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the first step is thorough cleaning of defective beans and separation of nails, stones, dirt & dusts. blending of beans is carried out before roasting by installing volumetric feeders at the outlet of the silos. through this process various kinds of blends are obtained depending on the taste and demand of the market.

 

green coffee cleaning

roasting of coffee beans develops the flavor and aroma which depends on various physical & chemical changes which occur during roasting. degree of roast & roasting temperatures are very important and plays an important role in deciding the flavor and colour of the final product..coffee roasting cum grinding unit

3. coffee extraction system

the third step is extraction of ground coffee through a continuous process in a pressurized vessel with hot water. to get a better yield seven batteries of counter column extractor cell is used featuring extraction under closely controlled system. extraction is greatly influenced by factors like type of green coffee beans, degree of roast, type of grind, ratio of coffee to water & mode of heat input.

 

      coffee extraction

 

the extracted coffee solution is passed through a centrifugal clarifier to separate the insoluble solids.

clarification unit

this is done after clarification extracted coffee liquor is passed through the aroma recovery cum evaporation plant. in the plant, the volatile aroma is stripped off from the coffee before it enters the evaporator. based on the boiling points of the aroma constituents gte ltd has developed a new technology for the extraction of this aroma without diluting them with the water vapours so the result is more pure and concentrated aroma. this technology is called the arc system which stands for aroma recovery cum concentration system which is integrated with the evaporation system. in the evaporator concentration of the extract is done through multi-effect evaporators with tvr systems for concentration up to 50-55%. it is possible to concentrate the extract further up to 65-70%, to reduce the load on freeze drying system.

 

 

                                    aroma recovery unit

the next step is concentration of the extract through multi-effect evaporators with tvr systems upto 50% concentration is achieved.

                      evaporation section - part 2 calandrm section

 7. spray drying system

the concentrated coffee is then converted to instant coffee powder by spray drying. drying is done under controlled conditions to protect and preserve aroma and flavor in the coffee.

 

 

 spray drying section

 

8. agglomeration system

lastly, the spray dried powder can be converted into soluble (instant) granules in an agglomerator tower by re-wet agglomeration technique. this technique results in the formation of bigger sized porous particles and reduces the bulk density thereby increasing the instant ability of the powder. hence when a spoon of this agglomerated powder is put in water, it disperses completely due to the osmotic pressure of the liquid.

                                      agglomeration section

 

 

 

 

 

 

9. packing & filling

the instant coffee powder is then taken to the tote-bins for storage and packing. for filling into tins or jars, vacuum operated filling system is used. for filling into sachets, a form fill-sealing machine is used. the filled containers/flexible packing are packed in the shipping cartons and sent for dispatch to the finished goods warehouse.

unique features of instant coffee plants

·         integrated evaporation and aroma recovery system, both of which can be controlled from one plc.

·         saves lot of energy as pre-heating is carried out with generated vapours in the evaporator.

·         the system provides aroma at a higher concentration and is not diluted with water vapours.

·         availability of concentrated aroma allows higher concentration feed to spray dryer, which increases productivity.

·         unique agglomerator design ensures stronger particle with less fines.

·         aroma recovery system consists of rotating stripper column which makes it sturdy and easier to handle.

·         evaporators are most energy efficient. in a 5 effect plant with tvr the specific steam consumption is 0.12 kg/kg, i.e., 1 kg of steam evaporates 8 kgs of water.

·         flexibility in agglomerator for obtaining required bulk density

unique evaporator design ensures:

·         highest energy efficiency.

·         high product quality.

·         compact design.

·         easy operation & automatic control.

·         low operation cost.

unique spray dryer design ensures:

·         flexibility in controlling powder quality and production of instant powder.

·         less down time for maintenance purposes.

·         possibility of expanding capacity upto 100%.

·         gte ltd has supplied more than 50 spray dryers; the biggest one is having a powder output of 38 tpd.

instant coffee powder is usually made by evaporation of coffee extract upto 40-45% concentration by use of an evaporator followed by spray drying at a high temperature (180-220 °c). this results in change in appearance, colour, loss of aroma and taste.

however, use of freeze dryer retains aroma, improves appearance and taste because freeze drying takes place at a low temperature which minimizes heat damage and retains volatile components (aroma). it also increases the shelf life of the dried product as compared to standard drying practices.

freeze-drying involves dehydration of food products at low temperature and pressure. as a result only the moisture is removed, leaving the molecular structure intact. the end product is light in weight with least or no change in volume. worldwide freeze-drying technology is considered as the ultimate amongst all other dehydration methods. hence this technique is currently being used for the production of instant coffee. 

in a freeze drying system, concentrated coffee (42-45%), is first freezed and then exposed to a low partial pressure (4.6 mmhg) of water vapour when ice sublimes directly to vapour leaving behind dried coffee.

freeze drying is an expensive process in terms of capital, expenditure and operating cost but results in excellent product quality.

freeze drying of coffee involves four steps:

pre-freezing coffee concentrate up to -5 / -10 °c followed by foaming.
freezing of the prefreezed coffee liquor at -50 °c in a blast freezer.
sizing of the freezed coffee particles to a granular size of 3x3mm.
sublimation of the ice in a vacuum freeze dryer (vfd) under vacuum (0.5 torr) and controlled temperature.

gte ltd has developed this technology successfully in their r&d laboratory, where a pilot plant has been set up for demonstration.

advantages of freeze dryers are:

·         continuous plant, which needs less space.

·         most energy efficient.

·         minimum heat damages, which helps in retaining good appearance and colour of the product.

·         retaining most of the aroma due to the use of most innovative aroma recovery.

·         quick and complete re-hydration due to porous structure (instant)

·         less man power requirement (fully automated)