One important thing to consider is your definition of 'vacuum-sealed'

I occasionally 'vacuum-seal' beans at home using a food-saver. The foodsaver is just a pump that sucks air out of the bag and then seal it. The beans are not 'under-vacuum' meaning without atmospheric pressure.

However, using a chamber-vacuum machine (like we use in professional kitchens) the beans would (during the vacuum process, not once the bag is sealed) be in a vacuum at less than atmospheric pressure. These machines are capable of boiling liquids at room temperature, I don't think it's a stretch to imagine them screwing up coffee beans.

For home users with simple edge-sealing vacuum sealers, I don't think there's much to worry about.

This! I vac seal, using the typical strip sealer, my beans in glass jars and then into the deep freezer with neglible if any detriment to their flavor potential (like most frozen stored food, it's time relative..."nothing gets better in the freezer" ).

spressomon wrote:..."nothing gets better in the freezer" ).

You haven't met my mother-in-law!
THANK YOU! You've been a great audience!

I need a new signature.

hamish5178 wrote:However, using a chamber-vacuum machine (like we use in professional kitchens) the beans would (during the vacuum process, not once the bag is sealed) be in a vacuum at less than atmospheric pressure. These machines are capable of boiling liquids at room temperature, I don't think it's a stretch to imagine them screwing up coffee beans.

I'll let you know in a few weeks. I just got a chamber-vacuum machine today and used it to package and freeze several different varieties of beans. I tried it with bags and small mason jars.

Several years ago there was a long running discussion regarding freezer storage of coffee, green and roasted with or without vacuum on the Sweet Maria's e-mail list. Thee was discussion of N2 flushing as well. The list archives are open to all. Those Seal-A-Meal machines pull a very good vacuum, not quite diffusion pump grade but as good as any mechanical vacuum pump.

Back to the original question though. Repeated vacuuming of the same container of beans as you withdraw enough coffee for a single dose does not sound like the best process and probably on balance harmful. Cold storage, either N2 purged or vacuumed, should provide the longest storage life.

My issue is, I don't use more than around 35 grams of beans per day. I buy single origin stuff from various roasters and find that the majority of it suffers a noticeable amount of degradation in the span of only a couple of days once the bag is opened.

Really hoping this small-jar inert-gas-storage thing pans out. Otherwise I guess I'll look into freezing.

How was on the balance harmful detemined?
My personal testing at home finds it very useful.

Frozen and evacuated or inert gas flush for longterm storage. Once moved to refrigerator section then inert gas flushing or just an air tight container should be adequate. Repeated opening and evacuating the refrigerated storage container will introduce a fresh dose of O2 into the beans at every opening. If the air tight container is used without any vacuuming then the bean interior and the exterior environment will be at the same or effectively the same pressure and you will not be using atmospheric pressure to force O2 into the beans at every opening. Now if you flush the air tight container with an inert heavier than air gas this would be the best solution for refrigerated storage to supply daily consumption.

I'd skip the refrigerator storage all together. Deep freeze for storage & a sealed container (jar) with enough for a couple days on the coffee bar.