Keeping Beans Fresh

[MrJack]

The vac effect happens when you return to ground and the volume in the bag decreases due to atmospheric pressure.

When you say the "vac effect occurs", you mean the bag takes on the appearance of a vacuum packed bag?

[beabeabeaner]

Here is my theory.
Ageing is oxidation. Oxidation needs oxygen. So, use bag with valve and remove as much air (20% oxygen) as possible from the bag after heat sealing the bag. (you can suck on the valve with a vacuum cleaner or just by mouth, quite an interesting sensory experience!) As the beans degas in the bag, the remaining oxygen becomes diluted by the CO2 - which is inert from the oxidation point of view. As the valve releases the gas in the bag, more oxygen gets washed out. Less oxygen, less oxidation.
In airplane luggage (low pressure) the degassing happens more quickly, diluting and washing out the oxygen faster. This is good. And the coffee aroma in your luggage is amazing. The vac effect happens when you return to ground and the volume in the bag decreases due to atmospheric pressure.

Swing top bottles sound very difficult to use. Keep for homebrew.

[MrJack]

I wonder how swing top beer bottles would go (after all, their purpose is to retain CO2 and exclude light).

[noddyc43]

Yes will be interesting to see the results of the vaccum pack. I wonder also In that environment how it works as the beans continues to release CO2 and how that affects it being in a fully enclosed environment. Keep us updated Dragun

[Thundergod]

I'll repeat for the newcomers -

I once had a bag with a faulty valve and the effect of it not being able to degas was a slowing of aging.

[Yelta]

I reckon vac = degas and accelerated ageing

I reckon you may well be right.

[TC]

All you need to do is fly with 2 bags of fresh and 1 way valves- Tape over one valve, but not the other = instant vac pack. I have done it and there was a difference at the other end. I reckon vac = degas and accelerated ageing

[Dragunov21]

Will do

also wondered what affect the vacuum will have on the beans, will it in fact draw the oil to the surface of the bean more rapidly.

I'll be doing some more roasting over the next few days, so I'll split a batch in half and vac one half, with the other half in a ziplock.

[Yelta]

Let's see what they look like in a week...

Have often wondered about vacuum packaging.

Will be very interested to see the condition of the bags in a week (prior to opening) have also wondered what affect the vacuum will have on the beans, will it in fact draw the oil to the surface of the bean more rapidly.

Good post Dragunov, keep us in the loop.

[Dragunov21]

Let's see what they look like in a week...

[noddyc43]

I use a glass jar with a one way valve. You can push the lid right down to the beens similar to a one way valve bag. Looks the part next to the grinder and coffee machine as well! Got it off a kickstarter campaign.

[Dragunov21]

Hmmm, maybe I've got my wires crossed then, carry on.

[Barry O'Speedwagon]

Cosmorex's bags (as available in Canberra) are not vacuum packed (certainly not the ones I've purchased). They have fairly recently changed the art work on the bags used for some of their blends, and I haven't tried any of those so I can't comment absolutely.....but when I saw them at the Fyshwick shop nothing looked like it was vacuum packed to me. The bag I got as a freebee when purchasing my M2M about 2 months ago was definitely a 250g one-way valve bag. They don't IIRC, allow for re-sealing after opening.

[Dragunov21]

Honestly the biggest reason I'm giving this whole idea the time of day is because I'm almost certain that either Cosmorex or Campos (and I think it's Cosmorex) were doing vaccum-packed, non-valved bags. Perhaps someone can confirm if they've ordered from either?

[chokkidog]

In any event, do as you wish. Store your coffee in the freezer, in vacuum bags, in glass jars or whatever. However, as a commercial roaster who manages to roast coffees that de-gas a huge amount of CO2, I will happily stick to bags with one-way valves and, hopefully, none of my coffees will ever see the inside of a freezer.

Absolutely Vinitasse! I sometimes get the impression that some line up 10 empty milk cartons next to a bag of coffee and go;..... " I don't think that'll fit "

What needs to be factored in is that a one way valve ( and I have only ever known of one failure ) will only release gas once release pressure is achieved.

If the gas in the ullage space of the bag is under pressure, it is being compressed, to a degree, which then alters how we should

conceptualise the volume of CO2 that is outgassed.

So, if a 500 gm of medium roasted coffee outgasses 2-3 litres of CO2, some is compressed inside the bag while some is slowly being released to atmosphere.

Having this sort of approach made it easier for me to understand the physics and get a handle on why the gas volumes seem

disproportionate to the amount of coffee, 'in the bag'.

The author's note about freezing coffee I included because, to me, it throws some doubt over his notion of best practice, at least

enough for the whole shebang to be discussed rather than left unquestioned.