Food or edible material: processes – compositions – and products – Products per se – or processes of preparing or treating... – Protein – amino acid – or yeast containing
Reexamination Certificate
1998-12-24
2001-01-16
Pratt, Helen (Department: 1761)
Food or edible material: processes, compositions, and products
Products per se, or processes of preparing or treating...
Protein, amino acid, or yeast containing
C426S028000, C426S049000, C426S052000, C426S093000, C426S094000, C426S102000, C426S292000, C426S293000
Reexamination Certificate
active
06174559
ABSTRACT:
BACKGROUND
Egg wash is typically used as a baking gloss for enhancing the appearance of breads, pies, cakes and other baked goods. However, with the growing concern of Salmonella contamination of processing equipment and food, alternative compositions that provide good gloss finishes on edible substrates are desirable.
SUMMARY OF THE INVENTION
The present invention relates to methods of forming colloidal dispersions containing microparticles of gluten-derived proteins and peptides. The colloidal dispersions can be maintained as stable, homogeneous dispersions under storage conditions (e.g., ambient, cold or frozen) without microbial contamination. Alternatively, the colloidal dispersions can be dried and rehydrated prior to use.
Colloidal dispersions of the present invention, when cast onto a substrate, form a glossy coating when dried at ambient or elevated temperatures. The films can further serve as an adhesive for adhering particulate material (e.g., seeds, salts, spices, confections, fruit) onto the substrate. Suitable substrates include but are not limited to confections, cooked and dehydrated meats, dessert items, snack foods (e.g., pretzels, chips, tortillas), fried foods (e.g., french fries), candies (e.g., chocolates), fruit (e.g., apples), vegetables, cereals, baked goods, seeds, nuts, beans (e.g., coffee), pharmaceuticals (e.g., vitamins and tablets) and paper.
Edible coatings produced by the present method are clear films which are non-toxic since they are derived from gluten from wheat, corn, rye, barley, rice or sorghum. The colloidal dispersions of the present invention do not contain toxic organic solvents, thus, the residues of these undesirable elements are minimized or eliminated.
DETAILED DESCRIPTION OF THE INVENTION
The invention pertains to aqueous colloidal dispersions of gluten-derived proteins and peptides, which when coated onto a substrate will impart a glossy coating thereon. The invention further pertains to methods for making the aqueous gluten-derived colloidal dispersions, to methods for using the gluten-derived colloidal dispersions as a baking gloss, for example, and to edible coatings on various substrates, included foods, pharmaceuticals and paper. The invention further pertains to methods for adhering edible particulate material (e.g., seeds, spices, candies, nuts) onto the surface of a substrate using the colloidal dispersions described herein.
The term “colloidal dispersion” as used herein means a suspension of microparticles of gluten-derived proteins and peptides having a median volume diameter of about 10 microns or less in an aqueous medium. Preferably, the gluten-derived microparticles will be from about 4 to about 5 microns and should be essentially free of starch. The terms “stable” and “homogeneous” as used herein define colloidal dispersions in which substantially all the microparticles of gluten-derived proteins and peptides can remain uniformly dispersed within the aqueous medium for an indefinite period of time under storage conditions, without irreversible precipitation or agglomeration.
Gluten usefull in the methods of this invention is found in high concentrations in various grains, such as wheat, corn, rye, barley, rice and sorghum, and in other plant sources. Natural wheat gluten and vital wheat gluten are particularly preferred in the methods of this invention.
