - polyamide (nylon)
PE - polyethylene

Recycling options for vacuum sealing plastic

Recycling options for vacuum sealing plastic will vary depending in your location, and you should check the guidance at your local facilities before putting it any recycling bin. 1914 Coffee Company have advised that vacuum sealer plastic can be recycled in “soft plastic” collections in Canada, so check and see if this is an option in your country.

Here in Manchester, the local recycling collection does not recycle PA or PA/PE plastic so vacuum sealing plastic cannot be recycled in your usual recycling bins. However, Co-op Food now have soft plastic collections at many of their stores: if you are based in the UK, check to see if your local Co-op has this facility. Other supermarkets may also have similar collections.

“The collection points in some supermarkets for plastic bags are only for polythene packaging like salad bags and bread bags etc. I’m not aware of any recycling facility for household PA. In Greater Manchester, the only type of plastic that can be recycled in the recycling bins at home is plastic bottles (all types including HDPE, PET and PVC).

In terms of PA, it’s not really down to guidance, it’s about whether there are any facilities that are capable of recycling the PA and whether there’s enough PA to make it economically feasible to develop the technology to recycle it. Any plastic that can’t be recycled will generally be sent to an Energy from waste facility and used to generate electricity.

You might find more information on the British Plastic federation website: http://www.bpf.co.uk/”

- Manchester City Council (2018)

It is frustrating that vacuum sealing plastic is not more widely recycled, but it is better to be aware of this issue that fall victim to “wishcycling”, a term I first heard on Last Week Tonight with John Oliver.

Biodegradable vacuum sealing bags

Biodegradable vacuum sealing bags are available, although I have not tried these myself. One example is Eco Pouch, produced by The Vacuum Pouch Company, based in Bury, UK. Thanks to Ryan Woodgate for the suggestion.

The guidance is that these bags are not suitable for storing liquid, and can be used for up to one year. Unfortunately the manufacturers have stated that Eco Pouch is not suitable for most domestic vacuum sealers, and requires a “snorkel” part which is inserted into the bag when vacuum sealing.

Vacuum sealers with a “snorkel” can be difficult to find, and I have never used one, but the SINBO DZ-280 is an example. In addition to biodegradable bags, this attachment also allows you to use non-embossed plastic, which opens up the opportunity to use a wider variety of packaging material.

When disposing of “biodegradable” packaging, it is important to check your local recycling guidance thoroughly as many items purported to be biodegradable may in fact not be suitable for local composting facilities. For example, Recycle for Greater Manchester (2018) advise that only packaging marked with the EN13432 seedling logo is suitable for local composting facilities, and is the only type of biodegradable packaging that should be put in green waste bins.

Appendix - Areas for further research

Experiments MCA would like to do

Freezer storage: vacuum-sealed plastic vs. sealed plastic
Room temperature: vacuum-sealed plastic vs. sealed plastic
Vacuum sealed frozen coffee portion, removed from the freezer to be transported at room temperature: keeping in original vac-sealed packaging vs. re-sealing without vacuum
Portion of vacuum sealed frozen coffee removed from larger package to be transported at room temperature: vacuum-sealed plastic vs. sealed plastic
Portion of vacuum sealed frozen coffee removed from larger package to be transported at room temperature: flushing with inert gas vs. sealed plastic
Comparing reusable frozen storage containers with vacuum sealed bags over time - at what point is the difference noticeable?
Comparing room temperature storage methods - at what point is the difference noticeable?
Investigate the use of oxygen scavenger sachets, silica sachets, carbon dioxide flush and nitrogen flush methods
How well do biodegradable plastic vacuum bags perform in a freezer? How long do they last before the seals fail?
Using inert gas and removal of only headspace in sealed packages.

Areas for further research

If a coffee is frozen on day 0 or day 7 for example, will it continue to age at the same rate after being defrosted? e.g. Would a coffee frozen on day 7 and defrosted then left at room temperature for 2 weeks taste as good as a coffee aged normally for 3 weeks?
Similarly, in order to facilitate a long-distance trade (7-10 day postal delivery) from several local sources, could a number of coffees be frozen on Day 0, saved up until a collection had been built, and then all removed from the freezer at the same day and be sent thawed? Would this effectively deliver all samples at approximately 7-10 day past roast performance? If coffees prepared in this way were received at MCA we would freeze the coffee again upon receipt so this raised the issue of re-freezing effects again…
Are freeze temps below -16 necessary for preserving coffee? Or are v low temps only beneficial for grind consistency?
Is cleaning out vac seal bags practical and effective? Does it need to not have any previous coffee odour at all? Also applies to normal coffee packaging, how clean does it need to be? Drying both of these seems tricky… (applies to reuse of coffee packaging in general but particularly relevant here since single use plastic is quite prevalent in coffee freezing)

Bibliography

Agoodkeensavage (2012) - Why I stopped packaging our coffee in one-way valves

Barista Hustle (2017) The Grinder Paper Explained

Bean Scene (2018) The big freeze: why there’s no longer a barrier to coffee freshness

Botany Coffee (2018) - Down the Vacuum Sealing Rabbit Hole

Cameron, M. (2017) Freeze Beans not Peas

Cameron, M., Chapman, M., Woodgate R., Mackie, A.G. (2019) IG Chat Discussion 13-21/2/2019- @wayfarerbarista, @onacoffee, @angus_gus_mackie, @1914coffeecompany, @strivefortone

Clark, A. (Botany Coffee) (2019) - Instagram Chat - May 2019

Colonna-Dashwood, Maxwell (2021) Benefits of Freezing Coffee. Research and tips

Gagné, J. (2019) Some Strategies to Keep Your Coffee Fresh

HBO (2021) Plastics: Last Week Tonight with John Oliver

Hive Coffee Project (2020) Hive Coffee Project: YouTube Channel

Hoffman, J. (2019) Weird Coffee Science: Microwave Your Coffee Beans

Hoffmann, J. (2020) The Best Coffee Storage Canister

Mills, A. (2019) Light vs Dark Roast Coffee - A case for longer shelf life

MOCON Europe (2020) Vacuum Packaging

Motoyoshi, U. (2019) The @wastingcoffee Guide to Not Wasting Coffee

North, M. (2020) Instagram Story re: freezing 23-3-2020

Ona Coffee (2018) New Sydney cafe to feature frozen coffee beans on menu