I have coffee I bought a year ago from Coffee Snobs in Australia. I recently noticed the flavour had rapidly diminished since when I first bought it. I thought: Is there a better way than storing it in burlap/cotton bags in my kitchen?
Short answer: Yes. There’s a better way.
What to control for
- Keep humidity between 50-70%. Coffee responds dramatically to small changes in humidity. On average, coffee leaves the mill with a 12% moisture content; it should be roasted at that level. Coffee that has absorbed moisture even just up to 13% can be ‘bleached out’ and have muted flavour (as I experienced). There’s no agreed ‘perfect’ level of humidity, though various sources (blogs, suppliers) agree a range of 50-70% humidity would be appropriate.
- Keep temperature between 5 and 20 degrees C (40 - 70 F). Temperature level is important, as is stability. So is ventilation and insulation (to avoid temperature shocks). Freezing is not a solution - some storage experts say if coffee freezes it has a dehydrating effect and results in a less intense cup with less edge! Experts (blogs, suppliers) generally arrive at a range of 5-20 degrees centigrade (40-70 fahrenheit) as an acceptable range to keep the coffee - preferably towards the cooler end.
- Segregate coffee from foreign odours. Keep coffee in a clean environment. Don’t put it around other odour-producing items, including foods or chemicals. This would mean, usually, its own container, drawer or cupboard.
What to do
I’ll boil this down in three levels - 1. Easy and acceptable, 2. Better but harder, and 3. Best and hardest. For all these methods, you must keep the coffee in a moderately cool, humidity controlled environment such as a cupboard in a room in which most people would be comfortable.
- Easy and acceptable: Store your coffee in burlap or cotton bags in their own cupboard space. It’ll be good this way for up to three months, assuming the environment is controlled.
- Better but harder: Use multi-laminate grain storage bags (like GrainPro). These are a grain storage bag that has gained popularity in the coffee world, and are basically a giant sandwich bag with zip lock, but built with multiple layers and a vapour barrier between them. It has been reported (by Sweet Marias, citing an article in Roast Magazine) that storing coffee in GrainPro bags can increase shelf life by up to 3-6 months. Conservatively, this means you can store this way for up to six months, again assuming climate control.
- Best and hardest: Use vacuum packing. This is time consuming on a large scale, but easy to do for a home hobbyist. Buy some vacuum packing bags, store coffee in them, and seal them with your vacuum cleaner. If you do this and use multi-laminate bags and have climate control, you can store for up to 9 months.
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