IMPROVEMENTS IN A PROCESS FOR TREATING ROASTED COFFEE AND IN A PLANT FOR CARRYING OUT THE PROCESS

Abstract: Improvements in a process for treating roasted coffee and in a plant for carrying out the process, where the coffee is delivered in a seasoning container (4) wherein pressurized CO₂ or N₂ is blown in order to remove the most of the air therefrom, the O₂ is kept at controlled percentage and the coffee temperature is kept between 30°C and 50°C, thanks to a source (37) of fluid at about from 30°C to 50°C which is circulated in an interspace (28) around the seasoning container (4), through a time period comprised between ten and four days.

Description: By the European Patent 0 092 803 the Applicant disclosed a process for treating roasted coffee and a plant for carrying out the same process. The disclosed process comprises two steps. A first one in which the roasted coffee is delivered into one or more air-­ tight seasoning containers where a stream of CO₂ or of N₂ is blown in, in order to remove most of the air therefrom and to keep the O₂ percentage between 0,2% and 1%; the internal gas pressure in the seasoning container or containers is kept between 1 and 1,8 Atm; the roasted coffee stands in the seasoning container or containers through up to about twentyone days in a controlled O₂ ambient. A second step in which the coffee seasoned during the first step is passed in one or more stabilization containers where the coffee stands in a humidified air stream through a few hours. The plant comprises one or more air-tight seasoning containers whereto the roasted coffee is delivered; controlled inlet means for the gas coming in and from the seasoning container or containers; means for controlling the pressure in the seasoning container or containers; a pressurized CO₂ source or a pressurized N₂ source that is connected through the above inlet means with the interior of the seasoning container or containers; means that allow the roasted coffee to come out after the stationing in the seasoning container or containers; means that allow the seasoned coffee to pass into a centrifugal separator to separate coffee and air; a valve for allowing the coffee to pass into a distributor and then into one or more stabilization containers. A drawback in the process and in the plant as disclosed by the European Patent 0 092 803 is the coffee long stationing in the seasoning container or containers. The about twentyone days through which the coffee and the plant are engaged involve the use of a very capable plant for treating at the same time large quantities of coffee. The improvements according to the invented process and plant obviate the above described drawback. In order to get the following specification and claims easier, it is assumed that the process is carried out in one seasoning container only, instead of one or more seasoning containers. The inventor found that by performing the known process in a seasoning container in which the coffee is kept in a determined gap of temperatures higher than room temperature with maximum O₂ of 2% the process duration is shortened and the roasted coffee quality is even the best. Generally, an expert could expect that temperatures higher than room temperature should accelerate a great part of the physical and chemical changes in the roasted coffee. However what could not be known was the gap of temperatures higher than the room temperature within which the coffee could be treated so as to obtain, on one hand, a valuable reduction of the process duration and, on the other hand, still a best quality product. The invented process comprises, as it is known, a first step divided into two stages, in which coffee is seasoned in an air-tight seasoning container, and a second step in which the seasoned coffee is stabilized in stabilization containers that are opened to a flow of air and during the first stage, said roasted coffee being delivered into the seasoning container, then pressurized CO₂ or N₂ being delivered into the seasoning container for removing most of the air from the interior of the container. During the second stage the gas pressure in the interior of the seasoning container being got immediately to at least 0,4 Atm and then being able to be raised and kept at up to 1,8 Atm, characterized in that the O₂ percentage in the seasoning container is kept between 0,2% and 2% and that during the first step of the process the roasted coffee in the seasoning container is kept at a desired temperature between 30°C and 50°C through a time period of between ten to four days, of ten days if the temperature of the coffee is 30°C or of a lower number of days inversely proportional to the temperature of the coffee, so of four days if the temperature of the coffee is 50°C. Preferably the roasted coffee is kept in the seasoning container at a temperature of 40°C through about seven days. The plant according to the invention comprises, as it is known, means for delivering roasted coffee into a seasoning container, a seasoning container, a pressurized CO₂ and or N₂ source that is connected with the interior of the seasoning container, a controlled valve for allowing the air to go out of said container as the coffee and CO₂ and/or N₂ come in; valves for controlling the gas pressure in said container, means for controlling the O₂ percentage in said container, a valve for making the seasoned roasted coffee to fall on a conveyor that moves said coffee into a separator that separes the air from the coffee, an apparatus that moves the coffee into a distributor and therefrom into stabilization containers that are opened for a flow of humidified air and is characterized in that it comprises means adapted to lead the coffee temperature to the desired value in the seasoning container, according to the process, and to keep the coffee in the container at such a temperature through a desired time period, according to the process. Particularly the plant comprises: a warm fluid source under controlled temperature so as to keep the fluid at a value adapted to keep the coffee in said container at