Experimenting with this technique
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This is really a development of my ideas in the article One Way Valves and Coffee Storage. My objective here is not to necessarily lengthen the time the coffee can be stored, but to maintain it for longer at that peak of flavour we know usually seems to last only a few days. This means we can enjoy the coffee at it's very best. It also may affect the quality of the flavour in other ways….possibly better, possibly worse. I also want to stress that this is not in any way a commercial packing process, where they flush (usually) already stale coffee with Nitrogen. This is intended to describe a simple and hopefully effective process, that is within reach of the home consumer.
It all started when I was watching TV one night about 6 months ago and when idly flipping through the channels I chanced upon one of the well known shopping channels. I saw this product and have waited for it to reduce in price (which it hasn't done).
http://www.householdinnovations.co.uk/shop/packmate-vacuseal-vacuum-food-storage-p-336.html
Now this particular unit is a bit special in that the bags are washable, reusable and resealable via a zip closure system. I have never really stopped thinking about this device, as I firmly believe Oxygen is responsible for significant taste damage in all foods.
Now the chemist in says, that whatever we do, unless we eliminate the Oxygen that's already there, then we will get some staling. It doesn't matter what gasses are formed during the days after roasting, they cannot really prevent oxidation, whilst the original amount of oxygen was present, sure by dilution they can reduce it (if you have a one way valve), but that's all. It could of course be that coffee tastes better after 3 days, is that a certain amount of oxidation is required?…But perhaps not!
Now don't confuse Vacuum storage with storing the coffee under reduced pressure, that's exactly what I DONT want to do, what I do want to do is eliminate as much oxygen as possible, so a pliable plastic bag is ideal (not a rigid container).
If you think about it, we never manage to get coffee that has not oxidised, unless we drink it straight after roasting it, but of course it doesn't usually taste good. This also isn't so much about extending the shelf life of roasted coffee (which it will do of course), but about having 3-5 day rested coffee that has minimal oxidation.
- What will it taste like, will it be better
- Is Oxidation required to "mature" and develop flavours in the coffee
- Can we rest for longer and get better flavours
- How well will it store for
- If we remove air from the bags each time we take coffee out, what effect will it have
Well I have invested a whopping £29.99 in the vacu seal system and some extra bags. At the moment i have simply roasted up 250g of Guatemala Finca Isabel and sealed it up. I want to first develop the techniques, ensure that I overcome any of the potential problems:
- Do the bags and vacuum system work well
- When the coffee degasses and vacuum starts to weaken, will the one way valve allow oxygen in?
- Is it worth trying to seal the valve with some tape.
Answers so far.
1. yes, very well, I have a solid brick of coffee in the cupboard
2. I noticed in some testing that the vacuum sucks the valve in and it must be a sort of "push" fit, as when I released the vacuum by breaking the seal open, when I sucked on the valve, there was a definite resistance and "pop" as the valve opened…..that's a good sign.
3. It would be very difficult to do, as on closer examination, I found the valve body swivels, so there may be the potential for some air to possibly leak in.
To do this properly, I need to roast the same coffee the same way and roast a number of batches and simultaneously pack them, treating them each in different ways. e.g.
In the above image the blue arrow points to the base of the valve, where the smaller piece actually swivels against the larger piece. So although there is a tyre valve cap on there, if air was wanting to get in, it possibly could at the point where the valve assembly swivels. However, because I think the valve has a small positive force keeping it close, or it's "pushed" into place by the vacuum, I don't think air will bleed back in even when the degassing increases the pressure within the bag. If it becomes a problem, my final answer to solve it would simply be a large blob of Blu-Tack.
Rest Coffee for 3 days
pack, vacuum seal, and leave to rest.
Pack, vacuum seal, and re vacuum each day whilst resting.
A control packed normally in the home made 1 way valve jars
Rest coffee for 14 days
pack, vacuum seal, and leave to rest.
Pack, vacuum seal, and re vacuum each day whilst resting.
A control packed normally in the home made 1 way valve jars
Now the only reason here for doing 14 days, is that it will emphasise flavour changes and degradation and make them easier to detect
But for now the initial rough testing phase, just to get familiar with the system.
Day 1
Solid brick of vacuumed Guatemala Finca Isabel (Medium to medium dark Roasted), packed within 10 minutes of roasting.
Day 2
The vacuum packed bag is now noticeably softer, sure gas has been released, but has not inflated the bag as much as I would have guessed. As I know that there is a reasonable amount of gas produced, i think this shows just how much air (Oxygen) I managed to remove from the bag. resisting the temptation to re-vacuum it, but for this test, I want to just leave everything to happen naturally. When I repeat the test, I will re-vacuum the bag each time.
Overall though, as the coffee degasses, I think it unlikely that any significant amount of oxygen will flow in through the one way valve. I was pleasantly surprised with just how much air the system gets out, i would think there is very little Oxygen in there now.
I am of two minds though, whether to keep sucking out the CO2 as the coffee degasses, or leave it. Possibly i should test both methods. certainly when i am using the coffee, I will actually re-vacuum seal the bag after I take coffee from it to drink.
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