Food or edible material: processes – compositions – and products – Fermentation processes – Of plant or plant derived material
Reexamination Certificate
2002-06-28
2004-10-12
Wong, Leslie (Department: 1761)
Food or edible material: processes, compositions, and products
Fermentation processes
Of plant or plant derived material
C426S018000, C426S034000, C426S042000, C426S043000, C426S049000, C426S055000, C426S056000, C426S060000, C426S656000, C426S657000
Reexamination Certificate
active
06803062
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to novel processes for producing hydrolyzed protein. More specifically, the present invention relates to processes for easily producing high-quality, highly stable hydrolyzed protein useful for seasonings or the like by hydrolyzing a protein-containing starting material by an action of an enzyme. The present invention further relates to processes for preparing food products by incorporating hydrolyzed protein prepared by such a process in a food product.
2. Discussion of the Background
Various processes are already known for producing hydrolyzed protein from a protein-containing starting material by an enzyme on an industrial production scale.
For example, Japanese Patent Kokai Publication JP-A-51-35,461 discloses a process for producing a liquid seasoning by reacting denatured de-fatted soybeans with an alkaline protease and a peptidase, and Japanese Patent Kokai Publications JP-A-6-125,734, JP-A-9-75,032, and JP-A-9-121,807 disclose a process for producing a seasoning by hydrolysis of various proteins with a protease and a peptidase contained in a culture of a koji mold.
Further, a process for producing a seasoning having a high content of glutamic acid (see Japanese Patent Kokai Publication JP-A-2000-88) or an amino acid mixture with reduced browning (see Japanese Patent Kokai Publication JP-A-2000-14,394) by using a microbial culture obtained by a specific incubation method or by using a specific condition of hydrolysis of a protein-containing starting material have also been reported.
However, such conventional techniques are problematic in that during the production of a hydrolyzate by enzymatic hydrolysis of a starting material containing a solid protein, the quality and the yield of the hydrolyzed protein obtained are decreased due to the growth of microorganisms other than the microorganism used as an enzyme source, so-called contaminants, in the hydrolysis step. In order to solve this problem, bacteriostatic substances such as alcohols, sodium chloride, ethyl acetate, and the like have been employed in the hydrolysis step in the conventional processes (see the above Japanese Patent Kokai Publications JP-A-6-125,734 and JP-A-9-75,032).
However, in these processes, an additional step of separating and removing bacteriostatic substances after the hydrolysis step was required. Especially when sodium chloride was employed as a bacteriostatic substance, it was quite difficult to decrease sodium chloride to less than an appropriate concentration without deteriorating the quality of the resulting hydrolyzed protein. Moreover, it was almost impossible to prevent the occurrence of a so-called brewing odor or soy sauce odor in the hydrolyzed protein obtained by hydrolysis in the presence of bacteriostatic substances. As a result, the range of utilities of the resulting hydrolyzed protein was extremely restricted.
Further, in the conventional processes, attempts were naturally made to subject a starting material containing a solid protein to hydrolysis after removal or sterilization of contaminants incorporated in the protein-containing starting material or a microbial culture as an enzyme source. It is relatively easy to perform hydrolysis of a protein-containing starting material after sterilization thereof on a laboratory scale. However, in industrial mass-production, the prevention of microorganism contamination in the sterilization step and the hydrolysis step is very difficult to perform.
In the commercial production of a liquid seasoning of an enzymatically hydrolyzed protein, it is important to prevent microorganism contamination in view of quality control. The main contamination sources include the protein-containing starting material, the enzyme preparation or the enzyme-containing fermentation broth and the production equipment. In the step of sterilizing a protein-containing starting material prior to the enzymatic hydrolysis, bacteriostatic agents such as alcohols, sodium chloride, ethyl acetate and the like have been employed as stated above. However, incorporation of these bacteriostatic agents into products limits the use of the products. Further, the additional step of removal of such bacteriostatic agents incurs the problem of increased production cost.
With respect to the enzyme preparation or the enzyme-containing fermentation broth, a filtrate of the enzyme solution with an absolute filter or an aseptically fermented enzyme broth is appropriate for the aseptic use in the subsequent hydrolysis process. For the sterilization of the production equipment, there are treatment methods depending on characteristics of the equipment. Washing with an alkaline washing solution or an acid washing solution and steam heating are available and may be performed at a low cost.
Accordingly, the most serious problem among others is to completely sterilize a protein-containing starting material without the use of sodium chloride or alcohols. In particular, the sterilization of a protein-containing starting material containing solid matter involves a lot of difficulties as follows. Looking at a typical method, in which a pulverized protein is dispersed in water and the dispersion is heat-sterilized, it is first found that the dispersion contains solid matter, the inside of which is hardly heated by ordinary heating methods. Further, when the protein concentration in the dispersion is increased, the viscosity of the dispersion becomes quite high, and equipment having a very high power for feeding the dispersion is required, which increases the production cost. In particular, a protein-containing starting material such as wheat gluten includes active gluten which is easy to bind when its powder is dispersed in water. Thus, it cannot be evenly dispersed. Moreover, even if the dispersion can be fed smoothly, the protein ingredients are denatured and solidify inside the unit for the sterilization step, such as a plate-type heat exchanger or a nozzle-type heater, to clog the same.
As one technique to partially solve this problem, a method has been proposed in which a protein-containing starting material is finely pulverized to a diameter of not more than 300 &mgr;m and dispersed in hot water of not less than 80° C., thereby improving the dispersibility of the protein-containing starting material and preventing bubbles from being incorporated into the dispersion at the same time (see Japanese Patent Kokai Publication JP-A-11-313,693). In this method, the dispersing of the protein-containing starting material which was difficult in the past is enabled for protein dispersions having a relatively low concentration. Further, the viscosity of the dispersion is decreased, and bubbles are not incorporated into the dispersion, whereby complete sterilization is enabled in the subsequent sterilization step.
However, in order to decrease the production cost in commercial production, it is necessary to increase the concentration of the protein dispersion and to improve the equipment productivity in the subsequent hydrolysis step. None of the prior techniques are satisfactory for sterilizing such a protein dispersion having a high concentration.
That is, as the concentration of the protein dispersion is increased, the protein-containing starting material is hardly dispersed uniformly. Moreover, when the protein-containing starting material is aggregated in an aqueous medium, it contains air and the heating is not uniform so that complete sterilization is difficult in this state. Further, even though the protein-containing starting material can be dispersed, the viscosity of the dispersion is high, and accordingly, it is difficult to feed for the subsequent step. In theory, it is possible to disperse the protein-containing starting material with a high-performance dispersion vessel and feed the dispersion with a pump for a highly viscous liquid. However, such production equipment is expensive.
With respect to the sterilization step, there are two methods, a direct heating method and an indirect heating method. In th
Ishii Toshimasa
Kojima Junichiro
Nakazawa Hidetsugu
Oyama Inao
Seki Mitsuyoshi
Ajinomoto Co. Inc.
Wong Leslie
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