Instant coffee production

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1. GENERAL DESCRIPTION:


1. General Flowsheet of instant coffee production


Dyring in chocolate production, figure1.jpg


Figure 1: Flowsheet of instant coffee production

Literatur: Ullmann's Encyclopedia of Industrial Chemistry, Vol.A7, 1994:


2. Description of techniques, methods and equipment
(Ullmann's Encyclopedia of Industrial Chemistry, Vol.A7, 1994):

Roasted coffee is either sold as whole beans, ground for brewing and immediate consumption, or further processed at the coffee plant where after extraction, the soluble solids are concentrated and dried to produce instant coffee. The manufacture of instant coffee follows the process described below:


(a) Extraction:
In an instant coffee plant, coarsely ground coffee is extracted with softened water in a battery of 5-8 percolation columns, with cell capacity from a few kilograms up to 1t. The process operates semi-continuously, with water at 160-180°C passing as a countercurrent to the coffee from the most extracted cell to the one just filled with freshly ground, roasted coffee. Extract is withdrawn from the last cell, cooled to 4-5°C in a heat exchanger, and then sent into a scale.


(b) Concentration:
Extract at a concentration of 30% or more can be dried directly, but with a high loss of aromatic constituents. The extract coming out of the hot section contains fewer volatile aromatic constituents than cold extract. The hot extract can be evaporated to a concentration of 50-60% after flashing or steam stripping the volatile aroma or by separating hot from cold extracts; it can be mixed then with diluted aroma or cold extract to reach a standardized extract at ca. 40% concentration. A more gentle concentration process involves freezing the extract and then mechanically separating the almost pure ice crystals. By this technique, coffee extract can be efficiently concentrated up to 35-40% with relatively low flavor or product losses.
(c) Drying:
There are mainly two different ways of drying the extract in the instant coffee production:
1.) Spray-drying
2.) Freeze-drying
During this operation, extract is frozen with separation of ice crystals, which are then sublimated under vacuum. The process entails several steps:
  • Primary freezing:
  • Secondary freezing:
  • Grinding:
  • Drying:


(d) Aromatization:
Volatile aroma from grinding gas or from steaming of ground, roasted coffee prior to extraction is emulsified with oil from pressed, roasted coffee or spent grounds and sprayed on the powder, at a level of 0.3-1% during the filling operation.


3. Temperature ranges and other parameters (table)
(Ullmann's Encyclopedia of Industrial Chemistry, Vol.A7, 1994):


Instant coffee, table1.jpg


4. Benchmark data


2. NEW TECHNOLOGIES:


a) Changes in the process


b) Changes in the energy distribution system

Waste heat re-use in instant coffee manufacturing: (BAT in the Food, Drink and Milk Industries, June 2005)

a) Description of the technology:
The instant coffee manufacturing process is highly energy intensive. Waste heat, e.g. from the extraction unit and air compressors, can be re-used during production, e.g. for extraction, and as a heating source, e.g. in offices and storage areas. A standard procedure for waste heat utilization is also the recirculation of partial steams of exhaust air within the installation such spray drying, e.g. using countercurrent heat-exhangers and within the roasting sector. Reduced energy consumption is accomplished in this way.
b) Description of suitable energy supply systems:
A circuit of heat exchangers and tanks is needed to achieve the heat transfer. Electrical energy will be consumed to operate the pumps of the circuit.
c) Possible energy savings reachable by those measures:
No information available.
d) Economic evaluations:
Reduced energy costs.


c) Changes in the heat supply system


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