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ljguitar
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Posted Tue Mar 23, 2004, 10:01am
Subject: Re: Vacuum Canisters
 

Dechelbarg Said:

---one of the reasons I'm interested, is that I like to hang onto some beans that aren't my normal cup -- I want a given taste from time to time.

Posted March 23, 2004 link

If you really need to hang onto some beans for storage from time to time for up to 6 weeks, then just toss em into a jar or vacuum pack them, or double ziplock them and freeze them within an hour of roasting before degassing begins.

The freezer will arrest the degassing process till you thaw them. This is a proven method, and is used by roasters when they have to roast specialty coffees in larger quantities than they can sell immediately.

L  a  r  r  Y

<°)))><

 
L  a  r  r  Y          J

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pcharles
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Posted Fri Mar 26, 2004, 9:49pm
Subject: Re: Vacuum Canisters
 

I've been busy looking for a good, and reasonably priced, place to store 4-8 ounces of home roasted coffee ready for use in a day or so. I'd like to have a couple of these so that I can roast a couple of varieties and maybe blend them later for brew experimentation.  I'm pretty interested in the Vacuvin system or even the Tilia system because these all have one-way valves designed for sucking air out.

Most people seem to talk about these systems in conjunction with the pumps, but has anyone tried using them without vacuum? It seems to me that if you get one just large enough for your home roasted beans and then let them degass without the vacuum, the one-way valve should allow gas to escape without losing too many other beneficial aromatics.

Anyone tried this? Does it even sound reasonable?

Does anyone know where other degassing canisters can be purchased?

Have many people degassed in foil lined bags similar to those we purchase fresh roasted coffee in?
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pcharles
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Posted Fri Mar 26, 2004, 10:21pm
Subject: Re: Vacuum Canisters
 

With vacuum bags, you are doing something very different to vacuum storing in a canister.   In a canister with a large head space I believe the contents will come to a gaseous equilibrium pressure (vapor pressure). If the container is strong enough, eventually the vapor pressure should prevent further degassing. If not, then ......bang, your lid pops off.  This suggests that a strong glass jar such as the Mason bottling jars or something designed for presure, with a screw or well fixed lid, will work fine to prevent explosion. Then when you open and close the canister, to remove some beans, gas pressure is released and the process can start again. So you can control staling.

If you create a vacuum in the canister, a phenomenon known as LeChateliers principle occurs and whatever is left in in the canister under vacuum will try and return the pressure in the canister. This probably means that volatiles will evaporate and so stale the coffee.  In the case of a Foodsaver bag you are vacuum packing in a different way. You are removing most of the head space by sealing the bag around the beans. I would guess that this limits the beans ability to degass, because these bags are very very strong and there is very little space for expansion.  Thus the vapor pressure quickly reaches equilibrium and degassing and loss of aromatics is reduced.

If you us a vacuum container, but do not evacuate, in theory, the container will reach equilibrium and only degass further when the internal pressure reaches the pressure of the one-way valve. This should allow gas to escape, but prevent oxygen returning and reduce the loss of volatile oils.

Something to consider is that vacuum packing coffee you plan to open more than once a week is probably a complete waste of time. Every time you open the can, you not only lose precious aromatics you let in more moisture and air. Worse still, by vacuum sealing the coffee you open the pores, which then fill with air when the vacuum is released. If you have kids and want a bit of fun. Put a couple of Marshmallows in a vacuum jar and evacuate it.  That is what happens to the beans, except not as drastic. . .  . . . .



Just a thought.
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pcharles
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Posted Sat Mar 27, 2004, 11:20am
Subject: Re: Vacuum Canisters
 

Just back from WalMart. I looked at some of the Black and Decker and Foodsaver canisters. Both of them have loose-fit lids that rely on the vaccum for a tight seal, so maybe you could make one from a mason jar.  It seems to me that if you drill an ultra fine hole in the top of the metal mason lid and then sticky tape a square piece of flat rubber over the hole, you could create your own one-way valve. Since the rubber is only attached on two edges gases could escape under pressure, while preventing air from entering.


What I found really interesting was the freshness ratings:

They claim that under their vacuum, formerly canned bean coffee will stay fresh for 2 years compared to 2 months in a normal container. They also claim that ground coffee will keep for 3 years compared to 2 years for canned coffee.  

If people are finding that their bean coffee loses vacuum overnight, either someone has re-evacuated the coffee each day or they have not actually tested the 2-years. OR the beans were so dead and stale that they contained nothing to suck out anyway.

