Drug – bio-affecting and body treating compositions – Plant material or plant extract of undetermined constitution... – Containing or obtained from leguminosae
Reexamination Certificate
1999-09-17
2002-08-27
Lilling, Herbert J. (Department: 1651)
Drug, bio-affecting and body treating compositions
Plant material or plant extract of undetermined constitution...
Containing or obtained from leguminosae
C252S398000, C252S407000, C424S727000, C424S750000, C426S048000, C426S049000, C426S069000, C426S072000, C426S545000, C426S585000, C426S590000, C426S598000, C426S601000, C426S615000, C514S027000, C514S045000, C514S047000, C514S048000, C514S450000, C530S370000, C530S378000
Reexamination Certificate
active
06440469
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to a method of purifying plant proteins for use in nutritional products that have reduced levels of phytoestrogens, manganese and nucleic acids. More specifically, this invention is directed to a method of using ion exchange technology to remove phytoestrogens, manganese, nucleotides, nucleosides and RNA from plant proteins. This invention is also directed to the plant protein product resulting from the inventive process and to nutritional products that use the plant protein product as a source of amino nitrogen.
BACKGROUND OF THE INVENTION
Phytoestrogens or plant estrogens occur in a variety of plants, including vegetable protein materials such as those derived from soybeans. Phytoestrogens are defined as plant substances that are structurally and functionally similar to the gonadal steroid 17 &bgr;-estradiol or that produce estrogenic effects. There are three main groups of nonsteroidial dietary estrogens which are 1) the isoflavones, 2) the coumestans and 3) the mycoestrogens (fungal). The structural similarity between these substances and the endogenous mammalian estrogens have been studied. A review of phytoestrogens and their effects in mammals is reported by Kaldas and Hughes in an article entitled, “Reproductive and General Metabolic Effects of Phytoestrogens in Mammals”,
Reproductive Toxicology,
Vol. 3, pp. 81-89, 1989. The teachings of this article are herein incorporated by reference. As used in this specification and the appended claims, the term “isoflavones” is equivalent to the term “phytoestrogens” as that term is defined in the Kaldas et al. article. Representative of the isoflavones that are reduced in plant proteins in accordance with the present invention are daidzein, daidzin, genistein and genistin.
Flavonoids and isoflavones are produced by numerous leguminosoe and grasses, including many plants commonly consumed by man and livestock. Soy isoflavones include compounds such as daidzin, genistin, daidzein and genistein. A general structural formula for these compounds is:
Compound
R
R
1
daidzein
H
H
genistein
H
OH
daidzin
G
H
genistin
G
OH
wherein G = glucosyl
It has recently been recognized that isoflavones contained in vegetable proteins may have a detrimental impact upon the mammals that consume the vegetable protein, see Kaldas et al., supra. The concentration of isoflavones in plant protein isolates or concentrates such as soy protein isolates, can be as high as 3,000 &mgr;g/g of protein. Isoflavones also provide the bitter or “beany” taste to vegetable proteins, (see Ewan et al. infra) may reduce the bioavailability of essential minerals and may influence the nutritional value of proteins (see Kaldas et al., supra). The consumption of isoflavones by man and livestock has also been connected with compromised reproductive systems in mammals. There is some concern that consumption of current soy based infant formulas that contain soy isoflavones may have an undesired physiological impact on the developing neuro-endocrine system of the infant. This concern is based in part, on evidence that soy-based animal feed may cause fertility problems in cheetahs. Setchell et al., 1987: “Gastroenterology” 93:225-33.
Further, the presence of high levels of manganese in body tissues has been suspected in the development of criminal behavior. See Gottschalk et al., “Abnormalities in Hair Trace Elements as Indicators of Aberrant Behavior”,
Compr Psychiatry
1991; 32:229-237, and
Scientific American,
March, 1995 pp. 104-105. Furthermore, there have also been reports that learning disabilities in children may be associated with increased levels of manganese in hair as reported by Collipp et al., in an article entitled, “Manganese in Infant Formula and Learning Disabilities”,
Ann. Nutritional Metals,
27:488-494, 1983. Typical plant protein isolates contain up to 1000 &mgr;g of manganese per gram of protein. Thus, there is a need for improved processes that economically and on a commercial scale, provide for the reduction of isoflavone and manganese content in plant protein.
