People often ask me the quickest way to improve their home coffee. The first three things I inquire about are their grinder, the quality of coffee they buy, and the freshness of their coffee. This inevitably leads to them asking me the acceptable parameters for coffee freshness. Here are my six quick rules:
- If I don’t know the roast date, I don’t buy the coffee. Best before dates don’t count, except they usually indicate a roaster that chooses to ignore the importance of freshness.
- For espresso, I usually find the beans need at least 3 days of aging, usually 5 depending on the method of storage and the bean.
- For coffee that I’m going to use for espresso that is packed in brown paper bags, I don’t buy anything older than 5 days.
- For coffee that I’m going to use for espresso that is packed in vacuum sealed packs, I don’t buy anything older than 7 days. If it is also nitrogen flushed, I extend to 9 days.
- For coffee that I’m going to brew using other brew methods, I will usually move the cutoffs 2 days earlier, although trends are now suggesting longer resting times as well.
- I don’t buy more than I plan to consume in a week, maximum 10 days.
Why these tough guidelines? I’m looking to achieve great shots as often as possible. I’m not looking for average or good. I have a fancy machine and grinder, so why should I settle for average.
Most people would buy 3 day old Wonder bread, but most people would not buy day old specialty bread in a bakery? So why do some people buy 2 week old coffee? I chalk it up to the nature of roasted coffee and experience.
Nature of Coffee Aging
With specialty bread it is very easy to figure out the difference between fresh and old bread. The biggest factor is texture. For starters, fresh bread is soft and easy to chew, while old bread is hard and difficult to chew. When buying bread, consumers often give the bread a squeeze.
Compare this to coffee. The changes in roasted are much more subtle and slow in taking place. Generally for espresso, I find that I enjoy it in the 4 to 14 day range after roast quite a lot, with my best shots usually in the 7 to 10 day range. For other brew methods, I usually find the 2 to 10 day range the best. After roasting, coffees usually gain in taste during a period of degassing and aging, but after a period of 2 to 7 days, the coffee begins to deteriorate. Slowly at first, but after some time it will lose flavor becoming bland, then sour with more dirty notes showing up. These changes are subtle to detect and require taste memory when you are not tasting side by side, but I encourage all readers to save a couple of shots from a previous bag and compare with a new bag. You will definitely notice a difference.
Packaging – How Roasters Prolong Freshness
Roasted coffee’s biggest culprit for causing staleness and degradation is oxygen. For roasters who have decided to try to extend their coffee’s life, packing in one way bags with one way valves is usually the first option. The better option is to vacuum pack which greatly reduces oxygen in the bag. As coffee rests and degasses, it will give off carbon dioxide. In these sealed bags, the valves let excess gas out when under pressure. This leaves less oxygen in the bag. I have read about studies that have shown that oxygen content is about 10% in bags that are not vacuum packed, while in the 2 to 3% range from those that are vacuum packed.
Some roasters have taken this a step further and additionally nitrogen flushed the bag before sealing. This further reduces the oxygen content to levels around 1 to 2%. With its inert properties, nitrogen slows the staling process, while still allowing some aging to take place. In large, reported taste tests have confirmed this, and my general tasting impressions agree. Other reports have indicated that when the bag is open that degradation happens at a faster rate. I have not been convinced either way, although this is important for home baristas who tend to take up to a week to go through a bag.
Consumers – Methods of Preserving Freshness
Although roasters often take measures to preserve coffee, consumers have long tried different methods to extend life. The simplest and most obvious is to keep the coffee well sealed away from air in a dark bag by squeezing out air from the bag, and only filling up the hopper as needed. More effective methods of eliminating air include containers with vacuum pumps such as Airscapes.
Finally, a method that is often discussed in forums, is freezing coffee in separated small batches that can be pulled out every 4 to 7 days as needed. Although freezing has risks and possible negative effects on coffee, many professionals and serious amateurs whose opinions I trust have described methods they use with success. I have not had first hand experience, but encourage people to experiment with techniques they may read about. Of course, side-by-side blind tasting is always the most sure way to come to conclusions.
Although this information and tips are old news for many coffee nuts, I thought it might be a useful summarization for those wondering about the importance of freshness. I encourage everyone to demand it from their roaster or whoever they may but coffee from.
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