It is difficult to escape the claims we’re bombarded with on a daily basis about the benefits of fresh coffee: Never serve stale coffee again! the advertisements promise. Nothing is as fresh! claims the storefront sign. Roasted, packed and delivered the same day! says the brochure. the clichés are neverending. What is certain, however, is that each of these claims relies on the freshness-of-roast angle to make or break a sale.

On the flip side of these marketing promises, there remain unanswered questions, such as, how fresh is best? When is coffee stale? And why is coffee best when delivered on the same day it’s roasted? All are valid questions, particularly when we recognize that most large coffee companies do not deliver to market in fewer than eight weeks. They claim that the packaging they use extends the life and freshness of the roasted beans—in some cases, up to two years!

Who are we to believe, and where do we turn to for answers?

You guessed it: science. Combined with a trusty palate and olfactory sense, science can go a long way to settling the issue of freshness of roast. Make that determining when coffee is no longer fresh.

dis•claim•er

A word of caution first: This is not a definitive paper. What you are about to read are conclusions derived from numerous attempts testing the degradation in freshness of roasted coffee against a control model.

These tests ranged from light roasts to dark roasts, from 100-percent arabica to arabica/robusta blends, from varying lengths of time exposing coffee beans to air from the time of roasting, to all forms of packaging, to pressure-filled, vacuum-sealed, nitrogen-flushed methods, and to various environmental conditions affecting the storage of coffee. Keep in mind that the yardstick for measuring freshness of roast is the rate and time it takes for a coffee blend to degas.

Degassing is a kinder way of saying ‘decomposing.’ Once roasted, coffee immediately goes into a state of decomposition—quite rapidly in the beginning, diminishing to almost zero over time. At zero, coffee can be categorized as stale. However, the disclaimer here is that the time it takes to degas varies according to all the factors mentioned earlier—environmental conditions, packaging variations, etc. Visual, palate and olfactory analyses best determine when degassing is final. In other words, we must be able to understand what stale coffee looks, smells and tastes like..

from the heat to the dry•ing tray

The roasting process triggers chemical reactions in the beans which go on to establish the development of flavor, aroma, body, crema, and other characteristics unique to the particular beans. These reactions are quite vigorous at first, and as we recall from our days of science at school, all chemical reactions give off byproducts. In the case of coffee, the byproduct is carbon dioxide or CO2.

And since there is a great deal of activity immediately after roasting, coffee beans can be categorized as ‘alive’ or fresh. Ironically, though, coffee is too ‘alive’ in the immediate period after roasting, and therefore should not be used for a predetermined amount of time. Batches must undergo a period of rest prior to use. In order to mature, coffee must settle in a protective environment, much the same as red wine eases into its true and best character. And sadly, this is a fundamental flaw of many roasters and baristas. They lack the understanding that coffee that is too fresh is not ideal for use, particularly as espresso. Roasted coffee beans need time to settle somewhat, time to develop persistent crema, rounded body and complexity of flavor. In other words, they need time to get better.

However, coffee beans will not undergo this maturation phase if they are exposed to air for an inconsiderate period of time before being packaged. Once out of the roasting machine, the longer it takes the beans to cool affects the ultimate life span of freshness in the roast. The longer the length of time it takes to encase the coffee beans in a protective environment, the shorter the period of freshness for the coffee. Of course, like red wine, the storage environment the packaged coffee is then put into also plays a part in extending or reducing this freshness window.

“Protective environment” is in reference to appropriate packaging material. The point is to prevent the wonderful sugars and elements essential to the favorable makeup of the espresso from being oxidized. Exposure to our atmosphere and the air we breathe creates oxidization, and degrades the chemical structure of all the essential components necessary for the creation of a spectacular espresso.

Also, dark roasts degas faster than light roasts, and 100-percent arabica beans degas with a lesser volume of CO2 than arabica/robusta mixes. Further, if the coffee beans are stored in a hot environment, they degas faster than when stored in a cool environment like that of a wine cellar. All these scenarios affect the rate of degassing, and therefore the shelflife, or freshness, of the coffee beans.

un•der•stand•ing pack•a•ging

Take plastic-coated paper coffee bags, for example. The roasters who use this form of packaging tend to be convinced that it is the ideal form of casing for coffee beans. However, plastic-coated paper coffee bags, although trendy and stylish, cannot prevent oxygen from permeating through the lining and attacking the coffee beans.

Try this simple experiment to prove this point beyond doubt. Take a paper coffee bag filled with water and copious amounts of red dye, and suspend it in a bucket of water for a day. Come back to it, and you will find the red dye has leaked through the bag and into the water in the bucket. If dye molecules, which are bigger than oxygen molecules, can get through the packaging, what does that say about the shelflife of the coffee beans?

