The study that gets 'quoted' by PBi is found here:
http://www.pacificbag.com/articles/VALVEEFFECTIVENESSSTUDY.pdfThe observations that I would note are that:
A) they do not reveal anything about "Competitor A"'s ID other than that they supply small and medium-sized roasters with valved coffee bags - this could be anyone...
B) they do not describe which types of bag materials are examined or whether they were truly equivalent
C) they do not tell you if all of these samples (theirs and the competitors) were mixed together and analyzed blindly by the independent lab - and it appears that they are from different analysis groups...
and
D) they do not give quantitative time frames for how long the bags were on the shelf, or how they were treated in the interim.
SYNOPSIS:A) In 2005 and 2006 (when they did the study), there were quite a few valves available from Chinese and Korean knock-off vendors, and I know we discussed this out here. Some of these were notorious for leaking, and I remember there was even some trouble at the time with some vendors having bags with valves from several different sources at once. The Pack Plus Converting valves fared
much better in my own testing than the ones without a manufacturer stamped on them. Anyway, I would bet that the comparison is being made to one of the 'no-name' valves, not Pack Plus. In fact, in the article PBi admits:
Our studies show there are numerous established and functioning, or ?true,? one-way degassing valves on the market including those manufactured by Pacific Bag, Inc. Unfortunately, our studies also show that there are other products, touted as ?one-way? degassing valves which consistently allow significant amounts of oxygen to penetrate packages. As an example, we conducted various tests on degassing valves supplied by a competitor known for supplying coffee packs, plus valves to smaller and medium-size coffee roasters (named Competitor A for this study).
(Bolding by BW) I think I still have sample bags at home from PBi, with their stickers on them, and Pack Plus embossed valves.
B) There are lots of different kinds of bag materials (there are good descriptions of permeability at SorbentSystems.com). If you have a clear side to the bag, or a window, you do not have a foil layer, and you get O2 and H2O permeability that is at least an order of magnitude greater than a foiled mylar (which is actually made up of several different layers). There are also several thicknesses of foiled mylar available. The competitors bags
could have been of different thicknesses and construction in the PBi study, they do not give you this information. Usually when a bag fails (in my experience), it is due to a poor heat seal or poorly attached valve, although there certainly are a good share of non-functioning valves...
C) It appears that the samples compared in this study were analyzed at two different times, which could indicate 'cherry-picking', or using the most favorable data to make the comparison. They
may have done each group (theirs and competitors) at the independent laboratory multiple times, the report does not give enough information to determine...
D) Were the competitors bags shipped around a lot? Roughly handled by store stockers? Left in hot trailers? Frozen? Were their own bags subjected to the same handling? How long had it been since each bag was sealed? How did the O2 level compared to the time (since sealing) compare to the material specs for permeability?
