Bean de-gassing, accelerated aging and vaccum containers

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#1: Post by Vindibona1 »

I have a subscrption of medium roast beans that come every week. While the box is not marked with a roast date, based on the "best by" dates I cannot imagine that the beans are more than 5 days off the roaster. The new beans stay in the boxes they were shipped in and sit in my cabinet for a few days while I finish up the last batch.

I thought I was doing something good to keep my beans fresh as I worked through them as I bought a vacuum container that pumps the air out. It has a little post that gets sucked down when there is vacuum pull on to show that most of the air had been sucked out. However, especially with new beans, after 24 hours or so the post is sticking up indicating that there was no longer vacuum pressure inside the container. [Shortly after I got the container I found out the hard way that all the pressure had been released as I grabbed the lid and spilled 12 oz of beans all over the floor :( ].

I have to assume that the release of the internal vacuum pressure is due to bean de-gassing. Yes/no???? I make that assumption because as the week progresses there remains some residual vacuum each day...

....HOWEVER... What I am wondering is if the vacuum container is causing the beans to de-gass more quickly than if I just left them in an air tight container, like an old empty Illy coffee can? The reason that this is a concern is because it appears that my "dialed in" recipes only work for a day or two, and consistency from day to day is almost non-existent, which frustrates the heck out of me as my routine is as repeatable as humanly possible.

Does the vacuum container accelerate bean aging, and should I consider abandoning the vaccum container in lieu of just an air tight one?

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#2: Post by ira »

There is a storage device that keeps beans under pressure in CO2 that seems to keep beans fresh for extended time periods, coffee freshness system or similar. So one could assume a vacuum might not be optimal.


#3: Post by jpender »

You can find old threads on this forum where this is discussed (like this one). One theory is that repeatedly vacuuming the beans results in the loss of aromatic volatiles. I have not seen good data to support this idea. I doubt that a careful search will turn up anything definitive. Confusing the issue is that not all vacuums are the same. Your device probably does not pull anything close to a hard vacuum. Maybe it removes 70% of the air, something like that. Maybe it leaks too.

Getting the oxygen level down to 1% or less has been shown to be quite effective. The Coffee Freshness System uses CO2 to displace the air and achieve that. It works. But it's not inexpensive.

The other very common approach to slowing down coffee degradation is to remove the energy in the system by storing the beans at a reduced temperature (freezer or refrigerator). That has also been shown to be effective. And it's inexpensive.

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#4: Post by coffeedog »

Try testing the seal/vacuum without any beans. I had one container lid where the little plastic plug just wouldn't hold a seal anymore.
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#5: Post by cafeIKE »

Freeze in 2 to 3 day requirement sized hermetic jar/tin/package upon receipt or at optimal brew age.
Remove from freezer as necessary.
Perfect shots forever...
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Vindibona1 (original poster)

#6: Post by Vindibona1 (original poster) » replying to cafeIKE »

I've got a couple available Illy cans that aren't doing anything. I should segregate the batch that I just opened today and freeze some and do A/B comparisons throughout the week.

As I think about it, a cannister that adds pressure might be better suited than one that creates a vacuum. I dunno. What I don't want is overyly fast outgassing. This last batch of beans that I just finished really changed quickly, not only requiring a finer grind throughout the week, but the shots were better tasting later in the week when I ramped down the flow through the pull. I haven't pulled any shots with the new batch yet. It will be interesting to see what needs to be adjusted from the old batch to the new, then over the week.

Vindibona1 (original poster)

#7: Post by Vindibona1 (original poster) »

New batch of beans this morning, left in the vacuum container overnight. I did two shots, the first with 17g with 36mL target output, hit with the WDT, then the distribution tool, then tamp and straight shot with flow valve open in one position. 26 seconds. Pretty good actually. Second shot was identical except that I closed the flow control at the start (2.4 mL/sec) until first drip, then opened it up fully (6.4mL/sec), then gradually closed it again after the 10mL was in the cup. 28 seconds. Rounder, smoother more balanced than the first shot. Better than the old batch of beans I had just finished.

New beans arrive every Thurs, Friday or Saturday and usually sit for a couple days before I get to them. It will be interesting to see how this remains constant or changes throughout the week.


#8: Post by Phobic »

you might be trying to use your beans too soon after roasting.

better to wait until they are fully off gased, this will help with your consistency issue - depending on bean and roasting level this could be 5-7 or more days.

There's maybe not as much rush to drink your beans as you think so don't rush it.

If you find you're running out before they next batch has off gased simply buy an additional bag, that will give you time to off gas the next bag properly before you start to use them, from then on you should be in a better place where the beans have time to off gas fully before you need to use them

Vindibona1 (original poster)

#9: Post by Vindibona1 (original poster) » replying to Phobic »

Typically the new arrivals sit in the cabinet for a few days as I finish off the previous batch. My concern isn't the beans not having degassed, but are experiencing too quick a change while in a de-pressurized vacuum container. I started this latest batch on the 19th and at this point I'm happy with the end result and am playing with ramping down the pressure with the flow control after 10g is in the cup. 30 second pull just moments ago that I prepared for Americano 1:1 espresso and hot water.

I've been having pretty good success with 17.5g coffee into 36mL output, 200°F. Starting full on water about 6.4mL/sec with about 8bar pressure. At around 10 grams I start ramping down until about 2.5mL/sec or so. 26-28 seconds from lever pull with about 7-8 seconds before first drip. I tried some pre-infusion in addition on other test runs, but the taste isn't as good. I think a little too acidid leaning toward sour. This seems to be a good batch of La Colombe Nizza. I have a new batch pf Nizza on the way and a few days left of this current batch and also have some Intelligentsia Black Cat from a local roaster also on the way to try.


#10: Post by Phobic »

Vindibona1 wrote:Typically the new arrivals sit in the cabinet for a few days as I finish off the previous batch.
that's not long enough
Vindibona1 wrote:My concern isn't the beans not having degassed, but are experiencing too quick a change while in a de-pressurized vacuum container.
get the basics right 1st then look at the impact of the container, you don't know if it's a degassing thing or a pressure thing because you're doing both at the same time.