Where to buy foil bags and vacuum sealer for hops?

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Aldi had rolls of textured bag plastic on special a few weeks back (along with their own brand vacuum sealer).

If there's a store near you might still find the rolls on sale (I bought some a week after they went on sale).
 
Sorry for bringing up this thread again , but I'm after foil mylar bags for hops. There's lots on ebay but can anyone
recommend a supplier that has a good product at a reasonable price that they have used recently ?
 
Why use foil ones instead of just regular old vacuum seal bags?
It's dark in the freezer anyway...
 
SBOB said:
Why use foil ones instead of just regular old vacuum seal bags?
It's dark in the freezer anyway...
Because almost all plastics are permeable to oxygen or water vapour or both. Vacuum deposition of a microscopically thin layer of metal (aluminium) increases the barrier properties: as an example a typical PET (mylar) fim has an oxygen transmission rate* of 160 mg / m2 / day while the same film when metallised has a transmission rate of 2.2 mg / m2 / day, almost 100 times lower.

That means if you had 100g hops in a bag that was 100mm x 100mm a standard mylar film would admit 3.2 mg O2 / 100g hops / day, while the metallised film would admit 0.044 mg / 100g hops / day.

http://www.slideshare.net/henkywibawa/barrier-properties-of-films-03-12


* Taken with atmospheric conditions on one side and zero O2 on the other.
 
Lyrebird_Cycles said:
Because almost all plastics are permeable to oxygen or water vapour or both. Vacuum deposition of a microscopically thin layer of metal (aluminium) increases the barrier properties: as an example a typical PET (mylar) fim has an oxygen transmission rate* of 160 g / m2 / day while the same film when metallised has a transmission rate of 2.2 g / m2 / day, almost 100 times lower.

http://www.slideshare.net/henkywibawa/barrier-properties-of-films-03-12


* Taken with atmospheric conditions on one side and zero O2 on the other.
Well said
 
Please note that you quoted this before I corrected a mistake: the transmission rates are in milligrams / m2 / day, not grams. I've fixed my post but of course I can't change yours.
 
Lyrebird_Cycles said:
Because almost all plastics are permeable to oxygen or water vapour or both. Vacuum deposition of a microscopically thin layer of metal (aluminium) increases the barrier properties: as an example a typical PET (mylar) fim has an oxygen transmission rate* of 160 mg / m2 / day while the same film when metallised has a transmission rate of 2.2 mg / m2 / day, almost 100 times lower.

That means if you had 100g hops in a bag that was 100mm x 100mm a standard mylar film would admit 3.2 mg O2 / 100g hops / day, while the metallised film would admit 0.044 mg / 100g hops / day.

http://www.slideshare.net/henkywibawa/barrier-properties-of-films-03-12


* Taken with atmospheric conditions on one side and zero O2 on the other.

from a quick google scholar search, doesnt that transmission rate differ with temperature though?

the numbers are less for foil mylar bags, but if you kept your 2 100g hop samples in the freezer for 2 years vacuum sealed in a normal vac seal bag and a foil bag, what would the measurable hop AA%, flavour and usability differences be?
I'm going to go out on a limb and guess 'not much'...
 
Yes it's temperature dependent, as a rough figure transmission rates will about halve in a freezer compared to room temperature.

Re the diff between two foils: from experience packaging foods*, I'd say it's likely to be night and day and will mostly affect the aroma.

It's an easy test to do: put the same hops in a plain film bag and a metallised film bag, keep them a year then open them up.




* I used to work as a process engineer in a big food plant. We paid a lot of attention to barrier properties of packaging films.
 

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