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lukeHeuer · 2019-03-15 · Original thread
Sure, coffee roaster here. It's false that allowing beans to degas c02 preserves them indefinitely as the parent comment seems to imply. There is however about a 10-hour window after roasting where degassing of c02 is so vigorous it impedes oxidation. Freezing vacuum sealed coffee, both green and roasted beans, will preserve it almost perfectly for years because freezing decreases oxidation rates by more than 90% and slows the movement of volatiles.[0] Enough people have documented and tested this and it's very common for Cup of Excellence winning and other notable coffees to be stored for extended periods of time this way. There are even cafes with reserves of such coffee, you can walk in and they'll pull winners from years ago for you to try. Scott Rao documents the research and resulting evidence of why it's beneficial to freeze coffee in his book The Coffee Roaster's Companion.[1] It's just not economical at scale, or necessary. Green coffee is "fresh" for about 9 months on average, most roasters go through specific lots of coffee well before that window closes. The sad reality is that most roasted coffee is well past its peak by the time it reaches the consumer.

You can conduct an at-home experiment yourself by finding a local roaster, asking when their roast days are and if you can get some coffee from that batch before it's allowed to rest. Seal and freeze a portion while keeping the rest in a normal valve-release bag and compare after a week or two.

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