Why Coffee Goes Stale

WHY DOES COFFEE GO STATED?
Coffee is a shelf-stable product, meaning it won't spoil or rot like other foods. However, over time it will undergo changes that will cause it to become stale.
But why is this happening? Coffee has different oils, acids, and chemical compounds known as "soluble". They develop during the roasting process and give coffee its unique flavor and aroma when brewed. Unfortunately, as roasted coffee comes in contact with air, oxygen begins to degrade these solubles through oxidation.

Oxidation occurs when the oxygen molecule steals electrons from another substance. Iron, for example, rusts and deteriorates due to this loss of electrons. The avocado in your fridge is succumbing to the same process and will soon taste pretty bad :)

OTHER THREATS

Unfortunately, oxygen isn't the only threat to your coffee. Here are a few more things to avoid:
Heat:
At the microscopic level, heat agitates atoms and accelerates all activity, including degradation. Leave a can of milk in a warm room and you'll see how fast it spoils. Similarly, placing coffee near a heat source accelerates its staling.
Light:
Since heat is on our list, any light source should be avoided. Do not store your Coffee Beans near a window where they will be exposed to hot sunlight. Also, the ultraviolet spectrum is damaging to all organic matter.
Moisture:
Roasted coffee beans are porous and become hygroscopic, meaning they easily absorb the surrounding water, including moisture from the air. Since moisture dilutes all the oils in the coffee bean and changes it to the outer layer, it comes into contact with oxygen faster and evaporates.

STORING COFFEE
We now know that you need to protect your coffee from oxygen, heat, light and humidity. So where to keep them?
As a general rule, in a dark and cool place. Here are a few options:
1) Original packaging:
Miracle! Your coffee's packaging can be good enough as long as it meets a few criteria:
Foil inner liner: A foil lined bag prevents any moisture, odor, gas or light from penetrating through the walls. A paper bag cannot prevent them.
One-way valve: Freshly roasted beans release large amounts of CO2. If the bag were completely sealed (without a valve), the gas buildup would inflate it and it could burst. The valve lets carbon dioxide out and prevents oxygen from entering.
Ziploc-top: This allows you to reseal the bag.
The packages we use in all the schiller coffees we use here comply with these standards. So, just follow these easy steps:

Subtract the amount of coffee you will use immediately.
Reseal the package with Ziploc-top.
Squeeze the bag until all the oxygen inside comes out of the valve.
Once the seeds are opened, they should stay fresh and tasty for about a month.

2) Third-party container:
The container must be opaque and airtight. Ideally, it can push out any oxygen and moisture, creating an internal vacuum.
Whatever the choice, be sure to wash the container before refilling the coffee beans, as coffee beans have oils that will harden over time. Any residue left on the walls can contaminate the new cores.

BUY THE RIGHT QUANTITY
The best practical advice we can give you is to buy the right amount. Freshly roasted coffee will taste great for about a month as long as you follow the steps discussed earlier. So, if you only buy a 30-day supply, you'll always have the ability to brew fresh coffee.

BREW COFFEE

If you decide to buy coffee in bulk, one way to preserve it is to freeze it.
Remember when we said that heat accelerates molecular activity? Cold does the opposite.
For example, as water cools, atoms start to move slower and slower. When the temperature reaches 0°C, they move so slowly that they can no longer escape their gravitational pull. Bonds form between them that hold them as solid ice.
Likewise, freezing temperatures will slow down all molecular activity, such as pausing in coffee beans.
However, you cannot use just any container. Freezers are so humid that the beans absorb this moisture easily. Therefore, you will need to use vacuum sealed bags. Only by completely removing all the air can you freeze coffee safely. Just remove what you're going to use the next morning and vacuum the rest again.
We know how important our morning brews are, so protecting your freshly roasted coffee beans from oxygen, heat, light and moisture is essential.
You can prolong its flavor and aroma by storing your coffee in a cool, dry place, in its original packaging or in an opaque container.
However, always try to buy the right amount. By purchasing just one month's worth of coffee, you don't have to deal with old beans.