Those one way valve bags...

[Alun_evans]

Generally the valves are pretty good- if they are the quality Swiss or US valves. However those made in the PRC have quite a high failure rate. A friend roasting locally uses the PRC ones and has a failure rate of 2.5%- which is incredibly high IMHO.

 

[Pangib]

I've been thinking a lot about handling the coffee post-roast lately. The best I can really do is make observations based on intuition and common sense. I haven't really (yet) done any extensive testing that gives any of my decisions validity.
What I do know: coffee is a food product and enters a state of decomposition as soon as the roast is finished.

Beans begin to give off cO2 after being roasted. They give off less and less as time passes. (first few days)Does the cO2 affect the flavor of the beans? I'm assuming it does and if so should it be removed? How is this usually done? With some sort of vacuum? Where can I get one?
Also, I've heard of roasters that leave the beans in the bag, with the bag open for a period of time to allow the majority of the cO2 to leave the beans without being confined to the bag, the thinking being that the cO2 gives the beans a "gassy" taste. I'm assuming this is different according to origin, but generally, how true is it that the cO2 transfers a gassy taste to the beans when the bag is closed immediately after the roast?

Oxygen, moisture, and heat are the enemy and everything should be done to protect the beans from it to ensure freshness. To ensure O2 is kept away I understand that many roasters use nitrogen to "flush" any oxygen between the beans out before the one-way valve bag is sealed.
What affect does nitrogen have on the flavor of the beans, if any?

In my experience freshly roasted coffee should be used within the first 12-15 days. However I've heard it argued that if the beans are nitrogen flushed and stored in bags with one-way valves they are still good after 30 days. The reasoning behind this being that because there is no oxygen getting in at all the shelf life is prolonged. I'm not sure about this, surely the issue is decomposition/oxidation that will happen regardless of environment, not actually or primarily exposure to oxygen.
Won't the beans will eventually begin to stale regardless of all protective measures being taken, because decomposition/oxidation is an inevitable, natural process. And, is the "standard" period of freshness 12-15 days or 30?

I'd love to hear some thoughts on this.

 

[Alun_evans]

Hey Pangi, I am currently struck down with the lurgi- not really feeling anywhere near 100%- but as you also messaged me on the other forum. In my opinion we as roasters have to try and make the best choice for our roasted product- and work also within commercial (ie : we have to make money) parameters. I am nt one of those who commented that my product will sell itself super quick- hence Kraft Paper is an option. Our product goes all over Indonesia- infact it travels to some pretty far corners. To that end we need not only a bag that will act as a barrier against external influences, but also have durablity. You will know from your research that teh NZ Coffee Roasters Assoc has a "10 day" freshness window for coffee. Now we are also roasting in Auckland, that is fine- roasting smaller volumes, more often. In Indonesia we do follow a similar rule for our own cafes- but it is impossible to put such a limited expiration time frame on product being shipped 000,s of miles on dodgy planes, boats and automobiles.

OK, it is generally recognised that C02 is not the perfect environment for coffee- however it beats Oxyidisation hands down. Although CO2 is in parts O2 of course. Most large roasters have worked out vacum packing is not the best way to go either- it requires, in part, staling of coffee during the packing process. Packing using Nitrogen flushing probably is the best way to preserve quality in the packet... of course in saying ALL of that- indeed the NZCA is right- fresh IS best no matter how you pack.

On the ther forum there was a great deal of debate about using biodegradeble packing. Waxed Kraft paper is similar to the waxed paper cups many of us use- in a landfill, and mulched it can still take 3 months to begin breaking down- vs using ALU packing which does not breakdown but can (and is) recycled. For me a decend ziplocked plastic pouch with a decent swiss 1 way valve is still about the best option for anyone from a small home roaster to a roaster producing several ton a week.

 

[PinkRose]

Hi Alun,

What is lurgi?

Whatever it is....I hope you'll be feeling better soon.

On another note....it's amazing how many people don't know what the one way valves do. It would be great if there would be a little blurb on the packaging to explain what the valve does. For example, there is a elderly gentlemen who sometimes helps out in the cafe where I work. One morning he decided to open up a carton of 5 lb. bags of roasted coffee beans that was just delivered. The bags have one way valves, but apparently a couple of them were unusually puffy. Since the guy didn't know any better, he took a tiny pin and punctured the bags to "let the air out" so he could get them to fit better on the shelf.

Needless to say, the manager was very upset when she walked in and saw what he was doing. She realized that he thought he was helping.......and so he was told to just mop the floors and wipe down the display cases from now on.

Live and learn!

Rose

 

[Alun_evans]

Hey Rose, feeling a wee bit better...not 100% but Ok. Nice story about the valves, I can for sure believe it!