The use of nucleotides and nucleosides (or nucleotide equivalents as defined below) in nutritional formulas has received much attention in the last few years. It has been suggested that certain levels and ratios of the various nucleic acids can have a positive impact on the mammalian immune system and even prevent certain maladies such as diarrhea. The problem with using plant protein in such nutritional formulas is that the plant protein contains typically very high, inherent level of nucleic acids that may not be in the correct form (i.e., RNA) and at the correct ratios. Further, the high level of variation in the nucleic acid content causes problems in commercial manufacture. Typical plant protein isolates contain up to about 15 mg of nucleotide equivalents per gram of protein. Thus, the nutritional industry desires a source of plant protein that has substantially reduced levels of inherent nucleic acids. One additional benefit to the process of this invention is that, not only can the isoflavones and manganese be removed by the ion exchange column but also a substantial portion of the inherent nucleic acids.
Ion-exchange technology has been known for a great number of years. Ion-exchange resins are typically synthetic, insoluble, cross-linked polymers carrying acidic or basic side groups. They have high exchange capacities and can be used for an almost unlimited number of reactions. Ion-exchange resins are used in water-treatment, extraction, separation, analysis and catalysis.
Ion-exchange resins have an extended, open molecular framework that includes electrically charged ionic groups. A cation exchanger exchanges positive ions and therefore has negative ions built into its framework. An anion exchanger has positive ions in its framework. The ions of the lattice are called the fixed ions; the smaller ions of opposite charge that can change places with ions in the solution are called counterions.
Common problems encountered with ion exchange processes conducted on proteins include poor protein recovery (i.e., protein adhered to the resin) and inability of the protein slurry to pass through the resin bed resulting in a high pressure drop across the resin bed. The process which is disclosed herein fulfills the need in the nutritional industry for a source of plant protein that has highly reduced levels of isoflavones, manganese and nucleotides is economical, provides good protein recovery and can be used on a commercial scale.
U.S. Pat. No. 5,352,384 to Shen discloses a process to produce an isoflavone enriched vegetable protein fiber. This patent discloses the use of a glucosidase to convert the glucone isoflavones (i.e., daidzen) in a protein slurry to the aglucone isoflavones. The fiber fraction is then recovered from the slurry by centrifugation to provide an aglucone enriched fiber.
An article by Ewan et al. in the
Journal of Food Science,
Vol. 57, No. 2, 1992 entitled: “Isoflavone Aglucones and Volatile Organic Compounds in Soybeans; Effects of Soaking Treatments”, discloses the beneficial effects of soaking soybeans in mildly alkaline NaHCO
3
solutions at elevated temperatures, for manufacturing soymilk with improved flavor. This publication does not suggest or disclose the use of an ion-exchange resin to remove isoflavones, manganese and nucleic acids from plant protein.
In an article published in volume 47 (1982) of the Journal of Food Science, pp. 933-940, by J. How and C. Morr entitled “Removal of Phenolic Compounds from Soy Protein Extracts Using Activated Carbon”, they report subjecting soy protein extracts to activated carbon and ion exchange process treatments to remove phenolic compounds that have been reported as being responsible for adverse color and flavor characteristics of soy protein products. Protein extracts were subjected to a two stage, sequential ion exchange treatment prior to protein precipitation. The protein extract was pumped “down-flow” through a cation exchange column in the Na&plus
Anloague Paul S.
Chmura James N.
Daab-Krzykowski Andre
Garcia Diane M.
Johns Paul W.
Abbott Laboratories
Dixon I. Michael
Lilling Herbert J.
LandOfFree
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