Instant coffee comes in three different forms, freeze
dried, spray dried and liquid concentrate. Although the
initial brewing process is the same for all methods they
vary greatly with the methods used to produce the final
coffee product.
Typically the coffee beans chosen for instant coffee
production are from the lower end of the quality scale,
since many of the subtle flavours and aromas of the more
expensive types are lost in the production process.
Freeze dried coffee was discussed in a different article,
so here we concentrate on the production of Spray Dried
Coffee.
Stage One - This stage involves the production of large
quantities of freshly brewed coffee using industrial bulk
brewers. Freshly ground coffee is put into contact with hot
water in industrial brewers until the desired degree of
extraction has occurred. The process can either be the drip
filter method that many use in the home or an industrial
version of the coffee percolator. A large quality of waste
material in the form of used coffee grounds are produced by
these methods. However these days they are recycled for use
in animal foods, used as organic fuels or processed as
compost.
Stage Two - The resulting coffee liquor liquid is then
concentrated through an evaporation process where some of
the volatile aroma components are removed and stored to be
returned later prior to packing.
This stage produces a thick more viscous coffee liquid that
is then ready for the next stage in the making of spray
dried instant coffee.
Stage Three - The concentrated liquid coffee is then sent
to the spray-drying tower where it is turned into powder.
This is achieved by pumping the coffee concentrate through
an atomizer where it is broken into small droplets. These
droplets react with the hot drying gases in the tower and
lose moisture rapidly. They are are suspended in the drying
air and typically separated by centrifugal action.
The resulting fine powdered coffee can often be too fine to
be used easily. Consequently it often undergoes an
additional process called agglomeration, which results in a
more useable and appealing product. The fine coffee
particles are gathered into larger particles using a
partial re-hydration process which produces a more visually
tempting finished product somewhere between the consistency
of powder and freeze dried coffee.
Spray dried coffee is considerably cheaper to produce that
freeze dried coffee, the latter of which is considered the
more higher quality product.
----------------------------------------------------
For more information about coffee and coffee brewing
equipment visit http://www.cafebar.co.uk