Anyone want to comment on this??? ;-)
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da_russky_007
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Posted Thu Jun 10, 2004, 12:59am
Subject: Re: Vacuum Canisters
 

Very interesting thread.  I do not roast my own coffee, but I buy it freshly roasted. So storage is definetely of a concern to me. I am glad to see some chemistry contemplation from Paul Charlesworth.
I am currently pursuing a master's degree in chemistry and tech some labs as well as tutor in chemistry at Idaho State Univeristy. My specialty is analytical chemistry. I have just posted some of my thought on chemistry behind pressurized portafilters and extraction in the following thread: click here
I am just out of surgery so I did not double check the validity of my statements. So maybe you guys, if you have any desire, could tell me what you think of what I said there.

Meanwhile I would like to express my opinions of vacuum sealing beans, both from practice and theoretical knowledge.

first, i think, it is understood by most people that the essence of the coffee beans so responsible for the aroma and taste we are so interested in preserving are the volitile organics. Volatile means they, so to say, volitilize or 'evaporate' very fast. I like to judge freshness of beans by smell. Big part of what we are smelling in fresh coffee are those volatile compounds. If we let the coffee sit forever, these compounds volatilize or 'go away', and we are left with some blend stale taste... something like those beans in a parfume sections of malls.

before we go into discussion on storage, we need to first target the factors contributing to deterioration of those volatile organics.

the most popular factors are sunlight, moisture and oxygen.

sunlight is basically the high energy UV radiation, which attacks the bonds in the molecules of the organics and facilitates  their breakdown.

moisture, i pose, primarily destroys texture, and provides good environment for some microorganisms that you don't want 'living' in your beans, since the results of their bioactivity... well i am not going to go there for now.

finally, oxygen, THE beast. Oxygen gas is a diradical in its essence and does a pretty darn good job of attacking those precious bonds that constitute our lovely volatile organics. It destroys anything... that's why oxyclean does a pretty darn good job cleaning - your stains (which are colored) have that coloration that make it so unattractive, partially because of conjugation (a funky way bonds in a molecule get together) and oxyclean is more likely to break those bonds and alas!, no conjugation, no color, no stain... (well... that's just part of the story, i am not going to waste time talking about all the ways it works, but main thing is that it works because of the oxygen).

so we definetely need to get rid of the oxygen (together with sunlight and moisture).

I own a Pro II moder of FoodSaver, so next I will mix some first-hand experience with theory. I have vacuum sealing my beans in one of the supplied canisters. That, i think, works far better that just storing the beans in an airtight canister, or in the freezer. I get into my vacuum coffee bin several times a day and consequently seal it again after every use. I noticed that beans stay fresh for quite a while, say a month, when beans in a just airtight canister go flat in less than a week, even if frozen (not to mention that moisture left over in the beans upon freezing seems to do something to it that... just doesn't smell or taste good).
Now... beans do stay fresh in sealed bin, but... how fresh? obviously not fresh enough, that after two months of use i saw it fit to look up a thread on this site to see what other folk has said.

Despite the fact that vacuum sealing bean in a foodsaver canister gets rid of most oxygen and moisture (and everything else with it :) there is still something that it lacking. So... it's time to use some of my chemistry and physics knowledge to look for a solution.

i am now going to look into what is happening to our precious organics and the beans as we vacuum seal them in a bin (now there is a great difference between sealing in a bin or a bag. i will conteplate on  bag sealing later in this post).

When talking about sealing something in a vacuum, a picture comes into my mind from that movie with Arnold Swartzeneger on Mars, when he ends up in the 'vacuum' atmosphere of Mars and his eyes start bulging out and skin puffs up etc... (sorry, it's a pretty nasty picture, but it makes the point). What heppens is that things like coffe beans, liquids, marshmellows etc. have certain amount of dissolved gas that on the inside of the object is equal or close in pressure to the atmospheric pressure. As the atmospheric pressure is pushing on the object, the pressure of the gas inside is pushing out. The both equal each other. So when we remove atmospheric pressure, the gast on the inside is still pushing out, but in vacuum it has no resistance and therefore is going to escape the object faster. You can see it if you vacuum seal any liquid, you will notice bubbles escaping the liquid. Now it is not as easy in case of vacuuming container with gas trapped inside of a coffee bean or any other rigid structure, like marshmellow (or a piece of meat for example). If you vacuum seal a marshmellow, you will see that it will blow up about three or four times in size.
This has two implications in regards to a coffee bean. First, the gas inside of the bean will try to escape with more that atmospheric pressure 'upwards'. The gas inside of the bean is full of those volitile organics. During roasting, high temperature of roasting process facilitates volatilization of organics, and they end up being traped in empty compartments inside of the bean expanding and mixing with other gasses. All that previous aromatic goodness, will be forced out of the bean when you vacuum seal it... together with oxygen and moisture. So although you minimize damage by oxygen and moisture, at the same time you are pumping out the volatile organics. In my experience, it ends being an ok trade off... well better that just letting oxygen eat away at your organics. But we expresso geeks are not people who feel comfortable with any trade offs. We need the best results. Ok... I sidetracked.
Back to the second implication of gas escaping the bean. Kind of like gas on the inside blowing up a marshmellow, that gas inside of the bean will also push on the inside walls of the bean and, in my opinion, some damage to the rigid walls is inevitable. The micro fractures might not be seen to a naked eye, but i am sure that cracked walls also leek some more volatile organics... something similar to what happens after grinding, just on a smaller scale.

