24 food Marketing & Technology • June 2013

Processing

The production of instant (soluble) cof-fee involves many process steps. Since the procurement of green coffee beans is the main direct production cost, the quantity of beans required to produce one weight unit of end-product is a key cost factor. The latest coffee extraction technology from SPX has been shown to give the potential to use fewer green coffee beans compared to conventional extraction technology, offering substan-tial savings in production costs.

Instant coffee production processWhen the green coffee beans are deliv-ered to the coffee plant, the beans are cleaned and stored. When required, the blended coffee beans are roasted and ground to the correct particle size range needed for extraction. A fully automated filling system is then used to charge the extractor / percolator under a slight vacuum.

High Yield Coffee Extraction Technology

Figure 2: Instant coffee processing line for premium quality coffee

Figure 1: SPX e&e Coffee evaporation plant

Finely ground coffee results in a more efficient extraction process. If, however, the grounds are too fine, the resulting pressure drop over the percolators be-comes too high and there is a significant

risk of filter blockage. The SPX high yield extraction system provides a total of twelve percolators configured in two rows of six (Figure 2) These specially-designed percolators have cylinders

Processing

25food Marketing & Technology • June 2013

which are wider and shorter than a conventional percolator design, which enables more finely ground coffee to be used while limiting the pressure drop created, resulting in better extraction capability and premium aroma qual-ity. Specially designed top and bottom filters on the percolator further enable extended running times and minimize the risk of filter blockage.

Prior to commencement of the actual extraction process with water, the cof-fee within each percolator is steam stripped to recover the desirable and most volatile aroma compounds. The resulting steam is condensed and stored under chilled conditions. For premium coffee extract quality, an initial low temperature, lenient extrac-tion phase is then initiated to obtain

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an aroma-rich extract. A second stage then uses high temperature to produce high yield, hydrolysed extract. Unde-sired tastes, or ‘off-flavors’, formed in the secondary extract by hydrolyzation are effectively removed by a flash sep-aration process in a vacuum vessel to further improve coffee extract quality.

The aroma from the low temperature aroma-rich extract is recovered, condensed and stored under chilled conditions along with the aroma recovered by steam stripping. The secondary hydrolyzed extract is cleaned in a high-efficiency centrifuge to remove non-soluble solids / sedi-ments and then concentrated in either a multi-effect falling-film or plate heat evaporator. The recovered aromas are then mixed with the concentrated

coffee extract from the evaporator to the desired aroma quality and solid content. Due to the high viscosity of the concentrated coffee extract, in-line mixing with the aroma extract is recommended to ensure good mixing with uniform concentration.

To produce the final instant coffee the extract is either spray dried or freeze dried. Spray dryers are used to pro-duce an end-product in powder form with good soluble properties, whereas freeze dryers produce an end-product in granular form with a low fine par-ticulate content. Both dryer designs enable the instant coffee manufac-turer to control essential end-product properties i. e. bulk density, residual moisture content, powder morphology and color.

Processing

26 food Marketing & Technology • June 2013

When using a freeze dryer an initial pre-freezing and foaming stage is utilized to cool the coffee extract down to the point where ice crystals start to form. A dos-ing system then adds CO2 or nitrogen gas for gasification for bulk density and color control (the release of the inert gas when hot water is added to the instant coffee results in a slight foaming on the surface). The gasified extract is sprayed onto a moving freezing belt and, once completely solid, passes through mill-ing and classification stages. Granules within the desired size range are loaded into the freeze dryer where sublima-tion occurs. Once dried, they are then discharged for packing.

SPX has a proven track record in provid-ing turnkey instant coffee plants, which are designed for optimized energy con-sumption, higher yield and premium quality end-product. A programme of continued technology development and innovation has led to the unique solu-tions described above which offer better aroma recovery and higher yields than conventional systems while producing premium, aroma-rich instant coffee results. Indeed, innovative SPX instant coffee processing technology modern-izes conventional production tech-niques, which were developed during the 1980s and early 1990s.

Overall, SPX technology and coffee processing equipment provides instant coffee producers the potential for:

• Increased aroma recovery and better sensory end-product

• Increased production and end-prod-uct quality flexibility

• High yield performance

• A premium aroma-rich instant coffee end-product

• Reduced off-flavors within the instant coffee extract

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Advantages of the SPX high yield solutionSPX’s instant coffee processing plants are customized to meet specific end-product requirements and offer a range of benefits and flexibility throughout the processing line.

• Steam stripping of aromas prior to water extraction recovers the best and most desirable aromas from the roast and ground coffee.

• The short and wide percolator design enables the use of more finely ground coffee particles, which maximizes the aroma extraction and enables a higher flow rate to improve the extraction efficiency. This results in improved cof-fee extract quality and significantly higher yield from the quantity of green coffee beans used – which improves the process profitability and has the potential to save manufacturers several millions of dollars per year in green coffee bean procurement, depending on the size and capacity of the plant.

• The flow direction within the percolators is from bottom to top which sig-nificantly reduces the risk of any blockages.

• The roast and ground coffee is moistened inside the percolator to ensure aromas are not lost.

• For high quality extract, the system uses a dual-dual extraction mode, which ensures primary aromas are gently extracted and preserved.

• Flash separation for off-flavor removal is carried out in a vacuum vessel for higher process efficiency.

• The mixing of the aroma and coffee concentrate is carried out in-line which provides more uniform results compared with tank mixing.

• SPX offers a choice of continuous belt vacuum freeze dryers and tray vac-uum freeze dryers. Continuous belt freeze drying is ideal for smaller end-product capacity and offers advantages over tray freeze drying in terms of lower initial investment and lower operational costs. Improved efficiency is also gained with no requirement to handle and transport trays or to clean, wash and cool them after use. It has a capacity range of 100 kg/h – 250 kg/h.

• SPX continuous vacuum tray dryers offer a capacity range of 250 kg/h – 1,000 kg/h or higher.

• All SPX coffee plants are designed to meet specific customer requirements with respect to capacity, plant configuration and plant layout. SPX instant coffee plants further offer a fully automated solution with end-product flexibility.

Figure 2: SPX e&e Coffee percolators