Chemistry: natural resins or derivatives; peptides or proteins; – Proteins – i.e. – more than 100 amino acid residues – Plant proteins – e.g. – derived from legumes – algae or...
Reexamination Certificate
1998-10-12
2001-05-08
Riley, Jezia (Department: 1656)
Chemistry: natural resins or derivatives; peptides or proteins;
Proteins, i.e., more than 100 amino acid residues
Plant proteins, e.g., derived from legumes, algae or...
C426S472000, C426S044000, C426S046000, C514S002600, C424S439000
Reexamination Certificate
active
06228993
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to a process for making an isoflavone concentrate product from soybeans. Isoflavones are a unique class of phytoestrogens—plant hormones—that naturally occur in soybeans.
It is anticipated that consumer demand for soy isoflavones will continue to grow. Scientists have demonstrated that isoflavones have the ability to inhibit cancer cell growth, and some researchers believe that isoflavones may contribute to soy's ability to lower blood-cholesterol levels.
The principal types of isoflavones found in soybeans are glucones (with sugars) and aglucones (without sugars). Glucones have the glucose molecule attached, and include genistin, daidzin and glycitin. Aglucones are isoflavones without the glucose molecule, and they include genistein, daidzein and glycitein.
The prior art teaches isolating genistin from hexane-extracted soybean flakes. Walter (“Genistin (an Isoflavone Glucoside) and Its Aglucone, Genistein, from Soybeans,”
J. of Am. Chem. Soc.,
63, 3273 (1941)) describes a method involving, among other steps, extracting the flakes with methanol, precipitating with acetone and recrystallizing with ethanol.
U.S. Pat. No. 5,141,746 (Fleury et al.) describes a method for preparing an impure extract of two specific isoflavones daidzin malonate and genistin malonate. Fleury describes a method involving, among other steps, mixing hexane-defatted ground soybeans with 80 percent (%) aqueous methanol, filtering and drying; adjusting pH multiple times with, among other chemicals, hydrochloric acid and sodium hydroxide, and extracting with an organic solvent, such as butanol.
U.S. Pat. No. 5,352,384 (Shen) describes making an aglucone enriched fiber. Shen describes solubilizing isoflavones from soy flour by, among other steps, forming a slurry with an extractant, such as sodium, potassium or calcium hydroxide, to adjust the pH to the proteins' isoelectric point of 6.7-9.7, and reacting the slurry with the enzyme beta-glucosidase.
The use of multiple acids/bases and organic solvents to extract isoflavones from soybeans makes it costly to commercially manufacture soy isoflavone products. The use of a number of materials to extract isoflavones, not only increases raw material, equipment and labor costs, but also creates significant safety and environmental concerns.
It is apparent that an efficient process for removing isoflavones from soybeans is needed. It also is apparent that a low-cost soy isoflavone concentrate (SIC) product is needed.
SUMMARY OF THE INVENTION
I discovered a novel process for manufacturing a novel SIC product. The isoflavone content by weight of the SIC product is 8 to 11 times that of soy flour, which typically has about 0.6% by weight isoflavones. More particularly, the SIC product contains at least 4% by weight isoflavones, 20-60% protein, with it typically being at least one-third protein, and a relatively low amount of fiber, with it typically being less than 5% fiber.
My process does not use other chemicals, such as, acetone, hydrochloric acid or sodium hydroxide, to manufacture the SIC product from soy solubles. Soy solubles are recovered from alcohol-extracted hexane-defatted soybean flakes. These solubles, sometimes called soy “molasses”, are desolventized, such that they contain less than 0.5% alcohol, and typically are evaporated to 60% solids.
I learned that soy solubles, on average, contain 3.31 milligrams per gram (mg/g) genistin on a wet basis and have a total isoflavone content (i.e., daidzin, glycitin, genistin, mal-daidzin, mal-genistin, daidzein, glycitein, genistein and some unidentified isoflavones) of 8.96 mg/g on a wet basis as determined by high performance liquid chromatography (HPLC). I discovered that if the soy solubles are diluted with water to form a slurry and the undissolved solids are removed from the slurry to form a wet “cake”, the cake contains a significantly concentrated amount of isoflavones.