Ok. Next point. What about freezing? Well, once the oxygen is out together with the moisture, why not? Decreased temperature is know to slow down chemical precessess, including those of decomposition, or physical processes of evaporation. I think the reason why most people don't like to freeze their beans, is because they still have moisture and oxygen... so baically what you do is make a 'beansickle' with oxygen trapped inside that just does more damage. It's kinda like getting a fresh strawberry, freezing it, letting it sit in the freezer for a week, and then defrosting it and comparing it to a fresh one.... yeah, that would notbe a pretty picture. One advantage of a bean over a strawberry is that in naturally doesn't have moisture in it (at least not after sun drying and roasting it), so if you expell the moisture and O2 out, the freezing process should be pretty dry, which means good and clean.

Ok... there must be a solution to this whole thing. What is it? well... i know i am not going to infuse my beans nitrogen gas, cuz i simply don't want to bother - too much work, money and a gas tank would take too much space. But I think that vacuum sealing in a bag could be a great solution!

I have actually seen ground coffee sold in vacuum packaged bags. I assume a company would not bother selling ground expresso vacuum packaged if it wasn't worh a thing. So... let's look at some science!

So when we vacuum seal beans in a container, the problem is that we loose that atmospheric pressure that keeps the gas in. But alas! if we seal beans in a bag, the walls of the bag would collaple under atmospheric pressure, and thusly :) we would still have a force counteracting the inside gas pressure, keeping that gas in. Cool huh?: no moiture, oxygen, no atmorpheric pressure loss. That sounds like a bargain! Plus, you should be able to freeze the bag on top of it and your coffee would last even longer.

I would like to compare the two sealing method, using an illustration of, say, marinading a steak.
If you put your steak in a canister and suck the air out, you will see a lot of the juice come out. Break the seal and you will end up in a dry steak and juice all over. Now if you take that same juice and steak and put them in a bag and seal them, you will see that the vacuum will cause the walls to collapse and atmospheric pressure will force the juice back in the steak. That's why it's better to marinade a steak in a bag. Thus the vacuum will force the juice in the steak. If you try to marinade a steak in a canister, you will just end up having more marinade. My all time hero Altom Brown from the show Good Eats on food network would wholeheartedly agree with me on this poing. Well... the similar concept applies to sealing beans.

Of course there are some issues involved in sealing beans in a bag. First, it will be more of a pain in the butt, because you will have to cut the bag every time. Bags are harder to handle. It costs money to get new bags etc. But! If we are smart enough to master the art of pulling the perfect shot, roasting coffee and so on, I am sure we will be able to come up with some kind of clever modification that would make bag sealing more convenient. In fact I am going to try to develop one here pretty soon. I have already figured out how to use zip-lock bags in them foodsavers (it ends up being twice or thrise cheaper).  I am sure I could come up with something else.

So you guys tell me what you think of what I wrote and whether you are interested in developing some convenient vacuum bag storage for everyday use.

Thanks a lot for reading this post.

Cheers,

-Yegor

PS I aposogize for any spelling mistakes of any sort. I am just out of surgery today, so i am too tired to proof-read this.
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DEchelbarger
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Posted Thu Jun 10, 2004, 6:30am
Subject: Re: Vacuum Canisters
 

Yegor:

thank you so much for your analysis.  I saved it.  There is plenty to consider in your post.
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Yooperjohn
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Posted Thu Jun 10, 2004, 8:15am
Subject: Re: Vacuum Canisters
 

Yegor,   verrrrrrry interesting stuff!!!!  Gooooood Post!!!!   John
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DEchelbarger
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Posted Thu Jun 10, 2004, 8:41am
Subject: Re: Vacuum Canisters
 

Yegor,

What is your take on these questions:  Do beans degas in a vacuum canister?  In a vacuum bag?  In a vacuum bag frozen immediately after roasting?  

