1. Field of the Invention
The invention relates generally to a gum-protein conjugate as an alternative to propylene glycol alginate [PGA], which both thickens and emulsifies for use in food emulsions, cosmetics and industrial applications.
2. Background
A gum that can both thicken and emulsify is rare in the market and currently only propylene glycol alginate (“PGA”) fits this definition. As noted below, the prior art discloses conjugating a non-viscous gum or blend of polysaccharides and a protein to produce an emulsifier. While such products can work in some emulsion applications, they still require a thickener to stabilize many emulsified products such as salad dressings, dips, soups and sauces to increase viscosity, and reduce oil and water movement. The following references describe these and similar products.
U.S. Pat. No. 5,591,473 entitled “Protein-Polysaccharide Complex Composition, Method and Preparation of Use” discloses a protein-polysaccharide complex of a substantially water insoluble protein, such as prolamine, and a polysaccharide, such as guar gum or gum arabic or other complex plant exudate polysaccharides, where the polysaccharide comprises 90% to 99.5% by weight of the total complex.
U.S. Pat. No. 5,645,880 entitled “Protein-Polysaccharide Complex Composition and Method of Use” discloses a food preservative comprising a stabilizing acid and a protein-polysaccharide complex. The complex comprises a substantially water-insoluble protein, such as a prolamine, and a water-soluble polysaccharide, such as guar gum or gum arabic.
U.S. Pat. No. 6,106,828 entitled “Conjugation of Polypeptides” discloses a polypeptide conjugate used to reduce allergenicity of industrial products. The conjugate comprises a polymeric carrier molecule, such as carboxymethylcellulose, guar gum, alginic acid, etc., coupled to two or more polypeptide molecules, especially polypeptide molecules having enzymatic activity.
U.S. Pat. No. 6,956,119 entitled “Polysaccharide-Protein Conjugate” discloses a method for producing a polysaccharide-polypeptide conjugate by reacting at least one antigenic polypeptide with a partially oxidized polysaccharide carrier.
U.S. Pat. No. 7,601,381 entitled “Polysaccharide and Protein Conjugate, and Emulsifiers and Emulsions Containing It” describes an emulsifying agent composed of soybean protein and soybean polysaccharides.
U.S. Pat. No. 6,225,462 entitled “Conjugated Polysaccharide Fabric Detergent and Conditioning Products” discloses a laundry detergent product comprising a polysaccharide with a 1-4 linked glycan backbone structure conjugated to a protein which is an enzyme, antibody or antibody fragment.
U.S. Patent Application No. 2008/0241320 entitled “Protective Hydrocolloids for Active Ingredients” discloses both a composition comprising a rice endosperm protein partially conjugated with mono-, di-, or oligosaccharides and a fat-soluble active ingredient, as well as, an associated method for making the composition.
U.S. Patent Application No. 2009/0311407 entitled “Production of Protein-Polysaccharide Conjugates” describes a protein-polysaccharide conjugate created by reacting a polysaccharide containing a reducing sugar and a protein in an aqueous solution under specific temperature conditions. The solution comprises 10%-40% by weight polysaccharide and 1%-30% by weight of protein.
U.S. Patent Application No. 2008/0299281 entitled “Emulsifiers and Emulsions” describes a protein-polysaccharide conjugate derived from whey protein and a non-ionic polysaccharide that acts as an emulsifier. An associated process for making said emulsifier is also disclosed.
U.S. Patent Application No. 2010/0098827 entitled “Modified Protein-Based Low-Carbohydrate Food Ingredient and Process for Making Same” discloses a modified protein-carbohydrate conjugate that has a viscosity of at least 1.0 Pa-s at a shear rate of 50 s−1 at 25° C., and a creaming index of less than 25%, as well as, a process for producing the complex.
There are also published works discussing the conjugation of a polysaccharide with a protein.
The conjugation of sodium caseinate and gum arabic catalyzed by transglutaminase was published in J. Agric. Food Chem., 2006, 54 (19): 7305-7310. The extent of conjugation was monitored by size exclusion separation coupled with a multi-angle laser light scattering detector where the molecular masses of the conjugates increased from ˜50 kDa to 1600 kDa. This method of protein-polysaccharide conjugation offered noticeable advantages over previously used methods, and the conjugates exhibited unique functional properties.
The kinetics of formation and functional properties of conjugates prepared by dry-state incubation of beta-lactoglobulin/acacia gum electrostatic complexes was published in J. Agric. Food Chem., 2005 Nov. 16; 53 (23): 9089-9099. Complexes were formed at pH 4.2 upon dry-state incubation for up to 14 days at 60° C. and 79% RH. SDS-PAGE electrophoresis with silver staining confirmed the formation of β-lactoglobulin/acacia gum conjugates. The conjugates exhibited higher foam capacity than the incubated protein, as well as, lower equilibrium air/water surface tension.