Any material used to pack roasted coffee must block oxygen from permeating through its ‘skin.’ Vacuum sealing this type of packaging reduces oxygen in the package down to around two percent. (Oxygen in our environment is approximately 21 percent.) Nitrogen flushing can displace all but 0.2 percent of oxygen. Furthermore, nitrogen is an inert gas that promotes the ‘protective environment’ required for coffee beans to mature.

Assuming that the packaged coffee beans go on to be stored in a wine cellar-type environment, they have the potential to remain fresh for up to three or four months. Of course, coffee tasted during the latter half of this timeframe will exhibit noticeable effects of degradation, namely reduced sweetness, reduced crema and an increasingly bitter aftertaste, among other things.

Transporting coffee in a hot or humid environment will cause the coffee beans to sweat, increasing the rate of degassing, and causing the oils which appear on the surface of the bean due to sweating to turn rancid. This, of course, also reduces the shelflife of the coffee.

noth•ing is ex•act

It is the uniqueness of coffee, however, which prohibits clear definition of these time frame. With more than 1500 chemical compounds—most of which have yet to be fully understood—and a complexity that is second only to wine, it’s virtually impossible to determine the amount of time in which it takes freshness in coffee to disappear. I have tasted ‘stale’ coffee less than two months after roasting, and ‘fresh’ coffee more than six months after roasting.

Without the accuracy of scientific measuring equipment, the best a barista can hope for in defining freshness of roast is a generality. All we have at our disposal are our eyes, noses and palates—but don’t discount them. While highly subjective on their own, sight, scent and taste become a powerful array of analytical apparatus when used in concert.

It is impossible to ignore the olfactory experience when calculating whether coffee beans are fresh or not. True, the chemical compounds in the coffee beans do not diminish in number or change state under a microscope. But it is not clear why well-trained eyes, noses and taste buds can determine a difference between fresh and stale coffee. Whatever the reasons, however, they work.

For example, it is not possible to extract a ‘fresh’ espresso full of flavor, body, sweetness, and in possession of a three-dimensional profile without favorably stimulating the olfactory system. In understanding why, it all goes back to science.

dis•ci•pline & da•ta

Our taste buds are capable of detecting a basic array of tastes, including sweet, sour, bitter, salty, and astringent. Taste buds are limited in their ability to detect these tastes when compared to the olfactory system, though, which can, in fact, decipher thousands of chemical aromas. Our notion of flavor is primarily a result of the smell of gasses being released by the chemicals we have put in our mouths.

Volatile gasses from substances are released by the act of chewing, sucking or drinking. These gasses flow out of the mouth and up the nostrils—or up the passageway in the back of the mouth—to the olfactory epithelium, located between the eyes behind the base of the nose. The brain then combines these complex smell signals from the epithelium with the simple taste signals from the tongue, and assigns a flavor to what’s in our mouth. In terms of espresso, this provides us with enough information to determine whether the drink is what we want and whether it is fresh or not. It’s assumed that when coffee is fresh, the beans release more volatile gasses and that stale coffee struggles to produce any gasses at all.

Prior to drinking, coffee in espresso form can be visually inspected for freshness. If the coffee extracted has color, is thick and honey-like to the eye, and is loaded with espresso, we can assume that it is fresh. If the crema is like the head on a cola, with lots of large bubbles and rapid dissipation, the coffee is too fresh. But if the crema has fine micro bubbles, is persistent and projects depth, we can assume the espresso is fresh and stable. And if all we see during extraction is black water, with little or no crema, along with a pale color, we can assume the coffee is stale. Of course, throughout these visual analyses, particular pleasing or not-so-pleasing aromas can also indicate the state of the coffee.

Whatever pathway a batch of coffee takes, we are beholden to determine the freshness of the product through the use of sight, smell, taste, and our good old-fashioned powers of deduction. This can be done with the use of only one of these faculties given proper training on what to look for. But using all the senses together is best; if you know your coffee, it’s difficult to miscalculate freshness using sight, smell and taste combined.

What’s critical is a commitment to learning through experimentation and logical deduction. You will not know fresh until you taste coffee just roasted. You will not know stable until you see and taste what unstable is. You will not know mature coffee until you taste stale coffee. And you will not know the freshness of roast you prefer unless you parcel off a batch of coffee in various packaging and taste a sample every day over many days.

Of course, after you’ve come to understand all these factors, you will just start all over again, for our profession is all about learning and relearning and learning again.

Ready to finish the story? Then order this back issue today from Barista Magazine!