Food or edible material: processes – compositions – and products – Fermentation processes – