2.
Quality and Weight loss Coffee
Over-dried bean: By weight, you can lose 3% or more of their harvest
Drying temperature too high: you can lose quality. They have found missing from 3% to 15% of their harvest
3.
SUN DRYING ( UNCONTROLLED VARIABLES)
Weather: Thick clouds, rain, sunlight spectrum .
Thick clouds: slow drying, rising coffee layer for lack of space, possibility of mold.
Rain: rewetting causes dissolution of soluble compounds of the grain, which the turn
brown when oxidized by the action of air.
Sunlight spectrum: the temperature control is of paramount importance, because, if it
exceeds the critical value of 40 C, particulary if it reaches 70 C, fermentations
start with formation of stinker beans. It has been observed that sunlight, especially
in the spectrum range between 400 and 480 nm, plays an important role in
maintining coffee quality. This effect is confined to the final phase of the black stage
therfore drying could start in the dryer, be continued in the sun between 40 and
20% moisture, and be completed in the dryer.
Reason for losing the quality
4.
SUN DRYING ( CONTROLLED VARIABLES)
Variables that can be controlled, but often ignored; causing damage to the quality of coffee:
When parchment beans are spread out to dry on patios, the layer should not no be higher
than 3-5 centimetres and be frecuently mixed, epecially during the initial drying period,
otherwise the parchment will crack, causing an early exposure of the bean.
The next variable, is highly missed:
Once 50% of the water has been eliminated, heaps should be made and covered with
wax cloth. At midday these heaps should be dismantled and exposed to the sun for 2-3
hours. Normally coffee is exposed to the sun for 7 hours.
Other varaiables: coffee without mixed, unclean patios, wet coffee piled.
Reason for losing the quality
5. MACHINE DRYING OF COFFEE BEANS (UNCONTROLLED SAFE
TEMPERATURE
LIMITS)
During the process of drying the coffee, safe temperature limits are not controlled; try
to control them through the drying air temperature, which is not appropriate and safe.
If should be clearly understood that to specify a temperature limit alone is not enough.
The time during which the coffee is maintained at a given temperature is just as important
in its effect on quality. Since conditions in different types of driers vary greatly, and since
coffee temperatures are constantly moving up or down, temperature programming even
in the same type of drier varies with different operators. In addition, the course of the
drying may be interrupted by moisture equilibrating rest and storage periods in which
neither heating nor drying goes on. It is even less meaningful to specify drying air
temperatures because coffee temperatures may be very different from air temperature
especially at the beginning of drying when the cool coffee has entered the drier and
is losing moisture rapidly which results in evaporative cooling.
Reason for losing the quality
6.
MACHINE DRYING OF COFFEE BEANS (UNCONTROLLED SAFE
TEMPERATURE LIMITS)
At times, the outside of the coffee beans may be considerably warmer than their
centers. OVERHEATING DURING DRYING PRODUCES SOUR OR COOKED
FLAVORS IN THE BREWED COFFEE.
As an approximate guide, it may be stated that coffee will tolerate temperatures of
104 F (40 C) for a day or two, 122 F (50 C) for a few hours, and 140 F (60 C) for less
than an hour without damage. For this reason we say that is the temperature of the
coffee bean must not exceed 104 F (40 C), but this is a very empirical control, and
exposed to operator error.
Reason for losing the quality
7.
To avoid damage to coffee by the above factors, it is best drying in driers with good
control.
In establishing the best drying conditions for any drier, certain general principles of drying
apply. Three factors make for high efficiency and low cost together with good control of
coffee quality.
1. The greatst possible production capacity from available equipment, obtained by
operating at the highest temperature consistent with good cup quality. This implies
good temperature controls (especially coffee temperature) and accurate sensing elements.
The maximum speed of drying is produced by high air flow, but this limited by maximum
flow that may be used efficiently; otherwise, power fan, and duct capacity may be wasted.
2. High heat efficiency which minimizes fuel consumption. This is obtained by minimizing
heat losses caused by heat and air leaks and by using partial recirculation of the moist
exit air if the desing of the drier permits.
Optimum drying conditions
8.
3. Labor economy, obtained (a) by using a few drying units of large size rather than he
reverse, although flexibility to meet fluctuating coffee flows must no be overlooked, (b)
by making full use of material handling machinery to move the coffee, and (c) by using
automatic controls for temperature of coffee, temperature and relative humidity of the
drying air.
GOOD DRYING COFFE, WE GET BETS QUALITY AND WEIGHT, YOU DO NOT
LOSE MONEY.
Optimum drying conditions
9.
Espresso Coffee
The chemestry of quality, edited by: Andrea Illy and Rinantonio Viani
Coffe Technology
Michael Sivetz, Ch. E.
El Beneficio del café
René Wilbaux
Coffee: Growing, Processing, Sustainable Production
Edited by Jean Nicolas Wintgens
My experience for 32 years since 1982.
Roberto Mojica Moreira
References
