There is a very interesting conversation going on at www.baristaexchange.com
"How long does coffee stay fresh in the doser?" but I have changed the question to: "How long does coffee stay fresh after being ground?"
Well, the answer seems to differ according to the source such as a smaller, speciality coffee roaster or one of the commercial brand names that roast in machines which are a big as a living room...
Most of the larger roasters claim that roasted coffee can be kept fresh for up to one year if properly handled after roasting (and grinding) and then packing the coffee in double laminated one way valve bags and in the case of filter or ground coffee, the coffee would have to be vacuum sealed.
Well, to be honest... I have personally found that coffee beans do stay reasonably fresh if it is kept as properly stored with as little interaction with air as possible but there is no doubt that the coffee beans do start losing their aroma and simply cannot compare to coffee which is as fresh as possible. However, coffee which has already been ground really does start to lose its flavour immediately, some estimates put it that up to 45% of the aromatics (which provide the aroma and flavour in the coffee) are lost within 15 minutes of coffee beans having been ground.
Smaller, speciality coffee roasters (you know, the single origin advocates, that want to string anyone up that will even consider blending coffee beans, never mind mixing a bit of robusta with the precious arabica) seem to froth at the mouth about these issues.
Here is an interesting rule of thumb that was recently posted by an afficionado:
"Babbie's Rule of Fifteens:*
Green Beans should be used in fifteen months.
Roasted beans should be used in fifteen days.
Ground beans should be used in fifteen minutes.
Extracted beans should be served in fifteen seconds.
*These are generalities, and depend on the bean, the environment, and your tastes. While there are occasional outliers, anyone that suggests that these are way off would arouse my suspicions. Especially about his tastes..."
Although there are always going to be differences of opinion, let us agree, that the fresher the roasted coffee, the better the taste, and fresh ground is always better than something which has been standing.
So, if you are going to choose a coffee machine, a coffee shop or a coffee bean supplier, you won't go wrong if you do check your facts on the type of grinder/machines and coffee products; such as when does the grinder, actually grind the coffee beans, and how old are your coffee beans when they are delivered to you or the shop?
Remember that imported coffee such as some brand names from Italy, etc, were probably roasted at least six weeks before the coffee even arrived in South Africa. Maybe we should proudly support South African, but that does not mean that all coffee roasters, coffee shop owners or machine suppliers are created equal. Some of the larger roasters though; do roast better than some roaster that only started learning their trade in the last few months and is still continuing their learning process. After all, if the beans weren't roasted properly in the first place; then is doesen't matter when the beans were roasted...
The only thing to do, is to chat to your suppliers or potential suppliers and try to get a feel for their passion for the coffee and equipment which they are selling.