Coffee Bean Storage
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Coffee bean storage is a broad term describing the packaging and preservation of
coffee beans A coffee bean is a seed of the ''Coffea'' plant and the source for coffee. It is the pip inside the red or purple fruit often referred to as a coffee cherry. Just like ordinary cherries, the coffee fruit is also a so-called stone fruit. Even thou ...
throughout the process from harvesting to brewing. Although the term is applicable to many phases of this process, it is typically applied to ideal home storage for maximum consumer coffee enjoyment.


Green coffee

After the cherries are put through the
pulper In agriculture, a pulper is a machine designed to remove pulp (i.e. the soft flesh) from agricultural produce. For example, in coffee growing the ripe red cherries are picked from the coffee bushes and before fermentation and later drying the sof ...
and the seeds have been soaked, they are set out to sun-dry for a period of one week. The beans are periodically raked to ensure even drying. Once dried, the beans will form a thin, paper-like shell called parchment. Once formed, the parchment will increase the beans’ storage life considerably. When the beans are ready, the parchment is removed, and the beans are graded and sorted according to size, weight, and defects. The sorted beans are then stored in 60 or 70 kg sacks called
sisal Sisal (, ) (''Agave sisalana'') is a species of flowering plant native to southern Mexico, but widely cultivated and naturalized in many other countries. It yields a stiff fibre used in making rope and various other products. The term sisal may ...
bags that help the beans retain moisture for a longer period of time., "Hollandbymail.com", retrieved 2/2011 The storage time cannot exceed one year for the beans to be considered a current crop. If the green coffee remains in storage for longer than a year, it is considered an old crop and is less valuable because of its drier state.


Roast coffee

Once a coffee bean is
roasted Roasting is a cooking method that uses dry heat where hot air covers the food, cooking it evenly on all sides with temperatures of at least from an open flame, oven, or other heat source. Roasting can enhance the flavor through caramelizati ...
, it is either packaged immediately for sale or ground and then packaged for sale. Packages used are typically either an airtight
plastic container Plastic containers are containers made exclusively or partially of plastic. Plastic containers are ubiquitous either as single-use or reuseable/durable plastic cups, plastic bottles, plastic bags, foam food containers, Tupperware, plasti ...
or vacuum-sealed wrapping, or a folded-over bag with a pressure
relief valve A relief valve or pressure relief valve (PRV) is a type of safety valve used to control or limit the pressure in a system; pressure might otherwise build up and create a process upset, instrument or equipment failure, or fire. The pressure is r ...
. Each type of package has its own advantages. The airtight containers allow the maximum freshness of the bean and prolong its shelf life, whilst the valve allows excess
carbon dioxide Carbon dioxide ( chemical formula ) is a chemical compound made up of molecules that each have one carbon atom covalently double bonded to two oxygen atoms. It is found in the gas state at room temperature. In the air, carbon dioxide is t ...
, and other gases to escape. The carbon dioxide, as much as 10 L/kg of coffee for dark-roasted coffee, is not released because it is harmful to the flavour—quite the contrary, it protects the beans against oxidation, but excess pressure could damage the container. Reported experience is that a few days of carbon dioxide release is needed between roasting and brewing for best results. There is also informed opinion that storage of freshly roasted beans in a can pressurised with nitrogen gas, with excess pressure buildup vented via a relief valve, provides optimal storage for extended periods while promoting a beneficial ageing effect related to the distribution of natural oils by the pressure.


Home storage

Once bought, the method of storage used depends on the type of coffee purchased. Green beans store the best in cooled airtight containers, and can easily last in this state for a year without losing flavor. Roasted whole beans are best stored in airtight containers out of the light. The best material choices for the container are
ceramic A ceramic is any of the various hard, brittle, heat-resistant and corrosion-resistant materials made by shaping and then firing an inorganic, nonmetallic material, such as clay, at a high temperature. Common examples are earthenware, porcelai ...
, or opaque glass. Plastic and metal may alter the flavor of the coffee bean. In addition, for the first week of storage, containers should be opened or vented by a relief valve to release the carbon dioxide gas that will be produced by the roasted beans to prevent the gas from changing the quality of the coffee. Whole bean roasted coffee stored in this manner will last for about two weeks. The advisability of freezing roasted beans is controversial. Those advocating freezing believe that the flavour can then last for one to two months. If beans are frozen, leaving them frozen until
brewing Brewing is the production of beer by steeping a starch source (commonly cereal grains, the most popular of which is barley) in water and fermenting the resulting sweet liquid with yeast. It may be done in a brewery by a commercial brewer, ...
best preserves the flavour of the coffee. Frozen beans will grind the same as unfrozen beans, but refreezing beans alters the quality of the coffee. Coffee grounds are stored in metal containers that are non-reactive airtight ceramic or glass containers, like roasted beans. Due to increased total
surface area The surface area of a solid object is a measure of the total area that the surface of the object occupies. The mathematical definition of surface area in the presence of curved surfaces is considerably more involved than the definition of ...
of coffee grounds, the grounds go stale in days, rather than weeks. In addition, freezing has no effect in increasing the storage life of coffee grounds.


References

{{Coffee Coffee production Edible nuts and seeds