a desired value of temperature, a liner around the seasoning container in order to create an interspace between the liner internal wall and the container external wall; controlled means for supplying and circulating a convenient quantity of said warm fluid into the interspace and for allowing said fluid to come out therefrom; means for taking the temperature of said fluid in the interspace and the one of the coffee into the seasoning container. Alternatively the plant comprises a duct that is wound up as a coil on the external surface of the seasoning container, means for supplying and circulating a convenient quantity of said warm fluid into the above duct; means for taking the temperature of said fluid in said duct and of the coffee in the seasoning container. It will be realized that the warm fluid could be a liquid one, such as water, or a gas, such as air, and that the controlling of the warm fluid temperature, as supplied from such a fluid source shall take into account that the roasted coffee may be delivered into the seasoning container a little after the roasting completion, the coffee being at high temperature, or much after the roasting completion, the coffee being at room temperature or a little higher than room temperature. The temperature gap in the invented process, from 30°C to 50°C, was determined by the following facts as a result of researches and tests: the 30°C lower value is the one causing a reduction of the process duration yet advantageous and valuable with respect to the duration of the known process, viz. a reduction upto ten days with respect to the duration which may arrive up to twenty one days in the known process; it is obvious that said lower value can be reduced evenmore, but when comparing the advantages to the plant and process costs, they would be very little. The 50°C higher value, is the one not to be overcome in order to avoid a too much rapid gas evolving from the roasted coffee beans which could cause a non-controlled loss of the coffee flavours and then a bad product. The invented process and plant will be described in detail in the following, with reference to the example as illustrated in the attached drawing having a sole figure. The attached drawing is took up from the European Patent 0 092 803. In the attached drawing only one seasoning container 4 is shown; in the following the operation of the parts that are equal to the ones according to the above European Patent drawing, is not described: only a list of said equal parts is supplied herebelow: 1 conveyor for freshly roasted coffee; 2 hopper for freshly roasted coffee; 3 first pneumatic apparatus for delivering coffee (in which P is a pump); 4 seasoning container; 5, 6, 7, 10, 11, 16, 26 valves; 8 air outlet duct; 9 air filter; 12 O₂ percentage automatic analizer; 13 pressure gauge; 14 rapid gas exhausting valve; 15 acoustic alarm device for internal high pressure; 17 vibratory duct for seasoned coffee; 18 hopper; 19 second pneumatic apparatus for delivering coffee (in which P′ is a pump); 20 centrifugal dust separator; 21 rotating value for coffee passing through; 22 rotating coffee distributor; 23 distribution ducts; 24 stabilization containers; 25 air duct. The caracterizing parts of the invented plant are illustrated herebelow. A liner 27 is provided all around the seasoning container 4 and is spaced from it so as to form a closed interspace 28. The interspace 28 is connected upwards with the external air through the duct 29 and downwards, through the duct 31, with the warm air generator 30. A variable-displacement fan 32 positioned along the duct 31, blows warm air into the interspace 28. A valve 33 allows the controlling of the air quantity going out from the duct 29. Thermometers 34 indicate the air temperature in the interspace 28 and thermometers 35 indicate the coffee temperatures in the seasoning container 4. Thermostats 36 are adapted to control coffee temperature in the seasoning container 4 by driving the operation of the warm air generator 30. The source of pressurized CO₂ is referred to by 37. Since it was choosed to carry out a process by keeping the coffee in the container 4 at a temperature of 45°C, it will be processed as follows. When a lot of coffee having a temperature of about 30°C begins to enter the seasoning container 4 by means of the pneumatic apparatus 3, the warm air generator is driven so as to produce warm air at a temperature conveniently higher than 45°C. When the container 4 has been filled, one shall wait for the moment in which the coffee temperature arises from 30°C to 45°C so that the warm air generator will produce air at a temperature a little higher than 45°C in order to keep the coffee at 45°C and balance the heat losses along the duct 31 and through the external wall of the liner 27 even if suitably insulated. After 5,5 days the coffee has been delivered to the conditioning container, the coffee is transferred into the stabilization containers 24 and the conditioning container receives another lot of roasted coffee. Alternatively, after 5,5 days the coffee has been delivered to the conditioning container, a room temperature air stream is blown in order to adjust to the room temperature the coffee temperature into said container and then to transfer the coffee into the stabilization containers 24. Further alternatively, after 5,5 days the coffee has been delivered to the conditioning container, the coffee is removed from said container and its temperature is reduced to room temperature during its transferring into the stabilization container 24. Such a temperature reduction is reached through any known means, for instance: by ventilating the coffee, naturally or by means of a fan, while moving along the vibratory duct 17, or by blowing air at room temperature into the second pneumatic apparatus 19. Finally, the duct 29 instead of liberating outwards the warm air circulated into the interspace 28, takes back said air into the duct 31 section that is comprised between the generator 30 and the fan 32, in order to carry out a convenient energy regeneration.

