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Nitro Flushing question
mikepetro
OK, I am roasting my own coffee now, and naturally I want to preserve it as fresh as possible for when I consume it.

I am borrowing methods from my old Tea days where I used to nitro flush really sensitive Japanese greens. See http://pu-erh.net...taticID=12

Back then I used foil bags to seal everything. When you are only doing a pound once a year it is no big deal, but manually doing the foil bag thing every 5-8 days would get old and expensive. So I decided to use Canning Jars and my Foodsaver to vacuum them.

I am filling up 8oz jars with roasted beans (about 2 days? worth), sticking my nitro nozzle down into the beans till I hit the bottom of the jar and then flushing it real good. I feel plenty of gas flushing through the beans and out the top of the jar. I then move the flat lid over the jar opening as I pull the nozzle out. I know I am not getting a ?perfect? flush but I figure I am getting 95% or better of the oxygen out of the jar. Its quick, easy, and I already have the nitro tank.

Here is my question:

Is it better to let the beans degas overnight and then pull the vacuum, or to pull a vacuum on the jar right away?

I figure that if I have flushed the O2 out of the jar and put just the flat lid on without the band, then the degassing will create a positive pressure in the jar and gas will escape but none will enter, so theoretically no O2 gets back into the jar. Then pulling the vacuum the next day leaves me with a nice vacuum sealed jar until I use it. I can feel the vacuum break when I open the jar.

When I use the other method, i.e. if I flush and then pull a vacuum right away I get a nice vacuum for a few hours, minimal O2, but as the CO2 degases it builds up pressure in the jar. I can see the lid bulge slightly the next day and I feel the jar ?pop? from the pressure when I open it.

Is either method superior to the other, for example if I want to store them for 2 weeks? Does more CO2 in the gas mixture affect the beans? Does being held under a slight pressure alter the beans somehow?

BTW, I am using the same method for storing my green beans. Pack them 227g to a jar (single roast) then nitro flushing them and vacuuming them, the degassing pressure is not an issue there though. From what I have been reading, nitro flushing and/or vacuum packing seem to be preferred methods of storing quality greens now.

Would love input please?..
Mike Petro
Martinsville, VA
--------------------------------
Lady Silvia, Stepless Rocky, Gene Cafe
http://mikepetro.org/coffee/
JETROASTER
Nitro-flush for coffee never made sense to me.
That doesn't mean that it makes no sense. It only means I don't understand.

Fresh coffee into a container, with a one way valve. The coffee is essentially 'self-purging' the container as it degasses. No need for nitro.

To allow the coffee to degass completely before sealing sounds like preserving stale coffee.

So, I just stick with the one-way valve method.

My 2 centavos. -Scott
mikepetro
Hi Scott,

My logic is that even with a one-way valve you are starting out with 20% oxygen that fills all the void space in the container. The less full your container the more void space you have filled with air, hence the benefit of a vacuum when using bags. . As the coffee degases it will mix CO2 with that 20% O2 thus diluting the concentration, but the O2 doesn't get replaced, it is still there until enough pressure builds to overcome the valve. Once it overcomes the 1-way valve the resulting pressure from degassing will expel a mixture of O2 and Co2, thus removing some of the O2. but there is still O2 left in the container, it never gets completely removed, it just keeps getting diluted until the degassing stops.

By flushing the container with nitrogen, before sealing the container, you "displace" the atmospheric O2 with pure nitrogen, thus actually removing the O2. Then as the coffee degases you are mixing CO2 with N2 (both inert) as the O2 has already been taken out of the equation.

Since it is O2 that oxidizes the oils, making them less aromatic and eventually rancid, it would seem that every molecule of O2 that you can remove the better the preservation. So even with a 1-way valve I still see the benefit of nitro flushing if you are shooting for maximum preservation.

At least, that is my understanding of it, I could well be misunderstanding something........

And I wonder, how much difference does it all really make unless you are shooting for a shelf life of a month or more.
Mike Petro
Martinsville, VA
--------------------------------
Lady Silvia, Stepless Rocky, Gene Cafe
http://mikepetro.org/coffee/
JETROASTER
"And I wonder, how much difference does it all really make unless you are shooting for a shelf life of a month or more."
--------------------------------------------------------------------------------
Yeah , I think that's it. Purging every bit of O2 is obviously more thorough.....but does it show up in the cup after 1-2 weeks?
Well, not to me, but my tastebuds are not nearly as good as some others. -Scott

jedovaty
You wrote that you are using a foodsaver on the jars. Why does the nitrogen even matter then? Are you assuming the foodsaver does not suck all the O2 out, therefore you are using the nitrogen to eliminate as much as possible? It seems over the top to me, but then, a lot of the fun in this does involve going to the extremes, and I've been there myself in other hobbies.