Finally, a study entitled “Whey protein-maltodextrin conjugates as emulsifying agents: An alternative to gum arabic” was published in Food Hydrocolloids (2007), 21(4): 607-616. This study investigated the conjugates under both acidic and high electrolyte concentration conditions in systems containing medium-chain triglyceride oil or orange oil. Covalent coupling of protein to polysaccharide was achieved by dry-heat treatment of a protein and polysaccharide mixture for up to two hours. A whey protein-maltodextrin conjugate (WP-MD19) made from maltodextrin (Dextrose Equivalent=19) of intermediate mean molecular weight (8.7 kDa) was found to be capable of producing fine emulsion droplets (0.5 μm-1 μm) with either triglyceride oil or orange oil.
It is an aspect of the present invention to produce gum-protein conjugates capable of acting as both thickeners and emulsifiers. Conjugates are generally known in the art as substances that are formed when two compounds are chemically combined. Certain embodiments of the conjugation processes described herein uses guar gum in its milled, powdered form or as obtained from guar splits (as described below) as the viscous substrate and conjugates the guar gum with a protein that is either endogenous (originating from the guar seeds itself) or exogenous (of non-guar origin).
For example, a first embodiment of the present invention uses endogenous guar proteins as the conjugating proteins, which endogenous proteins are obtained from the guar seed itself. After dehusking and milling, the guar seed yields two fractions: the bran (ground germ and husk) and the endosperm. Guar gum is derived from the endosperm, while the guar bran contains the endogenous proteins used in the first embodiment of the present invention. Roughly, 100 kg of dried guar seeds yields 50 kg of endosperm or guar gum, and 50 kg of guar bran, which guar bran is composed of approximately 25 kg endogenous proteins and 25 kg husk and other insoluble materials. In this first embodiment, gum-protein conjugates that both thicken and emulsify comprise between 1% and 25% endogenous guar protein, which protein is obtained by dissolving the guar bran obtained after dehusking the guar seeds and which protein is unrefined and not further treated (i.e., “as is” basis), conjugated with milled, powdered guar gum.
One preferred method for producing such conjugates may be obtained by performing the following steps:
In addition, guar gum obtained from guar splits may be used instead of milled, powdered guar gum. Guar splits are created when the guar seed, which is dicotyledon in nature—meaning it is composed of two cotyledons attached at one end of the seed—splits into two during dehusking.
In one method, the following step may replace step ii) above:
One preferred process of producing such conjugates may include the following steps:
As with other embodiments, guar gum from guar splits may be used instead of powdered, milled guar gum so long as a similar procedure is followed as that discussed above (but, of course, replacing references to “guar bran protein” with the exogenous proteins of this embodiment).
Following these procedures, it is possible to obtain gum-protein conjugates having thickening and emulsifying properties, including, but not limited to, guar gum-guar bran protein conjugates and guar gum-exogenous protein conjugates. In one example, adjusting the pH of the guar gum/guar protein solution to between about 8.0 and about 12.0 was found to decrease conjugation time and make the conjugation process more cost effective. Indeed, in some instances, an acidic environment (i.e., pH of 2.0-3.5) resulted in unsuccessful conjugation. While it is generally known in the art that high pH values can decrease conjugation time, it was unexpected that a very basic solution could be used in the conjugation reaction described herein; as such environments can damage both proteins and guar gum.
The efficacy of the conjugates created via the exemplary conjugation processes described above has been confirmed via a model salad dressing emulsion test, wherein the gum conjugates of the present invention were added to a salad dressing and the resulting mixture was observed to determine, among other things, if separation occurred. To create the exemplary salad dressing used for observation, the following procedure was performed using the values set forth in Table 1.
First, water and high fructose corn syrup were weighed separately. Potassium sorbate was then added to the water and mixed until dissolved. Next, one of the gum conjugates of the present invention was added to the water/potassium sorbate mixture and mixed for 10 minutes. Salt was then added to the high fructose corn syrup and mixed for three minutes. Finally, the water/potassium sorbate/gum solution and the high fructose corn syrup/salt solution were mixed together for one minute, thereby forming the salad dressing used for observation and testing.
Test results (see
An attempt to conjugate guar gum and gelatin was unsuccessful. Given that gelatin is a fibrous structural protein and quite inflexible, whereas whey protein is globular and flexible, this suggests that, to a certain degree, proteins that are both globular and flexible help to give the conjugate a good emulsifying property.
Although the disclosure has been described and illustrated with a certain degree of particularity, it is understood that the disclosure has been made only by way of example, and that numerous changes in the condition and order of steps can be resorted to by those skilled in the art without departing from the spirit and scope of the disclosure.
This application claims priority to U.S. Provisional Patent Application No. 61/473,404, filed Apr. 8, 2011, which is incorporated herein in its entirety.
Number | Date | Country | |
---|---|---|---|
61473404 | Apr 2011 | US |