Claims: 1. A process for treating roasted coffee, comprising a first step, divided in two stages, in which coffee is seasoned in an air-tight seasoning container (4), and a second step in which the seasoned coffee is stabilized in stabilization containers (24) that are opened to a flow of air, during the first stage first roasted coffee being delivered into the seasoning container (4), then pressurized CO₂ or N₂ being delivered into the seasoning container (4) for removing most of the air from the interior of the container (4), during the second stage the gas pressure in the interior of the seasoning container (4) being got immediately to at least 0,4 Atm and then being able to be raised and kept at up to 1,8 Atm, characterized in that the O₂ percentage in the seasoning container (4) is kept between 0,2% and 2% and that during the first step of the process the roasted coffee in the seasoning container (4) is kept at a desired temperature between 30°C and 50°C through a time period of between ten to four days, of ten days if the temperature of the coffee is 30°C or of a lower number of days inversely proportional to the temperature of the coffee, so of four days if the temperature of the coffee is 50°C. 2. A process for treating roasted coffee according to claim 1, characterized in that the roasted coffee is kept in the seasoning container (4) at a temperature of 40°C through about seven days. 3. A plant for carrying out the process according to claims 1, 2 comprising means for delivering roasted coffee into a seasoning container (4), a seasoning container (4), a pressurized CO₂ and/or N₂ source (37) that is connected with the interior of the seasoning container (4), control means for allowing the air to come out from said container (4) as the coffee and CO₂ and/or N₂ come in; valves for controlling gas pressure in said container (4), means for controlling O₂ percentage in the above container (4), a valve (16) for making the seasoned roasted coffee to fall on a conveyor (17) that moves said coffee into a separator (20) that separes air from coffee, an apparatus (21) that moves the coffee into a distributor (22) and therefrom into stabilization containers (24) that are opened for a flow of humidified air and is characterized in that it comprises means (30-31-28) adapted to lead the coffee temperature to the desired value into the seasoning container (4) according to the process and to keep the coffee in the container (4) at such a temperature through the desired time period, according to the process. 4. A plant according to claim 3, characterized in that it comprises a warm fluid source (30) under controlled temperature so as to keep the fluid at a value adapted to keep the coffee in said container (4) at a desired value of temperature, a liner (27) around the seasoning container (4) in order to create an interspace (28) between the liner internal wall and the container external wall, controlled means for supplying and circulating a convenient quantity of said warm fluid into the interspace (28) and for allowing said fluid to come out therefrom; means for taking the temperature of said fluid in the interspace (28) and the coffee temperature in the seasoning container (4). 5. A plant according to claim 3, characterized in that it comprises a warm fluid source (30) under controlled temperature so as to keep the fluid at a value adapted to keep the coffee in that above container (4) at a desired value of temperature, a duct wound as a coil on the external surface of the seasoning container (4), means for delivering and circulating a convenient quantity of said warm fluid into the above duct, means for taking the temperature of said fluid in said duct and the coffee temperature in the seasoning container (4).

Inventors: ILLY, ERNESTO
Applicants: ILLYCAFFE S.P.A.
Application year: 1986
Main classification: A23F5
IPC codes: A23F5