Thanks again for your contribution.
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da_russky_007
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Posted Thu Jun 10, 2004, 12:19pm
Subject: Re: Vacuum Canisters
 

First of all, thanks for reading what I wrote. I kinda got fired up writing about it. I am actually thinking about dong some heavy-duty theoretical research on the topic (finding studying all kind of reasearch other people have performed and putting it all together). Then I am actually thinking about making some 40 minute seminar next semester on the topic if my chemistry department approves.

DEchelbarger Said:

Yegor,

Do beans degas in a vacuum canister?  In a vacuum bag?  In a vacuum bag frozen immediately after roasting?

Posted June 10, 2004 link

Here are my thoughts on the matter. I will write a little story about one my experiences, so if you don't want to read it, just skip this paragraph. It's kind off funny, but the first day I purchased  my FoodSaver, I also stopped by the local coffee shop to pick up some freshly roasted coffee. I bought two blends and vacuum sealed both of them in the mason jar attachment. One of them I did not tough for a couple of days. Another one i used daily. How disappointed I was to find out that the jar with the blend I didn't tough for a couple of days, was completely unsealed and, to be honest, all the fresh smelling aroma was gone too. After a little of thought, I realized though, that since the jar was pretty much full of beans, the degasing process pretty much filled all the vacuum so that the internal jar pressure equaled the atmospheric and the vacuum seal was broken, and more air came in.

After beans are roasted, the gas inside of the beans I trying to get out. The things that are stopping it are atmospheric pressure and inside walls of the bean. Another thing that facilitates the gas escaping the bean is diffusion. I like to think of diffusion as a riverdance: the molecules are bumping into each other and trade partners and thus disperse throughout each other. Actually even such hard structures as metals undergo diffusion. One time they pressed gold against some other metal and left it alone for several years. The result was that the metals fused into each other. The gold plate left in the air, not touching another metal, did not diffuse into the air. In any vacuum seal, the diffusion is minimized. But I don't think we have to worry about diffusion a whole lot.

In a vaccuumed canister we take out one of the main factors that keep the gas inside of the bean - atmospheric pressure. So beans will degas faster in a vacuumed canister rather than a nonvacuumed one.

In a vacuumed bag on the other hand, the effects of atmospheric pressure are somewhat preserved, because the walls of the bag collapse under atmospheric pressure and push on the beans. There are still cracks in between the beans left with vacuum. Those will add up to a very very small effect of what happenes in canister (except canister has a huge amount of that space - and that space is what we don't want). But I would think that i don't think it would be an that much of an issue.

So what if we vacuum seal and then freeze the beans. According to the Gas laws (that we study in General and Physical chemistry), as we decrease temperature for a gas it volume and pressure are going to decrease. That is a raelly good thing. Because if the volume and pressure of the gas inside of the bean is going to decease, our lovely gas is not going to be as eager to escape and stay inside of the bean. And since the the bag is completely sealed off, not moisture or odors form any stinky freezer should come even close to the beans. On top of all that, decreasing temperature decreases potency of the volatile organics. I remember an organic chemistry lab I used to do research in. Well, there are some volatile organic compounds that are so volaitle that they seep out of even tightly closed containers. In case of organic chemistry most volatile compound stink so bad, that rotten egg, meat and fish smells don't even come close in comparison. So, these compounds we usually stored in a fridge. And guess what? Our lab was (and still is) the best smelling organic lab out of very very many. All because of refrigeration.
Same thing happenes in case of freezing beans with them volatile organics. Except, I would want them to come to room temperature before I would grind and extract them.

So all that theory. If would actually be a good idea to vacuum seal freshly roasted beans, freeze it and see what comes of it. I will definetely try it after my knee heals and I can finally move around :)))

Cheers,
-Yegor
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DEchelbarger
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Posted Thu Jun 10, 2004, 5:16pm
Subject: Re: Vacuum Canisters
 

Yegor,

Thank you once again for your reply.  I once vacuum sealed in a bag some fresh garlic.  In a few days I had a garlic gas balloon.  When I popped it, you could not believe the smell.  I guess things do degas in a vacuum!
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