Air Roasting Process
To help you further understand and appreciate our specialty hot-roasted
coffees and espressos, here are some excerpts from the book, COFFEE
QUALITY, by Michael Sivetz, the inventor of the hot-air roasting
of green coffee beans develops the coffee
aromas and flavors. Roasting is the process of heating the coffee
beans uniformly, first to remove the moisture (about 12%) then to
cause pyrolysis of the sugar in the bean cells, which means that
the sugars break down to caramel, water, carbon dioxide, and many
aldehydes and ketones which characterize the aroma and taste of
The roast weight
loss is related to bean color and beverage taste, and is often related
to the mode of brew preparation and cultural taste. Different coffee
beans react differently to the various end temperatures cited. And
various green beans have preferred levels of roast for best flavor
developments. In the USA, too many firms roast their beans too lightly
because that gives less weight loss (greater yield and profit).
Often roast level is determined by the coffee buyer-taster who is
used to evaluating green coffee beans at light roasts. The end result
of such light roasts can be a very acid, astringent, harsh-tasting
beverage which does not have optimum flavor development. It is a
wasted coffee sold to the public.
Few people realize that the manner of roasting has a great deal
of influence on the taste of the final roasted beans. For example,
rotary steel cylinder roasters, which are traditional in the trade;
e.g. Probat in Europe, due to their high operating temperatures
(over 800 degrees Fahrenheit) cause searching of the beans, oil
release that can coat all the beans, and smoke from burning chaff
that fumigates the beans, giving them a harsh, biting, and (in dark
roast) a burnt taste which is "dirty". The use of Melitta
filter paper, for example, helps remove some of this bitey taste.
It is far better not to scorch or burn the beans or lay a tar coat
on the bean. In order to avoid this scorching and non-uniform roasting
of coffee beans, Mike Sivetz developed, in 1975, a fluid bed "once-thru-air"
coffee bean roasting machine that produces a clean "tar-free"
non-biting, smooth tasting beverage.
Further, the Sivetz fluid bed roaster, with thermal bean sensor,
is the only roaster that can measure true bean temperature, because
the probe is in a stationary box containing the fluid bed of beans.
This accuracy cannot be directly achieved by rotary cylinder machines
due to the pure mechanical difficulty of probing a moving mass.
You are truly receiving the best possible product available in the
The Sivetz hot-roaster allows each bean to develop its naturally
distinctive flavor without the smoke and tar contamination that
occurs in many roasters.
||excerpts from Coffee Quality by Michael Sivetz
1987, pp 35 and 36
Sivetz Coffee Inc.
349 SW Fourth Street
Corvallis, Oregon 97330