In one embodiment of the invention, an aqueous colloidal dispersion of gluten-derived proteins and peptides can be prepared by first dispersing gluten in an aqueous medium at a temperature sufficient to hydrate the gluten. Preferably, gluten is added to an aqueous medium (e.g., water) which has been heated to a temperature sufficient to disperse the gluten in the aqueous medium, under agitating conditions. A preferred temperature for adequate dispersion is from about 20° C. to about 75° C., with 45° C. being most preferred. As the gluten becomes dispersed within the aqueous medium, the viscosity of the dispersion increases. Therefore, the amount of gluten that can be dispersed in the aqueous medium will be dictated by the desired viscosity and the further processing steps described herein. For example, the amount of gluten which can be dispersed in the aqueous medium will be from about 10% to about 35% solids, with from about 14% to about 17% solids being most preferred. When adding gluten in the higher solids range, gradual addition of gluten into the aqueous medium is desirable, and will be described in detail below. For purposes of the present invention, “aqueous medium” is defined as water or a solution which is substantially water such as buffer, acid, antioxidant, reducing agent, and/or chelating agent solutions. It is preferred that the aqueous medium, such as water, be pretreated to remove dissolved minerals.
In order to facilitate dispersion of gluten, it is desirable to acidify the aqueous medium to a pH of from about 3 to about 4 using organic and/or mineral acids (e.g., acetic acid, tartaric acid, citric acid, phosphoric acid, hydrochloric acid, lactic acid), with acetic acid and phosphoric acid being preferred. The acid can be added to the aqueous medium prior to, during or after addition of the gluten. The viscosity of the gluten dispersion can be controlled by gradually adding acid to the gluten dispersion early in the reaction. See Example 2.
The resulting aqueous dispersion is treated, under agitation, with a protease to hydrolyze protein contained in the dispersion. A suitable protease is one which is operative at acid pH of from about 1.5 to about 5.5, for example acid fungal protease, such as but not limited to AFP 2000 (Genencor International, Rochester, N.Y.; food grade acid fungal protease obtained by a controlled fermentation of
Aspergillus niger
var.; optimum pH of from about 2.5 to about 3.5 at 37° C. according to the manufacturer). The protein hydrolysis step should be carried out for a period of time suitable to achieve a drop in viscosity. Preferably, the protein hydrolysis reaction should be carried out for about 2 to about 3 hours in order to achieve adequate viscosity and gloss properties of the final product. It has been demonstrated that the degree of protein hydrolysis is important in the final gloss properties of the gluten-derived colloidal dispersions.
The degree of viscosity can be obtained by measuring the time (seconds) that it takes to empty a #2 Zahn cup for monitoring the process or using a Brookfield viscometer for the final product. A preferred viscosity is a gluten dispersion that takes about 16 to about 18 seconds to empty a #2 Zahn cup (Paul N. Gardner Co., Inc., Pompano Beach, Fla.) at 45° C. It is desirable to achieve a viscosity that is compatible with the method by which the colloidal dispersion will be applied to the substrate to be coated. For example, the viscosity should be adequate to atomize the colloidal dispersion through a spray nozzle, e.g., 45 cP for a hand held sprayer; up to 100 cP for a pressurized commercial sprayer.
The degree of gloss is dependent upon the microparticle size of the gluten-derived proteins and peptides. This is controlled by the degree of hydrolysis of the gluten. Adequate gloss properties are based, in part, upon the substrate to be coated and the type of finish desired. Gloss can be measured using known techniques such as by the methods described in the Examples Section. For example, a liquid sample is coated onto a opacity display gloss board and the gloss measurement taken at a 20° angle using a BYK-Gardner Micro-TRI-gloss reflectometer (BYK-Gardner Inc., Silver Spring, Md.) The fraction of light reflected is measured.
After protein hydrolysis is completed to the desired degree, the aqueous colloidal dispersion is heated to a temperature sufficient to gelatinize the starch contained in the gluten such that it can be hydrolyzed in a subsequent treatment step. The temperature should be from about 65° C. to about 95° C. At these temperatures, the protease will become deactivated. The gelatinization step should be carried out for from about 30 minutes to about 60 minu
Duda Mark G.
Mallee Francis M.
Rudie Noel G.
Shulman Mark L.
Hamilton Brook Smith & Reynolds P.C.
Opta Food Ingredients, Inc.
Pratt Helen
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