Storing beans under vacuum

[Journeyman]

Day 3 my time or from roast? I had the impression you are talking about from roast, but the beans I tried it with were 2 & 3 days old when I walked in the shop. They were 'squeezed' when I bought them but they weren't puffed out either.

Which means I got puffed bags from then up to 5 or 6 days from roast but not much after that. (as in after I squeezed them) I guess it might have happened mostly on the day I put them away as they were not sighted till 3 days later...

[TC]

I think you should all come clean and admit that they're actually Swedish weeney expanders and the whole idea of coffee is just a lame excuse.

[Yelta]

Not sure about 72 hours - The beans were about 3 days old when I bought them, so clearly they outgassed for longer than 72 hours.

I did say virtually complete JM, what I am saying is most of the degassing takes place in the first 72 hrs, try expelling all of the gas at the end of day three, then watch the bag over the next few days, inflation will be minimal.

[Journeyman]

Not sure about 72 hours - it could be a bit more, at least for commercially roasted beans. Not sure if they have different standards to home roast...?

After reading about the one-way bags I went and squeezed the bags I'd gotten recently (maybe 4 or 5 days previously?) and didn't get back to one of them for more than a week - it was still in 'squeezed' condition. Both bags had been partly inflated when I squeezed them, not to bursting but not a lot of crinkle room left. The beans were about 3 days old when I bought them, so clearly they outgassed for longer than 72 hours.

[Yelta]

My weekly 725 gram roast goes straight into a 1kg one way valve bag, I expel as much air as possible (squeezing by hand) before zipping it closed, the sealed bags shows no signs of inflation, after approx 3 days the bag has expanded quite a bit, however not even close to bursting point.
Seems to me most of the degassing occurs in the first 72 hours after roasting.
As an afterthought, cooler weather seems to affect degassing time, roasted my last batch Thursday last week, temp was cool, around 20c, bagged the roast and 24 hours later very little degassing evident, however a day later the bag had inflated significantly, regardless it seems that the release of gas is virtually complete by the end of the third day or 72 hrs, whichever you prefer.

[Thundergod]

I had a bag once with a faulty one way valve.
A week after roasting the ziplock had given way but the heat sealing held firm.
No burst but the bag was as tight as a football.

P.S. They didn't taste a week old.

[Darkfalz]

If you stuck them in an air tight bag with no one way valve just after roasting, I'd expect you might get a burst. But I've never got worse than a loosening of the vacuum bag (which, obviously, has specifically "stretchy" plastic to begin with) and obviously didn't vac anything newer than 1 week from roast. From what I've seen the one way valve typically requires some manual squeezing to force air out of it anyway.

[smokey]

Just watching the youtube clip with the Seattle girls testing bean storage methods... on the wall behind them is a sign, I want the free puppy!

"Unattended children will be given espresso and a free puppy."

[smokey]

Darkfalz, we are finding some evidence that other people do this with success, sweet. I was thinking again last night, an uncommon habit, and you mentioned it just now and reminded me. The beans de-gass CO2 which builds up and can burst containers and sealed plastic bags, so I use the vacuum one-way valve bags which I save up from my orders of roasted beans, and I also bought some from Beanbay as spares for when I get the Behmor and can roast to my hearts content - then freeze 'em

You must be a Canberrite as well, Cosmorex, Jindebah and Ona, all excellent roasters, thank the Gods and Goddesses we now have decent coffee in the nations capital

Just enjoying a Sunday morning with a week old popper-roasted decaf blended with Andy's 'organic espresso' as a latte, and I must say what a delight it is to enjoy real coffee especially when I have participated in creating it.

[Darkfalz]

Those Seattle Coffee girl did an experiment with frozen beans with fairly good results (look for the redux, not the first one where they don't bother to change the grind, get gushers and wonder why they all taste really sour)

These vacuum bags (well, it's on a roll, I "roll my own" bags hehe) are supposed to be freezer-burn and completely air tight. I've vac packed coffee before and if it's relatively fresh, the bags always get a bit puffy after a few days. I don't have this problem with my containers though because there's obivously plenty of space for CO2 to go.

Just had an Aeropress this morning with approx 3 week old beans that were just in an airtight ccontainer and it tasted pretty good, so I might be hard pressed to tell a huge difference from this extraction method.

I'd love to get into roasting but I have two good roasters nearby (Cosmorex and Jindebah, even LSR if I am desperate), so I can't imagine it'd be worth the outlay at this point.

[smokey]

I think that freezing soon after roasting would be a very good method of storage for long periods, especially as there is near to zero moisture in a freshly roasted bean. Your experience blend52 is just what I was expecting, thanks.

