# Preserving freshness - SCA article



## 9719 (Mar 29, 2015)

A good read on keeping your beans fresh

There is now universal acceptance in the coffee community that freshness has a huge impact on flavour and aroma. But what do we mean by freshness and, crucially, how do we measure it?

http://www.scanews.coffee/2018/04/18/preserving-freshness-race-time-25-magazine-issue-4/


----------



## 4085 (Nov 23, 2012)

On the Keep It Simple Stupid principle, I will give you some really good advice

DO NOT BUY MORE BEANS THAN YOU REALISTICALLY USE IN 2/3 WEEKS JUST BECAUSE THEY ARE ON SPECIAL OFFER.......there is no agreement on what the word fresh defines, anywhere in the world


----------



## 9719 (Mar 29, 2015)

dfk41 said:


> On the Keep It Simple Stupid principle, I will give you some really good advice
> 
> DO NOT BUY MORE BEANS THAN YOU REALISTICALLY USE IN 2/3 WEEKS JUST BECAUSE THEY ARE ON SPECIAL OFFER.......there is no agreement on what the word fresh defines, anywhere in the world


Dually noted, thanks for your insightful input, each to there own though, as everyone is allowed their own thoughts and opinions, mine being buy however many beans you want and do with them as you wish. I'm pulling beans from the freezer that have been in there well over six months and they taste as good as the day the went in there. KISS for me = rest for 10 days, freeze, enjoy as and when needed = happy days =SIMPLES


----------



## 4085 (Nov 23, 2012)

Oh dear me, the blind supporting the blind as usual.....you can do what you want, which is exactly what I do. If you do not buy an excess of beans then you have no problem. Never have been convinced on freezing but if it works for you then thats fine. I use beans 6 to 8 weeks past roast without the need to freeze or do anything else......maybe my tastebuds are not as refined as others, but who cares


----------



## 9719 (Mar 29, 2015)

dfk41 said:


> Oh dear me, the blind supporting the blind as usual.....you can do what you want, which is exactly what I do. If you do not buy an excess of beans then you have no problem. Never have been convinced on freezing but if it works for you then thats fine. I use beans 6 to 8 weeks past roast without the need to freeze or do anything else......maybe my tastebuds are not as refined as others, but who cares


Not a very pleasant opening line but 'water of ducks back' these days... I put up the post as I thought it to be of interest to forum members who can read it through and make their own conclusions as to what to do with the information contained within. As you so rightly point out WE CAN ALL DO AS WE WANT so shall we leave it there and agree to disagree and both do our own thing in our own little way? Other members may have their own ways of doing things, and I respect that, each to there own as they say.


----------



## Step21 (Oct 2, 2014)

********** said:


> A good read on keeping your beans fresh
> 
> There is now universal acceptance in the coffee community that freshness has a huge impact on flavour and aroma. But what do we mean by freshness and, crucially, how do we measure it?
> 
> http://www.scanews.coffee/2018/04/18/preserving-freshness-race-time-25-magazine-issue-4/


Posted this a few days ago in the thread on "bean maturing" in the Coffee Lounge.

Interestingly, one of the points raised was urging roasters to only roast to fulfill demand rather than speculatively overproduce. But there is useful info on degassing and the amount of CO2 in roasted beans.


----------



## 9719 (Mar 29, 2015)

Step21 said:


> Posted this a few days ago in the thread on "bean maturing" in the Coffee Lounge.
> 
> Interestingly, one of the points raised was urging roasters to only roast to fulfill demand rather than speculatively overproduce. But there is useful info on degassing and the amount of CO2 in roasted beans.


Apologies for putting this up again, I hadn't seen your original posting, yes there is interesting information contained in the article and if carefully read most should gain something from it.


----------



## DavecUK (Aug 6, 2013)

I read through it and the info on "degassing" and the amount of CO2 in roasted beans doesn't really make sense to me. It's an specific area I have been experimenting with for many years and unless I read it wrong, the science seems incorrect. They state


1-2% by weight of freshly roasted coffee of the CO2 is "trapped" inside the bean as if it's a little gas bottle. So from 10g to 20g per Kilo of roasted

They then talk about oxidation and also the good old 10C doubling the rate of chemical reaction for the processes which is correct.

