Processing instant coffee is a process that is far more unfamiliar to people who used to use filter coffee. The article also helps people understand that the use of instant coffee is not only an advance of processing technology but also many other things, especially the enjoyment of a drink product that ensures food safety and hygiene. highest product.
Roasted green coffee beans are then ground to make coffee powder or processed into instant coffee.
The process for producing instant coffee from roasted coffee powder is as follows:
The extraction process aims to collect dissolved substances from roasted coffee powder into water. Use hot water at 80 – 90 ° C to extract. Do not use water with higher temperatures, as this will extract both substances that are not good for the product.
Instant coffee powder needs to be large in size and is extracted several times to limit the amount of fine powder that dissolves deeply into the water during extraction.
Intermittent extraction device is a tower containing a temperature-insulated coffee powder. Hot water is pumped from the bottom of the tower, through the column of roasted coffee powder in the tower. Here extraction of dissolved substances occurs. The coffee solution is collected at the top of the tower.
Must replace the coffee powder in the tower so that the extract when passing through the tower containing coffee powder will have increasing amount of solute. To avoid wetting of coffee powder, it is recommended to moisten the coffee powder with saturated steam before pumping water into the extract. The concentration of extracted coffee solution can reach 20 – 22%.
The concentration of coffee extract after extraction is 20 – 22%, which cannot be dried. Therefore, concentrated extract extract must be conducted to a concentration of 30-33% to facilitate the drying process.
The concentration method used is vacuum vacuum method:
The coffee solution is pumped into the heating device. Here the water receives heat and evaporates. The vacuum created by the barometer absorbs water vapor and condenses at the condenser. The process lasts until the satisfactory concentration of the solution stops.
Drying to make concentrated coffee extract into a dry powder for convenient storage and use.
The drying method used is the spray drying method:
The concentrated coffee solution is pumped into the top of cyclo. There is a small perforated disc, which has a great rotation speed, making the coffee solution into cyclo in the form of fog. Hot and dry air is blown into cyclo which dries the mist coffee into a powder. Instant coffee powder was collected at the bottom of cyclo.
After drying, we get instant coffee powder with moisture of 1-2%, dark brown color.
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If raw coffee powder is left for processing, the aroma of coffee will be greatly lost, especially during spray drying. Therefore, people recover the aroma of ground coffee before extracting and then adding back to instant coffee powder.
The desorption process is carried out in the vertical tower and the adsorbent is inert gas (N2). Powdered coffee is heated in the tower to release aromatic substances. Then pump inert heated gas to a certain temperature (95 ° C) from the bottom of the tower.
At the top of the tower, there is a suction fan that draws the gas mixture out of the tower, and creates low pressure to facilitate the adsorption process. We obtained a mixture of N2 gas and aromatic substances.
Instant coffee powder after drying has 1-2% moisture and very porous so it is easy to adsorb. Adsorption process is also conducted in the vertical tower. The inlet gas mixture must be cooled (temperature is usually 8 – 9 ° C), when going through the instant coffee powder will adsorb the aromatic substances in the gas mixture, we obtain instant coffee powder finished products .
Ho Van Toai (giacaphe.com)