Things I would be watchful for are:-
1/ moisture seeping thru the packaging while it is in the freezer - maybe use a frost free freezer and good quality plastic bags
2/ if you roast and package in high humidity there will be plenty of moisture in the air to cling to the beans while they cool, and there may be some moisture clinging to the inside the packaging
3/ try to avoid roasting on days when it is raining - again this is to avoid excess humidity in the air that clings to your dry beans
4/ oxidation occurs at warmer temperatures so freeze your freshly roasted and cooled beans soon after roasting and cooling
5/ I am a little unsure about resting the beans until they have stopped out-gassing CO2, but I think this is not really an issue when storing for a few months at a time (please correct me if I am wrong)
6/ a good vacuum seal will remove excess air/oxygen at the very start of the freeze so minimal is left to oxidise while frozen
7/ oxidation will still occur in the frozen state - but it will be very very slow
8/ oxidation also adds some of the flavour we like, but we can leave this for when we open and thaw our beans later
9/ once thawed and brought up to room temperature the oxidation process will kick in rapidly so best to use quickly - the beans may last almost as long as freshly roasted but I doubt it as oxidation has been happening even while frozen, albeit slowly

I live in Canberra, its nice and dry and we get very little humidity, but when I lived on the coast the humidity, especially in summer, would be extreme on some days, I would avoid those days to roast. I hope this helps.

Darfalz, I would love to hear how your experiment goes too.

[Darkfalz]

I suspect vacuum sealed + frozen would be the best option for long term storage, even though the beans could likely never be used for espresso again, they might be great for an Aeropress. I suspect freezing would greatly reduce the gas release (particularly if beans are already ~14 days from roast) and the vacuum bags should keep air/odour/moisture out. Next time I have some excess fresh coffee beans I'll make up a few little pouches and freeze them and see how I go.

[blend52]

In roasted coffee beans the cells are damaged and therefore very open to oxidation. Water is made of hydrogen and oxygen, as it has the physical ability to soak into the dry bean it attacks /oxidises much more rapidly.

The 3 things that affect oxidation are the amount of oxygen available, exposure (ground or bean) and the temperature. Warm temps increase the rate of oxidation, and the more oxygen present the more there is to oxidise the cells. Once ground the surface exposure is enormous.

Thus, to keep roasted beans fresh longer we can keep them cool, away from water/moisture and reduce exposure to air both as a bean not ground and in an airtight bag..

Yes, temperature is a big factor.
There has been some well controlled trials ( blind tasting etc,.. HB forum) to asses the effects of storing beans in a freezer.
The conclusion was very favorable with deep freezer storage in sealed, airtight containers seeming to retain the "freshness" very well for several months .
I have occasionally done this with surplus roasts and been pleasantly surprised with the results.
Grinding straight from the freezer is also no problem and doesnt impact the result in the cup.

[smokey]

I have been doing some thinking because this is a real issue for everyone keeping roasted coffee beans. Its all about Oxidation.

Oxygen is a very unstable atom. It has 2 electrons which, instead of orbiting in opposite directions, orbit in the same direction making it quite reactive. When it contacts another atom / molecule it will rip electrons off them. This then makes that molecule unstable. This is the same process as 'free radicals', creating a storm of instability within the cell. Eventually this leads to inflammation and disease - and stale.

In roasted coffee beans the cells are damaged and therefore very open to oxidation. Water is made of hydrogen and oxygen, as it has the physical ability to soak into the dry bean it attacks /oxidises much more rapidly.

The 3 things that affect oxidation are the amount of oxygen available, exposure (ground or bean) and the temperature. Warm temps increase the rate of oxidation, and the more oxygen present the more there is to oxidise the cells. Once ground the surface exposure is enormous.

Thus, to keep roasted beans fresh longer we can keep them cool, away from water/moisture and reduce exposure to air both as a bean not ground and in an airtight bag.

This won't stop them going stale forever because the oxygen present will continue to oxidise, but slows it down.

One quick illustration - put metal in a flame and it will rapidly oxidise/corrode once exposed to air and moisture. The same goes with a coffee bean. Hope this helps.

[Darkfalz]

It's been a while since getting truly fresh beans, I get "fresh" ones from the supermarket which are usually about a month old (local roaster beans, sold through the supermarket). So maybe this was affecting my perceptions of the "rapidly downhill" as these were generally only good for a day two after opening packet in any case. Have gone back to a full vac with my actually fresh coffee and it's kept it much like the first day for four days now, full of volume and thickness.