It might be a fun experiment to try and see if you can taste a difference, long term and blind?

Anecdote, not to take this off topic, just for your laughs: I tried a short experiment over a month's time with commercial roast from local roaster, before I started roasting my own:
- vacuum sealed a jar and put it in the freezer
- vacuum sealed a jar and left it in the cupboard
- put beans into a ceramic, airtight container

A month later, I couldn't tell the different between the two vacuumed jars, but was able to pick the ceramic out each time, and learned I preferred the taste from it. But that's me :)

mikepetro

Quote

It seems over the top to me, but then, a lot of the fun in this does involve going to the extremes, and I've been there myself in other hobbies.


Ahhh the pursuit of perfection obsession, yes I know it well, and am indeed up to my neck in it with this coffee thing. You should see what I did to my espresso machine......

Quote

but does it show up in the cup after 1-2 weeks?

Quote

It might be a fun experiment to try and see if you can taste a difference, long term and blind?


This is indeed something I aim to try.
1) With nitro - immediate vacuum
2) With nitro 12 hr delayed vacuum
3) Without nitro 12 hr delayed vacuum.

Same roast, wait 4 weeks, weigh and brew identically using a pour over, then let my SO mix up the cups. Should be interesting!

I will do a similar test on green beans, though my skill at duplicating roasts is not quite there yet (at all). One batch in a vacuum jar, one batch in a nitro jar, wait 6 months and roast. I suspect the view might actually be worth the climb for nitro on this one.

Anyway, its fun playing with the variables.. I wouldn't suggest going out and buying the nitro stuff, but I already had it so I figured I might as well explore it.

Now if I could just figure out how to roast this Indonesia Organic Flores Wet Hull Bajawa. Haven't tasted it yet my first roast last night came out rather uneven and visually unappealing.
Mike Petro
Martinsville, VA
--------------------------------
Lady Silvia, Stepless Rocky, Gene Cafe
http://mikepetro.org/coffee/
jedovaty
Blind tasting is usually the way to go, and has always been an eye opener for me. When I started with coffee, I spent a few months agonizing over grinding immediately before brewing. The gf got tired of it, so we decided to do a blind test with a number of variables spread out over a few days. Turns out though we could tell difference, there was neither consistency in the results, nor a preference. So, we ended up taking the path of least resistance, and enjoy drinking.

Not to say the science behind it all was fun :) I actually do enjoy occasionally pursuing the silver bullet.

Sorry to go off topic here. Good luck with the nitrogen project. Too bad there isn't a way to speed up the testing, what are you going to do in the six months waiting?!
JETROASTER
Mike, Thanks for sharing the nitro experiment. Would you willing to freeze a sample as well? -Scott
jkoll42
Besides being an interesting experiment, what would the benefit be of nitro v freezing? Freezing is an established safe way to preserve, easy and free.

For me I would be more interested in a 1 week and 2 week cupping. See if an inert environment would change the taste vs a partially oxidizing environment. Better, worse, dunno!?!
-Jon
Honey badger 1k, Bunn LPG-2E, Technivorm, Cimbali Max Hybrid, Vibiemme Double Domo V3
JETROASTER

Quote

jkoll42 wrote:
Besides being an interesting experiment, what would the benefit be of nitro v freezing?


Nothing beyond rolling the dice. You never know! -Scott
mk1
Mike,
I'll throw in my 2 cents. I obsess over oxygenation in beer racking and storage and also my frozen hop locker and green bean storage and roasted coffee and too many other things .
One thing I came across was a statement by Dr. Charlie Banforth ( famous in the beer world, teaches at UC Davis). He states that oxygenation reactions in hop and beer storage are far more temperature dependent in aging as compared to the level of O2 in the container. I think he said oxygenation reactions occur 10% faster for every 5 degrees higher in temp, (or was 5 to 10 the other way)? I could look it up. Anyway the gist of his findings were that it is far more effective to lower the temp than to remove the oxygen for hop storage in particular (around 10F or less is very effective). I know there are other issues involved with green and roasted coffee storage. I always let my fresh roasted coffee sit open until it really smells like coffee before vacuum sealing in the mason jar.

Roast Strong!
Mark
Edited by mk1 on 03/15/2012 10:32 PM
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