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Topic: nitrogen flush (16 msgs / 305 lines)
1) From: Kevin DuPre
My selected roastery for my planned business has a
heat sealer with a two step cycle - vacuum pull
followed by nitrogen flush into a valvebag which is
then heat sealed. There are no O2 left behind after
this. Lavazza also uses this for the coffees they ship
worldwide. They claim 2 years. 
However, even a small heatsealer with vacuum/nitrogen
apparatus is very expensive - for a unit that will do
both 1/2,1, and 5 lb bags you're talking $8000-10,000
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=====
--
Kevin DuPre
obxwindsurfhttp://www.virtualfusion.com"The real voyage of discovery consists not in seeking new landscapes but in having new eyes -- Marcel Proust"
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2) From: Dan Bollinger
<Snip>
Do you know for a fact that Lavazza uses vacuum?
Why two step?   You are vacuuming only to destroy the vacuum with nitrogen
filling.  Considering the low cost of nitrogen you could accomplish the same
thing with a nitrogen fill alone and spare yourself the expense of a vacuum
chamber. It could go like this:  fill the pleated coffee bag with beans,
insert a small metal tube near the bottom of the bag, slowly inject enough
nitrogen to more than fill the bag and seal immediately keeping the bag
vertical at all times.  Between the flow of nitrogen from the bottom up and
the fact that nitrogen is heavier than air, I think you'll end up with about
the same amount of O2 than with vacuum processing with much less expense and
maintenance. hope this helps, Dan
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3) From: AlChemist John
Sometime around 05:18 8/14/02, Dan Bollinger typed:
<Snip>
I have a feeling that this is one of those items that in theory should 
work, but in practise does not.  Even with N2 being heavier than air, 
regardless of how slow you introduce it, there would be considerable 
mixing.  The density difference is VERY subtle.  That would be the reason 
for the two step.  Remove the O2, then refill with N2.
Not that I really think it is necessary, but there is also the option of 
looking into something to scavenge of O2. Something akin to the moisture 
control  descant packets found in so many packaged foods.  Maybe a small 
packet of  vitamin C.  It is an anti-oxidant, but I wonder what it could to 
the coffee.
--
John Nanci 
AlChemist at large
Roasting and Blending by Gestalt
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4) From: Mike McGinness
From: "AlChemist John" 
 Not that I really think it is necessary, but there is also the option
of
<Snip>
to
<Snip>
Seehttp://www.sorbentsystems.com/o2absorbers.html.They sell oxygen
absorber packets designed for vacuum food preservation. Packets of powdered
iron oxide. They claim to bring total oxygen level down to .01% or less with
vac & sealing. I haven't tried them yet but may after this discussion
string...
MM;-)
Home Ju-Ju Variable Variac Rockin' Rosto Roasting in Vancouver, WA USA
Grindin' & Brewin' with Solis Maestro & Miss Silvia
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5) From: Dan Bollinger
<Snip>
Theory?  Like I said, it is used in practice for over twenty years by
companies doing the same thing you want to do, preserve food.  The heavier
than air aspect means that once the bag is full of only beans and nitrogen
O2 won't seep back in before you have a chance to seal the bag. Of course if
you tilt the bag the nitrogen will 'pour' out.   Why this preservation
process works without vacuum is because you are using many more times the
nitrogen than it takes to fill the bag.  All the air is being flushed out by
the flow of nitrogen.  I use nitrogen injection to scavenge air for
chemicals that are moisture sensitive.  I insert the tube, press the valve
on the can and count to ten.  It works, ain't no theory about it!  And, you
don't need a vacuum pump nor vacuum chamber. :)   Dan
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6) From: EskWIRED
<Snip>
Survivalists pack grains for long-term storage in 5 gallon buckets.  They
flush with nitrogen, and put in oxygen removers, which are basically small
packs of iron filings.  The iron mixes readily with the oxygen, getting rid
of it.
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7) From: EskWIRED
<Snip>
 I use nitrogen injection to scavenge air for
<Snip>
Where do you get cans of nitrogen?
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8) From: Dan Bollinger
I get them from the plastic supplier when I buy the urethane resins I use
for work.  I'm sure there are other sources for them.  They are expensive,
but then so is the resin it saves. If you intend to use a lot or air, like
for a business, go to an industrial welding supply house.  Dan

9) From: Dan Bollinger
<Snip>
rid
<Snip>
When I've packed emergency food in 5-gallon pails I purge with nitrogen and
then drop in Mortons salt.  Salt is a dessicant, removing moisture which
comes off the foodstuff.  Besides, you'll be wanting the salt, too.  Dan
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10) From: William Hoffman
Good Day All,
I believe I was told that welding supply house nitrogen was not food
grade or pure.  Is this incorrect?
Is there such a product as medical grade nitrogen?
--
Kind Regards,
William of Orange Park, FL

11) From: William Hoffman
Good Day All,
I believe I was told that welding supply house nitrogen was not food
grade or pure.  Is this incorrect?
Is there such a product as medical grade nitrogen?
--
Kind Regards,
William of Orange Park, FL
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12) From: Rick Farris
Mike wrote:
<Snip>
I'd be interested in going in on a case of the 25cc packets...
-- Rick
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13) From: AlChemist John
Sometime around 06:42 8/14/02, Dan Bollinger typed:
<Snip>
I must have missed that comment.  It sounded like you were theorizing, not 
speaking from experience.  Sorry about that.
--
John Nanci 
AlChemist at large
Roasting and Blending by Gestalt
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14) From: Ryuji Suzuki -- JF7WEX
From: AlChemist John 
Subject: +Re: nitrogen flush
Date: Wed, 14 Aug 2002 06:20:03 -0700
<Snip>
Vitamin C's reducing (or antioxidating) action is strongest in
alkaline solution. In dry acid form the reaction is very slow and
practically useless. (remember our blood has pH a bit above 7,
maintained by bicarbonate buffer.)  This is the same for erythorbic
acid or D-ascorbic acid, isomer of L-ascorbic acid. There are some
oxygen absorber that work well in dry form, but all these things work
to a limited extent that vacuum sealing and good gas barrier material
(like foiled mylar) must be used simultaneously.
After all, this discussion is going way too much compared to what's
necessary to preserve roasted coffee for a few days... or why do we
home roast?
--
Ryuji Suzuki
"I can't believe I'm here.
People always say that I'm a long way from normal."
(Bob Dylan, Normal, Illinois, 13 February 1999)
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15) From: Ryuji Suzuki -- JF7WEX
From: "Rick Farris" 
Subject: +RE: nitrogen flush
Date: Wed, 14 Aug 2002 14:14:51 -0700
<Snip>
Do they come in individually sealed form? If no, are you going to use
the entire case as soon as you open it?
I have not seen any evidence that oxygen is the only factor affecting
staling of coffee. If there are other factors leading to hydrolysis or
self decomposition of some substance in the coffee bean in absence of
oxygen, all these efforts may be practically useless.
--
Ryuji Suzuki
"I can't believe I'm here.
People always say that I'm a long way from normal."
(Bob Dylan, Normal, Illinois, 13 February 1999)
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16) From: Rick Farris
Ryuji wrote:
[about oxygen absorbers]
<Snip>
According to the link (start here:http://www.sorbentsystems.com/o2absorbers.html)as long as you get them
sealed up again (in a vacuum) within 20 minutes, or so, you're alright.  My
personal strategy would be to immediately repackage them in packages of 6 or
10, for use when I roast.
<Snip>
One must start someplace.
-- Rick
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