I further discovered that if the soy solubles, which have about 20 mg/g isoflavones on a dry basis, are diluted with water to a certain percent solids and the undissolved solids a separated from the diluted solubles with a certain type of centrifuge that the isoflavone content of the solubles can be concentrated by at least 2 times. It was surprising and unexpected to learn that a product with such a high isoflavone content could be produced from the soy solubles without adjusting the solubles' pH with bases or extracting the solubles with another solvent.
DETAILED DESCRIPTION OF THE INVENTION
The steps of the subject invention are: 1) dehulling whole soybeans; 2) flaking the dehulled soybeans; 3) extracting soybean oil from the flaked soybeans with hexane, a solvent; 4) desolventizing the defatted soybean flakes without high heating or toasting to produce “white” flakes; 5) extracting the white flakes with aqueous alcohol; 6) recovering solubles from the extraction; 7) desolventizing (removing alcohol) from the soy solubles; 8) diluting the soy solubles with water to form a slurry; 9) separating the undissolved solids from the slurry to form a cake and 10) drying the wet cake. The general procedure for steps 1 through 3 is well described in the prior art. E.g., “Extraction of Oil from Soybeans,”
J. Am. Oil Chem. Soc.,
58, 157 (1981) and “Solvent Extraction of Soybeans,”
J. Am. Oil Chem. Soc.,
55, 754 (1978).
The first step is the dehulling process in which the soybean hulls are removed from the whole soybeans. The soybeans are carefully cleaned prior to dehulling to remove foreign matter, so that product will not be contaminated by color bodies. Soybeans also are normally cracked into about 6 to 8 pieces prior to dehulling.
The hull typically accounts for about 8% of the weight of the whole soybean. The dehulled soybean is about 10% water, 40% protein, 20% fat, with the remainder mainly being carbohydrates, fiber and minerals.
The second step involves the flaking process. Soybeans are conditioned prior to flaking by adjusting moisture and temperature to make the bean pieces sufficiently plastic. The conditioned bean pieces are passed through flaking rolls to form flakes about 0.01 to 0.012 inches (in) thick.
In the third step, the soybean flakes are defatted by contacting them with hexane to remove the soybean oil. Soybean oil is used in margarine, shortening and other food and products, and is a good source of lecithin, which has many useful applications as an emulsifier.
A detailed description of the general procedure for steps 4 through 7 is found in U.S. Pat. Nos. 3,365,440 (Circle et al.) and 5,097,017 (Konwinski). These steps generally involve the alcohol process for manufacturing soy protein concentrate (SPC). SPC has been described in commerce as a product containing not less than 70% protein (N×6.25). See A. K. Smith and S. J. Circle, Editors, “Soybeans: Chemistry and Technology, Volume I, Proteins,” the AVI Publishing Co., 1973.
In step 4, the hexane-defatted soybean flakes are desolventized—hexane is removed—without toasting to produce white flakes. This is different than conventional soybean oil hexane processes where the flakes are toasted and used for animal feed. Instead of being further processed into SPC, the white flakes can be ground to make soy flour.
In step 5, the white flakes are extracted with 55-75%, typically 60%, by weight aqueous ethanol in a countercurrent (flake to solvent flow) extraction device—extractor. The alcohol to flake ratio is about 5 to 1.
The alcohol extraction removes carbohydrates, including oligosaccharides, from the white flakes which thereby increases the protein content of the material. A typical sample of soy molasses from the SPC alcohol process was found to contain 7.80, 128.50, 19.45 and 86.79 mg/g glucose, sucrose, raffinose and stachyose, respectively, on a wet basis. Soy molasses also typically contains 7-8% protein and 10% ash on a wet basis.
The description of steps 8 through 10 is summarized in the previous section. In the preferred embodiment of this invention, the diluting, separating, pasteurizing and dr
Central Soya Company, Inc.
Fueling Michael L.
Riley Jezia
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