Freezing slows id down, but if it was simply due to "trapped" CO2, freezing wouldn't make that sort of difference (based on the rate of reaction)

Lastly they vaguely state gas release is fastest uip to 48hrs after roasting and then tapers off


*
The ideal gas law (not my invention) states that at Standard Temp and pressure (STP) 1 mole of a gas occupies around 22.4 litres. At room temperature and pressure (RTP) this handy comes to about 24 litres. A mole of CO2 weighs44g which means 44g weight of CO2 will occupy 24 litres at 1 bar. From their own statement 1-2% of the coffee is CO2 by weight. So from 10 to 20g of CO2 in 1kg of coffee. This CO2 would occupy from about 5.5 litres to 11 litres at RTP. This is not up for debate, it's not a guess it's just science based around their own numbers.*

So 430g of coffee (medium dark roasted) should have around 2.5 to 5 litres of CO2 after a week or two, from what the SCAA says. The only problem is...it doesn't. Experimental evidence does not confirm their theories. In fact about 10 or 11 times less CO2 than they estimate is produced. This disparity is because they have made a set of assumptions that are not correct. Of course I don't expect anyone to accept what I have said, even though you may be prepared to accept what the SCAA say, because it's the SCAA, so I offer evidence.

The Video shows a sealed bag (no valve) it's a much thicker version of the Mylar and foil used for Helium balloons and does not allow diffusion or leakage of any sort. Within is 430g of Medium Dark roasted coffee roasted just over 3 weeks ago. The bag is floppy and under no pressure and almost all air was removed from the bag before sealing, so there may actually still be some residual air in their (minus the O2 portion of course, so mainly Nitrogen). Do you see 2.5 litres to 5 litres of air in the package (1 - 2% CO2 by weight) as the SCAA claim?


----------



## DavecUK (Aug 6, 2013)

This captcha thing quite often gives me an empty screen after it comes back to a post. So I couldn't embed the video directly in the post above.


----------



## 9719 (Mar 29, 2015)

DavecUK said:


> I read through it and the info on "degassing" and the amount of CO2 in roasted beans doesn't really make sense to me. It's an specific area I have been experimenting with for many years and unless I read it wrong, the science seems incorrect. They state
> 
> 
> 1-2% by weight of freshly roasted coffee of the CO2 is "trapped" inside the bean as if it's a little gas bottle. So from 10g to 20g per Kilo of roasted
> ...


There's always one......bet you were that annoying little sod always sat in the front row with arm permanently raised going please sir/miss...

No offence meant ^^^

Seriously I have to bow to your superior knowledge on the subject. Myself I don't take as gospel anything that's written be it the SCAA or anyone else, I'm always happy to read and digest articles and then come to my own conclusions be those right or wrong in others eyes.

I didn't understand much of what you wrote way tooooo super scientific for my little brain but that video, now that I do understand. Although I do have to thank you for reminding me to go deal with that little  of a mole digging up our lawn


----------



## DavecUK (Aug 6, 2013)

********** said:


> There's always one......bet you were that annoying little sod always sat in the front row with arm permanently raised going please sir/miss...
> 
> No offence meant ^^^
> 
> ...


Actually I wasn't, I was usually getting quite bored in class and had little interest in answering teachers questions.

It's not really any superior knowledge, I don't know for sure what's going on with coffee after roasting, but by my own experimentation over years, I do know that what the SCAA state, doesn't make sense, or fit the observations. I'm not even saying my observations are better, but I am one of the fiew packing into totally sealed bags. I do this because I have the luxury of not needing to ship coffee by post. When shipping coffee by post, with no valve the bags all puff up occupy more space and exert pressure on external packaging. I suppose my worry is how many roasters will take as gospel what the SCAA say....

P.S. The coffee also stays fresher when in a totally sealed bag with no valve.


----------



## 9719 (Mar 29, 2015)

DavecUK said:


> Actually I wasn't, I was usually getting quite bored in class and had little interest in answering teachers questions.
> 
> It's not really any superior knowledge, I don't know for sure what's going on with coffee after roasting, but by my own experimentation over years, I do know that what the SCAA state, doesn't make sense, or fit the observations. I'm not even saying my observations are better, but I am one of the view packing into totally sealed bags. I do this because I have the luxury of not needing to ship coffee by post. When shipping coffee by post, with no valve the bags all puff up occupy more space and exert pressure on external packaging. I suppose my worry is how many roasters will take as gospel what the SCAA say....
> 
> P.S. The coffee also stays fresher when in a totally sealed bag with no valve.


I know that feeling, only a couple of teachers capable of keeping our attention one of whom had an extremely accurate right arm when launching a blackboard rubber!

Perhaps superior knowledge was the wrong wording, making you sound as if your otherworldly  Maybe, vast experience, would be a more correct? Which as always I look forward to you sharing with us lesser beings


----------



## DavecUK (Aug 6, 2013)

********** said:


> I know that feeling, only a couple of teachers capable of keeping our attention one of whom had an extremely accurate right arm when launching a blackboard rubber!
> 
> Perhaps superior knowledge was the wrong wording, making you sound as if your otherworldly  Maybe, vast experience, would be a more correct? Which as always I look forward to you sharing with us lesser beings


I doubt my experience is vast, most of us have certain *narrow lines of experience* in areas we have an interest in. The important thing I suppose is our choices of whether to question something and possibly find out more about it, even experiment with it. I have an interest in making good coffee, so an interest in all things that go with that, such as bean, roaster, machine and grinder.

