Jump to content
RA5040

Vacuum packing & freezing freshly roasted beans

Recommended Posts

I know that there has been quite a lot of discussion about vacuum packing and freezing on this forum, but I thought I would start a new thread as I'm doing some experimentation vacuum packing and freezing immediately after roasting.

 

There's very interesting research on roasted bean outgassing here: https://atrium.lib.uoguelph.ca/xmlui/bitstream/handle/10214/8152/Wang_Xiuju_201405-PhD.pdf?sequence=2#page68. What was particularly interesting to me was the effect that humidity has on outgassing: many times greater than temperature. However temperature also has a major effect.

 

So I wondered what would happen if I vacuum packed and froze the beans immediately after roasting. My thinking was that the vacuum packing and freezing would reduce the oxygen significantly, cut down the humidity to zero and lower the temperature to -19 or so: all of which should have a big effect on outgassing. My hope is that outgassing is directly tied to staling ...

 

So what I have done so far is to roast one lot of Colombia Supremo to just 2nd crack (Medium Dark) and one lot of Yirgachefe to about 30 second after end of 1st crack (Light Medium). I divided both lots in two and vacuum packed both straight after roasting (I cooled the beans down quickly with a fan). I've put one set of beans in the freezer and kept the second set in a cupboard at room temperature.

 

After one day the Colombia at room temperature had outgassed a bit. The Yirgachefe at room temperature had not, and neither the frozen Colombia nor the Yirgachefe had outgassed at all.

 

I'm now into day 6 and the Colombia has outgassed a bit more (total of 250ml of gas for a bean weight of 100gms). The Yirgachefe at room temperature hasn't outgassed at all and neither have the frozen beans.

 

From the PhD thesis above, it's not unexpected that the dark roast would have degassed more. But it is a bit surprising that the light roast Yirgachefe has not outgassed at all. What is really good news, to my mind, is that the frozen beans haven't yet outgassed at all.

 

Still, it's early days, and the tasting test is yet to come. If there's any interest in this experiment I'll keep this post updated.

 

Cheers

 

Robert

Edited by RA5040

Espresso Machine: La Pavoni Europiccola ERG, Grinder: Baratza Forte BG, ​Roaster: Gene Cafe CBR101

Share this post


Link to post
Share on other sites

That paper is a Thesis and no doubt it helped him gain his PhD, but really I would put too much faith in that study at all. It's not particularly well done and appears to make a number of assumptions based on other research that also appears to be questionable....or at least questionable as to the assumptions he has drawn.

 

To keep it very simple, pretty much all CO2 is formed after roasting, it's not trapped in the coffee and is from Oxidation type reactions. It's why temperature affects this...these sorts of reactions have a reaction rate that doubles for every 10C rise in temperature. Packing as soon as possible after roasting is a good thing. Removing as much Oxygen as possible, without vacuuming to a solid brick (e.g. creating negative pressure) is very desirable.. Freezing slows the reactions further, but I am unsure as to the effect on other compounds that give coffee it's flavour (as well as help with mouthfeel and flavour transport).

 

I no longer pack coffee into bags with a 1 way valve...but I try and pack as soon as possible after roasting. In addition I have had coffee that I have unpacked (with a relatively small amount og gas formation), ground really really fine (read powder). I left it for about 30 minutes, then repacked it.....I then get a lot of gas formation, due to the exposure to Oxygen and increased surface area.

 

Vac pack, but not to a solid brick....then perhaps freeze, or not freeze...try each way based on taste, grind and pour performance.

 

I have been testing all this stuff out for 4 or 5 years now....one other tip...if you can smell the coffee wherever you store the packages....find packaging where you can't smell it!


 My reviews at https://coffeeequipmentreviews.wordpress.com/ - Various Machines and grinders, Amazon Dalian 1kg Drum Roaster: YouTube channel at https://tinyurl.com/szhgxzl .......

Share this post


Link to post
Share on other sites

Great! Just what I was hoping to hear! I suspected that the 'trapped CO2' was pretty much nonsense because it would have to have been hugely compressed to give out something like 10mg per gm of roasted coffee ... which leaves oxidation or some other chemical reaction ... and with little oxygen available and low temperatures this should drop down to very little. But humidity does seem to be a factor, so freezing makes sense, providing it doesn't affect the taste, mouthfeel and grind. As I have the same beans both frozen and not frozen I should be able to get a feel for the effect of freezing.

 

I also think that your suggestion of not using a low vacuum is very good: there's no point in sucking out all of the good stuff!

 

Cheers

 

Robert


Espresso Machine: La Pavoni Europiccola ERG, Grinder: Baratza Forte BG, ​Roaster: Gene Cafe CBR101

Share this post


Link to post
Share on other sites
Great! Just what I was hoping to hear! I suspected that the 'trapped CO2' was pretty much nonsense because it would have to have been hugely compressed to give out something like 10mg per gm of roasted coffee ... which leaves oxidation or some other chemical reaction ... and with little oxygen available and low temperatures this should drop down to very little. But humidity does seem to be a factor, so freezing makes sense, providing it doesn't affect the taste, mouthfeel and grind. As I have the same beans both frozen and not frozen I should be able to get a feel for the effect of freezing.

