Food or edible material: processes – compositions – and products – Involving ion exchange – sequestering or chelating material
Reexamination Certificate
2000-01-24
2002-05-14
Pratt, Helen (Department: 1761)
Food or edible material: processes, compositions, and products
Involving ion exchange, sequestering or chelating material
C426S002000, C426S074000, C426S590000, C426S599000
Reexamination Certificate
active
06387425
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a method for producing a low potassium juice with improved taste and more particularly to a method for producing a juice with improved taste by decreasing the concentration of potassium in the juice and adding a calcium compound thereto. Further, the present invention relates to a juice suitable for patients suffering from kidney failure who are allowed to take up limited amounts of potassium and to whom administration of calcium carbonate is necessary.
BACKGROUND OF THE INVENTION
In cells of animals inclusive of humans, potassium mainly exists in an intracellular liquid and in a pair with sodium which exists mainly in an extracellular liquid and plays an important role in maintaining the homeostasis of a living organism as one of major factor in the acid base equilibrium. However, since patients suffering from kidney failure have decreased functions of excreting potassium and of maintaining blood ion balance so that they tend to be suffered from hyperkalemia, hyperphosphatemia, or hypocalcemia. An extreme increase in serum potassium level may cause the stop of the heart function and, in the worst cases, fatal situation.
Therefore, patients with kidney failure are subjected to strict restriction on the uptake of potassium and, in particular, they cannot freely take fruit or vegetables containing potassium in large amounts. As described above, patients with kidney failure tend to be suffered from hyperphosphatemia or hypocalcemia, and hence administration of calcium carbonate to such patients is necessary. Further, in the case of those patients who are subjected to the restriction on the uptake of fruit and vegetables, there arises a new problem that the contents of meal are unbalanced and it is difficult to maintain a nutritional balance.
Treatment of juice with ion exchange resins itself is a technology which has been known for a long time. J. Sci. Food Agric. (1966), 17(11), 488-90 reports the use of cation and anion exchange resins in preventing the precipitation of algallol and adjustment of the acidity of a grape juice. Also, it has been reported a trial to adjust potassium ion in juices using the ion exchange resins (Japanese Patent Application Laid-open No. Sho 61-209573, Brazilian Patent Application Laid-open No. 9704147, European Patent Application Laid-open No. 0339540).
However, foods adjusted to decrease the amount of potassium ion with ion exchange resins by the prior art have not always been satisfactory in respect of health care purpose, taste, texture, nutritional balance, etc. In the technology described in Japanese Patent Application Laid-open No. Sho 61-209573, since a decrease in the potassium content results in a considerable deterioration in the taste of the juice, the amount of depotassification is restricted to 90% or less of the amount of potassium contained in the raw material juice. That is, the taste is maintained by allowing about 10% of potassium to remain. Further reduction in the content of potassium is not conducted.
According to the guideline used in Japan, patients under maintenance blood dialysis who receives dialysis 3 times a week are subjected to a strict restriction on the uptake of potassium to 1.5 g/day. In this case, if the amount of potassium in juice of fruit or of vegetable is reduced until it is suitable for drinking by patients with kidney failure, the acidity increases excessively and the taste is extremely aggravated so that a drink having a taste suitable as juice is not obtained.
Brazilian Patent Application Laid-open No. 9704147 and European Patent Application Laid-open No. 0339540 disclose methods for producing depotassified juice containing water-soluble calcium ions by using calcium type cation exchange resin in order to improve the degree of deterioration of the taste as described above. Brazilian Patent Application Laid-open No. 9704147 discloses the technology of exchanging potassium ions and sodium ions in juice with calcium ions using calcium type cation exchange resin.
However, the calcium type cation exchange resin is limited in the content of water-soluble calcium salt necessary for the adjustment so that exchange of a large amount of calcium ions is unrealistic and it is only possible to provide juice which contains a trace amount of calcium ions in the range where they are water-soluble as contained in beverages.
Since use of the calcium type cation exchange resins is unrealistic, European Patent Application Laid-open No. 0339540 discloses a method for producing low potassium juice using novel calcium type cation exchange resin. That is, it discloses a method for producing calcium containing juice using calcium type cation exchange resin composed of polystyrene resin having sulfon groups, crosslinked to 80% with divinylbenzene.
However, also in this case, there are technical barriers, that is the amount of potassium ions removed and volume of exchange by the calcium type cation exchange resin. Therefore, the prior art remains to provide juice still containing potassium ion in an amount of about 30% of the total amount of potassium ion contained before the treatment.
Moreover, nowadays when ion exchange technology has been improved greatly, a method for the decationation of juice by means of ion exchange membranes has also been used widely. However, juice, which has a high solid content, causes clogging of the membrane, so that a reduction in the amount of ion is limited to about one fifth of the cations contained in raw material juice.
As stated above, in the prior art, it has been known to provide juice by removal of potassium ions using cation exchange resin and optional addition of calcium by use of calcium type cation exchange resin. However, there has been a limitation in technology to remove a sufficient amount of potassium while retaining taste and exchange a large amount of calcium ions by use of calcium type cation exchange resin.
It is needless to say that taste is one of the important elements of food. Foods from which merely potassium has been removed are not satisfactory to patients suffering from chronic kidney failure who are compelled to be subjected to dietary control for a long period of time. This is a serious problem. However, scientific clarification of sense of taste of humans has not been made sufficiently yet and in actualities, new foods and new tastes have been developed by at random screening and tremendous efforts by food technicians.
The problem that treatment with cation exchange resin in order to decrease the potassium content results in a loss of vitamins contained in raw material juice, in particular vitamin C, in a considerable amount has been overlooked. One object of juice beverages from the nutritional viewpoint is to supplement vitamin C. In addition, vitamin C, which gives unique taste, is important for the taste of juice. This problem does not have to be neglected.
SUMMARY OF THE INVENTION
An object of the present invention is to solve the problems associated with the prior art as described above. More particularly, an object of the present invention is to provide a juice which not only contains a reduced amount of potassium but also has improved taste and nutritional balance so that it can be taken with good taste for patients who suffer from malfunction of kidney such as kidney failure. In addition it is intended for the therapy of patients with kidney failure, i.e., control of blood potassium ion as well as improvement and prevention of hypocalcemia and hyperphosphatemia with calcium carbonate.
As a result of intensive study and research in various fields with a view to achieving the above object, it has been found that the addition of a suitable amount of a calcium compound selected from calcium carbonate and calcium hydroxide in the form of a solid to fruit juice or vegetable juice, whose acidity has been increased excessively owing to reduction of the potassium content with the use of a cation exchange resin, results in neutralization of acidity and improvement in taste. Accordingly, there can be produced a wid
Goto Takushi
Katamune Koji
Kinoshita Toshio
Kinoshita Yuko
Takizawa Toshio
Frishauf, Holtz Goodman, Langer & Chick, P.C.
Meiji Seika Kaisha Ltd.
Pratt Helen
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