What is Freeze Dried Coffee?

What is Freeze Dried Coffee?
Most people given a choice would prefer the taste of fresh
ground coffee rather than instant freeze dried coffee but
nonetheless the freeze dried coffee market is vast both
domestically and commercially.

It's sheer convenience and ease of use is probably its main
advantage and with the improvements of modern production
processes the flavour of the final beverage has improved
dramatically. Just add a spoonful of freeze dried coffee
granules to a mug, add hot water and you can enjoy a decent
cup of coffee.

We have all probably drunk freeze dried coffee at some
stage, but what actually is it and how is it made?

Initially fresh brew coffee is made in the usual way using
a very large industrial bulk brewer in which very hot water
is passed though fresh coffee grounds in a filter system to
produce the hot coffee liquor we are all familiar with.

This coffee liquor is then concentrated through a series of
evaporators under vacuum where some of the aroma and
flavour compounds are also removed and stored. This ensures
that some of the flavour and aroma of the coffee that is
lost during the freeze drying process can be 'put-back'
into the final product just before packing.

The concentrated coffee liquor then moves on to the actual
freeze-dry processing equipment. Here the coffee liquor is
initially foamed and then frozen to a temperature of -450
degrees centigrade. It is then ground to the required
particle size.

The ice crystals that formed in the freezing process from
the water content in the beverage are then removed in a
process called sublimation. Here the frozen granules are
subjected to a high vacuum which results in much of the
water ice content to be transformed directly into gas
(without a liquid stage it would normally undergo) before
being returned to room temperature.

The resulting freeze dried coffee typically contains just 3
to 5 percent water. The more volatile flavour and aroma
compounds extracted at the initial brewing stage are then
returned to the dried product just before packing.

As you can imagine an industrial factory producing freeze
dried coffee produces vast amounts of used coffee grounds
in the production process, but these are not put to waste.
They are usually sold on as animal feed, compost or organic
fuel.

It should be noted that freeze dried coffee is different
from spray dried coffee and is generally accepted as
superior in quality. The spray dried production of coffee
will be the subject of another article.

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For more information about coffee and coffee brewing
equipment visit http://www.cafebar.co.uk