 

I also think that your suggestion of not using a low vacuum is very good: there's no point in sucking out all of the good stuff!

 

Cheers

 

Robert

 

Exactly right re the CO2 and again right about sucking out all the good stuff. A negative pressure is simply more likely to pull oils out to the surface and we don't really want that. Oxygen+Coffee is one of my big dislikes and hence why I am enjoying the airscape storage cannisters so much when I decant the coffee from it's storage bag....I must do a little Vid on the airscape stuff...so busy with other things (well mainly the Lelit Bianca) right now.


 My reviews at https://coffeeequipmentreviews.wordpress.com/ - Various Machines and grinders, Amazon Dalian 1kg Drum Roaster: YouTube channel at https://tinyurl.com/szhgxzl .......

Share this post


Link to post
Share on other sites
Exactly right re the CO2 and again right about sucking out all the good stuff. A negative pressure is simply more likely to pull oils out to the surface and we don't really want that. Oxygen+Coffee is one of my big dislikes and hence why I am enjoying the airscape storage cannisters so much when I decant the coffee from it's storage bag....I must do a little Vid on the airscape stuff...so busy with other things (well mainly the Lelit Bianca) right now.

 

Have you found any difference in taste etc., between the bricked vacuum packs and the soft ones with a little air left in, or is it mainly theoretical / common sense? I'm going to try to compare the two, but I doubt that my sense of taste and smell (or my experience with coffee) would be good enough. Still, I might be surprised!

 

I deliberated about the Airscape ... but couldn't quite get myself to pay the price, especially as I would have needed at least 2 for a choice of beans. But I got a couple of these: https://www.amazon.co.uk/gp/product/B075NKWKND/ref=oh_aui_detailpage_o02_s00?ie=UTF8&psc=1. The seal on them is good, but I don't know how effective the one-way valve is. What I'm intending to do but haven't quite gotten around to it yet is to use a CO2 bicycle pump (something like this: https://www.amazon.co.uk/CO2-Pumps-Inflator-Head-Accessories/dp/B077VH84PS/ref=sr_1_1_sspa?ie=UTF8&qid=1531056340&sr=8-1-spons&keywords=co2+bicycle+tire+inflator&psc=1) to displace the oxygen. I guess it should work.

 

Cheers

 

Robert


Espresso Machine: La Pavoni Europiccola ERG, Grinder: Baratza Forte BG, ​Roaster: Gene Cafe CBR101

Share this post


Link to post
Share on other sites

My initial results are as follows:

- vacuum packing definitely keeps the beans fresh (don't know for how long at this point)

- the vacuum-packed beans stored at room temperature degass a bit (varies depending on beans and roast level: Yirgachefe roasted light appears not to degass at all; Colombian Supremo roasted medium degasses a bit; Colombian Supremo roasted dark degasses quite a bit (about double the volume of the beans)

- the vacuum-packed beans stored in the freezer do not degass, or only very little

- I've only compared one set of Colombian Supremo stored at room temperature to the same beans stored in the freezer: the frozen beans had a more fragrant smell and taste initially, but after a day the frozen and room-temperature beans seemed pretty identical

- Darker roast beans stored at room temperature show oil; the frozen beans do not (until they have been defrosted, then same as room temperature beans).

- The frozen beans appear to have some structural change to them (I've seen this on two sets of beans). This is particularly evident for espresso: to get the same grind I've found that with my grinder I need to set the fine setting 2 to 3 clicks up (i.e coarser) for the frozen beans.

 

So at this point I would reckon that vacuum packed is good. Whether to store at room temperature on in the freezer is unclear (although I don't like the 'structural change').


Espresso Machine: La Pavoni Europiccola ERG, Grinder: Baratza Forte BG, ​Roaster: Gene Cafe CBR101

Share this post


Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.


  • About
    Coffee Forums UK is the UK's premier coffee forum Started in June 2008 by Glenn Watson, we now have more than 24000 mainly UK based members, and welcome more than 3000 members and visitors from around the world each day! With strategic investment and digital expertise from the Jackson Lockhart team (Tait Pollack and Adam Bateman), we are taking Coffee Forums UK to the next level, and are delighted to share the journey with you.

    New Members:
    We are often referred to as the friendliest forum on the web and we look forward to welcoming you onboard. Please read our Terms of Use. We stick by them, existing members please familiarise yourselves with them.

    Advertising

    Coffee Forums Media Kit

    Click Here To Buy Advertising Space 
    £100 p/m when paid yearly, up-to: 690000 banner impressions per month!

     

    coffee-subscription-mini.png

    Become a friend of CFUK
    Buy Us A Monthly Coffee (massive thank you!) 

     

    Donate / Sponsor

    Click Here To Donate (big thank you!)

    Get Your Supporter Badge Today (per year)

    image.png



    Coffee Forums Logo
     

×
×
  • Create New...