Sadly, I actually share very little of what I do, partly because I am too lazy to do so. That laziness is why stopped really updating the Coffeetime Wiki many years ago and my research on packaging of coffee, roasting, water, cleaning techniques, machine maintenance, engineering tricks, work with Kruve sieves, manufacturer service manuals, machine video and photo library, hacks and improvements etc.. etc.. have not been shared. In a sense I have got out of it what I needed to to improve my own coffee experience, that's what's of primary importance.


----------



## wings_n_dat (Dec 17, 2018)

thanks for this


----------



## the_partisan (Feb 29, 2016)

It could also simply be that as the CO2 concentration builds up, the rate of release gets slower and slower and almost stops? Or that unless the coffee is ground some CO2 is simply not able to escape. I've seen vac packaged commercially ground coffee which seemed to bloom very strongly when brewed, indicating there was still lots of CO2 left in the beans.


----------



## DavecUK (Aug 6, 2013)

the_partisan said:


> It could also simply be that as the CO2 concentration builds up, the rate of release gets slower and slower and almost stops? Or that unless the coffee is ground some CO2 is simply not able to escape. I've seen vac packaged commercially ground coffee which seemed to bloom very strongly when brewed, indicating there was still lots of CO2 left in the beans.


No, not at all...I've provided evidence, do you have any actual evidence for your thoughts?


----------



## the_partisan (Feb 29, 2016)

You say that "So 430g of coffee (medium dark roasted) should have around 2.5 to 5 litres of CO2 after a week or two, from what the SCAA says" but from my reading of the article this is not what is stated. It just says 1-2% of the beans can be CO2, but rate of release slows down after 48h. It doesn't say anything about how long it would it take to get all the CO2 out of the beans or a specific rate of release when beans are not ground.

The full paper referred to is here: https://pubs.acs.org/doi/pdf/10.1021/acs.jafc.7b03310 . This is how the 1-2% measurement was done:



> In previous works, the total amount of gas or CO2 and the degassing rates from roasted whole beans and ground coffee have been measured using three different analytical approaches:
> 
> (i) The pressure increase was measured in a closed container during storage of roasted beans and related to the amount of released gases.
> 
> ...


----------



## grumpydaddy (Oct 20, 2014)

Thanks for this thread. I somehow missed it at the time.

I guess we all take as read certain info, depending on source, until or unless our observations make us question said info.

For example: In the beginning I bought beans by the Kilo and bags with valves to decant into before sealing in jars and I look back and think "why?". I also noticed that I got lots of beans from different roasters and I think that only once did I see a single bag that was to any degree inflated by gassing beans.

These days I try to vacuum pack into 3-4 days usage portions as soon as I get them. I get it that possibly the vacuuming process might have a bearing on the rate of degassing but I have yet to see any packed beans appear to have added volume to the package.

Now maybe I missed something about the structure of a coffee bean not allowing escaping gas or something equally as unlikely but it does make me question everything to do with gas content of beans.

Yes, the purists among you might think what I do is sacrilege but it works for me and it allows me to use my favourite beans over a period longer than their season and the only person that I have to satisfy is me.


----------



## DavecUK (Aug 6, 2013)

the_partisan said:


> You say that "So 430g of coffee (medium dark roasted) should have around 2.5 to 5 litres of CO2 after a week or two, from what the SCAA says" but from my reading of the article this is not what is stated. It just says 1-2% of the beans can be CO2, but rate of release slows down after 48h. It doesn't say anything about how long it would it take to get all the CO2 out of the beans or a specific rate of release when beans are not ground.
> 
> The full paper referred to is here: https://pubs.acs.org/doi/pdf/10.1021/acs.jafc.7b03310 . This is how the 1-2% measurement was done:


It just says 1-2% of the beans can be CO2 = 2.5 to 5 litres of CO2 for 430g of coffee....sorry but that's just chemistry and gas laws, I'm not making it up. I also read the full paper a while ago. *I think you are just going to have to get from it what you want to believe*, but know that papers vary in how good they are and just because it's published doesn't make it right. During my degree, much of the course was using scientific papers and it was important to choose the right ones and learn how to critique them properly, sifting the wheat from the chaff. It's also important to trust established science and have well constructed experiments that validate theories. The simplest experiment I had totally disproved the SCAAs conclusions. Of course I'm not in business or getting research funding am I....so I have nothing to gain.


----------

