Liquid purification or separation – Processes – Chemical treatment
Reexamination Certificate
2000-05-02
2003-09-09
Hoey, Betsey Morrison (Department: 1724)
Liquid purification or separation
Processes
Chemical treatment
C210S764000, C210S188000, C210S192000, C210S199000, C210S205000, C210S252000
Reexamination Certificate
active
06616849
ABSTRACT:
The present invention relates to a method of and system for continuously processing liquid material such as liquid foodstuff or liquid medicine using a supercritical or subcritical fluid. The “processing” hereby includes: inactivation of enzymes and spores in and sterilization of liquid foodstuffs, liquid medicines or the like; and deodorization of liquid foodstuffs. The present invention also relates to a liquid material produced by the method or system according to the present invention.
BACKGROUND OF THE INVENTION
There are various kinds of foodstuffs containing enzymes there days, in which sake, beer and juice are typical examples. In general, a process of producing sake includes: first step where fermented rice is compressed and filtered to obtain shinshu (green sake); second step where this obtained green sake is sterilized by heating and then stored; third step where plural lots of stored sakes are properly mixed to determine the sake quality and the alcohol content is adjusted to the standards; and fourth step where the thus adjusted sake is again sterilized by heating and then bottled or packed. As described above, sake undergoes the heat-treatment twice in the second and fourth steps in the manufacturing process to inactivate and kill bacteria therein, whereby the sake quality is prevented from deteriorating during market circulation. A problem here is that the fresh aroma of green sake is sharply reduced by the heat-treatments. Therefore, a non-heat-treated sake, or fresh sake, preserving the fresh taste and aroma, is in great demand. To meet the demand, the fresh sake is also circulated in the market by keeping it at low temperature. Such a non-heat-treated sake, however, contains enzymes such as &agr;-amylase and protease, which deteriorate the sake quality. The increased circulation cost due to the low temperature circulation is anther problem.
As for muddled fruit drinks such as orange juice, it is necessary to inactivate pectin esterase in order to maintain the muddled state of the drink. Since pectin esterase is stable to heat, a heat-treatment for inactivating this enzyme must be conducted at high-temperature (88-99° C., or 120° C.). The heat-treatment at such high temperature, however, deteriorates the relish of the drink.
Regarding the above-described problems, some of the inventors of the present application proposed a method of processing liquid foodstuff containing enzymes, as disclosed in Japanese Unexamined Patent Publication No. H07-170965, where the enzymes are inactivated by contacting carbon dioxide in a supercritical state. According to this method, the liquid foodstuff containing enzymes is contained in a processing chamber, which is then sealed, and supercritical fluid of carbon dioxide is supplied into the sealed processing chamber. The temperature and pressure inside the processing chamber are kept appropriately under preset conditions, and the supercritical fluid is supplied into the chamber through a filter whereby the fluid is formed into micro-particles having diameters of about a few hundreds of micrometers or less. Thus, the supercritical fluid of carbon dioxide effectively dissolves into the liquid foodstuffs. This method not only improves the inactivating efficiency, but also is highly safe since it is only carbon dioxide that contacts the liquid foodstuff. By this method, simultaneously, microorganisms such as bacteria, yeast fungus or mold can be killed.
Also, some of the inventors of the present application proposed a continuous processing system constructed so that the inactivating and sterilizing process is carried out more effectively and with less quality deterioration (Japanese Unexamined Patent Publication No H09-206044 or corresponding U.S. Pat. No. 5,704,276). With this continuous processing system, the liquid foodstuff is continuously supplied into a processing chamber from its bottom while maintaining the inside of the chamber at preset temperature and pressure. Carbon dioxide in a supercritical state is continuously supplied into the processing chamber through a mesh filter provided at the bottom of the chamber. In the upper part of the processing chamber is located a take-out port at a level a little lower than the level of the liquid foodstuff, from which the product (or processed liquid foodstuff) is taken out. In the processing chamber, the liquid foodstuff and micro-particles of the supercritical fluid flow upwards in parallel, contacting each other, whereby the enzymes are effectively inactivated. The processing chamber also has a drainage port for draining the supercritical fluid from the chamber. The supercritical fluid taken out from the drainage port is returned to a carbon dioxide source to be used again. Since this system can continuously process a liquid foodstuff, it is suitably used in a drink or food factory where a large amount of liquid foodstuff is to be processed.
With the above-described continuous processing system, the inactivation of enzymes in or sterilization of liquid materials is efficiently carried out. The practical use of this system, however, is difficult because of the cost problem as follows.
In the above continuous processing system, the temperature of the processing chamber must be kept at or above 31.1° C. in order to maintain the carbon dioxide in the supercritical state. Such a condition relating to temperature, however, is not preferable in view of efficient dissolution of carbon dioxide into the liquid foodstuff because carbon dioxide less dissolves into a liquid foodstuff as the temperature is higher. Hence, for obtaining an adequate inactivating and sterilizing effect, it is necessary to keep the liquid foodstuff and the supercritical fluid flowing in parallel for a considerably long time (from a few minute to a few tens of minutes, for example). Such a long processing time can only be realized by using a processing chamber of a large capacity. Also, a warming apparatus is necessary to the processing chamber to maintain the above-mentioned temperature. Another warming apparatus is necessary for moderately warming the liquid foodstuff in the course of transfer from a source to the processing chamber, because the reaction in the processing chamber is slow if the temperature of the liquid foodstuff supplied into the processing chamber is low. Thus, the continuous processing system becomes inevitably large and requires a large installation space, and the construction cost should be high.
Another problem lies with respect to the temperature of the processing chamber. Though, in the above-described system, the temperature in the processing chamber is considerably lower than the temperature for inactivating enzymes by heat, the temperature; is higher than a normal ambient temperature. It is possible therefore that the quality of the liquid foodstuff is deteriorated while the liquid foodstuff is kept at such a temperature for the process contains enzymes of high activity, and the enzymes badly affect the quality of the juice in the processing chamber before they are completely inactivated.
For solving the above-described problems, one object of the present invention is to propose a method of and system for continuously processing liquid materials with a small-sized processing chamber (or chambers) and a minimum number of warming apparatuses. The present invention also proposes a liquid material processed by such method or system.
SUMMARY OF THE INVENTION
In the above-described continuous processing system, the process of dissolving carbon dioxide into the liquid material and the process of changing the carbon dioxide into a supercritical state and maintaining the state are carried out simultaneously in the processing chamber. In contrast to that in the method or system according to the present invention the two processes are carried out separately in time and space.
Thus, in a method of continuously processing a liquid material such as liquid foodstuff with a supercritical or subcritical fluid, the process according to the present invention includes:
a) a dissolving stage where a liquef
Miyake Masaki
Osajima Yutaka
Shimoda Mitsuya
Takada Michinosuke
Hoey Betsey Morrison
Shimadzu Corporation
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