It is exciting and delightful to own a home espresso machine. We get to explore this new territory of coffee making from espresso machines – tools’ accompaniment, preparation work on grind calibration, tamping, extraction results, final flavour etc.
There are assumptions by many new home espresso machine users regarding coffee extractions, especially when after suitable, catered grind settings for coffee beans were done, consistent tamping technique applied, that coffee extraction results will stay constant and there will be palatable, optimal extraction always. But the reality is, this is not so. Over time, we realized that even with the said factors executed at status quo, ultimately extraction will start to waver, become watery, turn out to be deficient of bursting or enchanting flavours – why is this so? One of the many reasons is due to coffee staling.
For many coffee connoisseurs and the specialty coffee industry, much emphasis is placed on the chemical reactions and properties’ changes that take place after coffee beans are being roasted. These alterations that occur in roasted beans will eventually lead to staling, which brings about a discerning, unpleasant flavour that increases gradually over time. And this affects to a great extent on the final brew quality.
Hence, firstly, to get flavourful, vibrant and good-bodied coffee extractions, the very first criteria is to buy fresh coffee beans. The best time to start using the coffee beans will be on the 4th to 5th day from the roast date, and best to use up the beans within a month’s time.
But having freshly roasted coffee beans is not the end of the story, and it does not guarantee you superlative coffee brew continuously, as fresh beans is only one of the very fundamental parameters, among all others.
In fact, once and when coffee beans are roasted, this triggers the beginning of coffee staling, since roasting creates pressure, carbon dioxide, related chemical reactions such as Maillard reaction, decreases the density and simultaneously increases the porosity of coffee beans. Albeit this initial commencement is at a minimal.
Other Main Factors of Coffee Staling
Higher temperature accelerates the rate of coffee staling both chemically and physically. In comparison to whole bean, ground coffee has twice the higher pace of staling. This is the reason why we always recommend obtaining whole bean instead of ground coffee.
Freshness in coffee chemical compounds decreases with increasing temperature.
Moisture also has a general correlation with coffee staling.
If your coffee happens to be stored in an environment or a place which is highly humid, the coffee will pick up water – water will then dissolve the essential, intrinsic compounds. This hastens coffee beans’ staling, and therefore shortens its shelf life.
Oxygen is an essential element to all human beings, but it is to roasted coffee a prime enemy as it greatly affects its freshness. Oxidation of coffee results in loss of aroma, flat & stagnant flavours.
Once coffee gets into contact with oxygen, the deterioration of freshness begins to occur.
Hence from this, it could be derived that oxygen is the most important parameter that influences the shelf life of coffee. So once coffee bean package has been opened, if the bean pouch does not come with a high adhesive seal, then do place the beans immediately into a tight, vacuumed coffee container.
Minimization on the Pace of Coffee Staling
From the many factors that were said which affect coffee staling, although this phenomenon could not be prevented entirely, still it is possible to minimize the rate of it. To do this, one area to look at is packaging itself.
It has been experimented that quality packages with degassing valves used as roasted coffee bean packings possess the ability to void oxygen to 0%.
Also, vacuum packaging / receptacles / containers can sufficiently protect roasted coffee beans from exposure to oxygen and lowering it by great amplitude.
There is an understanding that coffee could be adequately protected by vacuum packing. And it is very effective in decreasing staling rate to an immense degree. But do note that once the packaging is opened for consumption and usage, the beans are immediately subject to the beginning cycle of staling process.
As per mentioned above, the staling cycle is part and parcel of the life of roasted coffee beans. Staling cannot be totally extinguished, but we can stall the commencement of staling for a longer time. In this way we can prolong the life of roasted coffee beans.
Whole Roasted Bean
It is recommended / best to buy roasted coffee bean as whole beans instead of ground coffee. This is because when coffee is ground, chemical reactions increase at a faster rate. Ground coffee provides a room for heightened pace of degassing and staling since it becomes very much highly porous. Its surface-to-volume hikes, which gives ample area for oxygen and related reactions to bathe in.
The ultimate result will be losses of specific intrinsic volatile compounds that make up the essential aroma and flavours of coffee. Hence the overall shelf life of ground coffee is very much shorter as compared to whole bean itself.
Effective Control of Environmental Conditions
It is mentioned that temperature, moisture, oxygen contribute extensively to the rate of coffee staling. Hence, effective regulation of these will help immensely in slowing down the life span deterioration of roasted beans.
As you can see, the art of coffee extraction is not just solely dependent on espresso machine itself. Unpleasant, rancid coffee flavours, poor coffee texture etc are not what most people think are a result of the degree of machine performance. These are in fact also more often a consequence of the state of freshness of the roasted coffee beans.
Thus prior to obtaining that optimal coffee extraction, we should also look at the very basic ingredient itself – the coffee beans’ state of freshness. Due to the capricious, ephemeral nature of roasted beans, it poses a very challenging task to forecast, and thus to capture the rate of staling, since the quick chemical and physical changes that occur in roasted beans make exact control and solution to staling impossible. But we can still base on the abovementioned factors which affect the pace of insipidity to execute near-appropriate measures to minimize staling – thus prolonging the shelf life of roasted beans.