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
2001-11-14
2003-07-01
Weier, Anthony J. (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
C426S240000, C426S614000
Reexamination Certificate
active
06586037
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a method for improving gelation properties of protein through electron beam irradiation.and the protein treated by the method, as well as a method for gelating the protein whose gelation properties have been improved by the electron beam irradiation and a product containing the protein treated by these methods.
BACKGROUND ART
Denaturation of protein is caused by heat, denaturants such as guanidine hydrochloride and urea, or organic solvents such as ethanol which destroy a stereostructure of the protein. For example, the denaturation by heating causes change in the stereostructure at secondary, tertiary or quaternary level without destruction of a peptide linkage contained in its primary structure and aggregates the denaturated molecules to regularly form a network structure of the protein.
Such a phenomenon can be defined as gelation, which seems to be caused by interaction between the proteins.
Accordingly, for food using albumen, sugar or sugar alcohol is added to raise a denaturating temperature of the. protein, or salts such as sodium salt are added for salting-out in order to prevent the denaturation by heat during manufacturing processes. Further, other methods are employed, for example, a method of removing excess ions and calcium ions as contaminants by demineralization to obtain a clear protein solution, or a method of removing metal salts by using a chelating agent such as a citrate or a polyphosphate for preventing the denaturation. However, these methods do not change the nature of the protein itself but merely control the environmental conditions to adjust the gelation caused by heating.
The protein denatured by heat and thus gelated shows various functional properties, e.g., improvement of viscoelasticity, water absorptivity, consistency, linkage and adherence between particles, as well as stable emulsification and foaming. Therefore, the gelation of the protein plays an important role in manufacturing food such as dairy products, solidified albumen, gelatin protein, thermally-solidified products such as ground meat or fish, soybean protein, plant protein produced by extrusion or fiberization, bread dough and the like.
Regarding whey protein, soybean protein, plasma protein and casein micelle, enhancement of gelation speed and strength of the gel is carried out by adding a calcium salt, an enzyme such as transglutaminase, a gelation agent and a thickener for adjusting the gelation such as carrageenan, gellan gum and xanthan gum, or locust bean gum. Further, the gelation is also performed by first alkalinizing the protein and then neutralizing it or adjusting pH thereof to an isoelectric point.
Also known is a method for treating the protein with radiation and the like (Japanese Unexamined Patent Publications Nos. HEI 6(1994)-327447 and HEI 7(1995)-16085). However, these methods are directed to sterilization, so that there are no observation about improvement of properties of the protein, in particular the gelation properties.
Accordingly, what is demanded is a convenient method for treating the protein to improve the gelation properties of the protein and to give the protein functional properties exhibited by gelation.
DISCLOSURE OF INVENTION
As a result of eager researches to solve the above-mentioned problems, the inventors of the present invention have found that irradiation of the protein with an electron beam improves the gelation properties of the protein. In particular, they have found that a protein exhibiting gelation temperature rose higher than an inherent gelation temperature or ratio of the protein to be gelated increased greater than an inherent ratio can be obtained.
Thus, according to the present invention, provided is a method for improving gelation properties of protein through electron beam irradiation and the protein treated by the method, as well as a method for gelating the protein whose gelation properties have been improved by the electron beam irradiation and a product containing the protein treated by these methods.
BEST MODE FOR CARRYING OUT THE INVENTION
According to the present invention, the protein to be irradiated with the electron beam is not particularly limited as long as it is a protein having gelation properties. Examples of the protein include whole egg, albumen, yolk, ovalbumin, ovoglobulin, soybean flour, soybean protein, wheat flour, wheat protein, wheat glutenin, plasma protein, a concentrate of whey protein, lactoglobulin, taurine, collagen, betaine, mutasteine, ice nucleation protein, lactoferrin, sepia, gelatin, rennet casein, &agr; s 1-casein, &bgr;-casein, lysozyme, hemoglobin, myoglobin, prealbumin, avidin, monellin, milaclin, fibrous protein, mucin, lectin, prothrombin, glycoprotein, myelin basic protein, oxytocin, adrenal cortex and the like. Among them, the albumen, plasma protein, concentrate of whey protein and gelatin are preferable.
The protein may be mixed with a material of a product finally containing protein in the manufacturing or processing step thereof, i.e., the protein may contain various other components.
Examples of the product utilizing the protein during the manufacturing or processing step may be food such as livestock products (ham, sausage, salami, sweet-and-sour-pork, roast pork, broiled pork innards, meatball, corned beef, liver paste, hamburger steak), marine products (Kamaboko, Hanpen, fish paste, ingredients of Oden, oiled tuna), agricultural products (deli, Sukiyaki, fried Tofu with hot meat sauce, stew, curry, meat sauce, soup), dairy products (condensed milk, soya milk, cheese, yogurt, various kinds of modified milk products), egg products (mayonnaise, Dashimaki omelet, custard pudding, marshmallow, mousse, meringue, Chawan-mushi), cream filled in buns, whipped cream, shake, desserts (milk pudding, flan, sweet red-bean soup), frozen sweets (ice cream) and frozen products (frozen foods, frozen cakes), fruit products (jam, candied chestnuts), beverages (juice, coffee-flavored milk, carbonated drink, soft drink, water-like beverage, nutritional drink, functional drink), noodle products (snack noodles, Chinese noodles), wheat flour products (flour for Okonomi-Yaki), soybean products, retort-packed products, hot pack products, products subjected to immersion in boiling water, UHT (ultra high temperature sterilization), HTST (high temperature short time sterilization), high pressure treatment and aseptic packaging. Further, the protein can also be applied to various fields including medical supplies such as toothpaste, mouth care products and mouthwash, quasi drug, feed, film industry and cosmetics.
The method of the present invention is realized by irradiating the protein with an electron beam. In general, the electron beam is generated by an electron beam generating machine. For ex ample, a linear electron accelerator, a van de Graaff's electron accelerator, an area beam type or Cockcroft-Walton's electron beam generating machine and the like are usable.
For the electron beam irradiation, an acceleration voltage to be applied to the electron beam is in the range of 50 KeV to 10 MeV, preferably 300 KeV to 5 MeV, more preferably 300 KeV to 2.5 MeV. With an electron beam applied with an acceleration voltage of less than 50 KeV, expected effects cannot be obtained. Use of an electron beam applied with an acceleration voltage of higher than 10 MeV to food products is prohibited.
In the context of the present invention, dose rate of the electron beam is in the range of 1.0×10
5
to 1.0×10
9
Gy/hr.
The protein to be irradiated with the electron beam may be in any of dried state or dispersed state in water, but preferably is in dried state in the form of film, plate, particles or powders in order to perform sufficient irradiation of the electron beam. In the case of irradiating the protein dispersed in water with the electron beam, the protein may be solidified, if required, by spray-drying, drum-drying, or hot air-drying after the irradiation.
The electron beam irradiation can be performed directly or indirectly to the prote
Hayashi Toru
Sakaue Kazushi
Suzuki Setsuko
Tada Mikiro
Birch & Stewart Kolasch & Birch, LLP
Director of National Food Research Institute, Ministry of Agricu
Weier Anthony J.
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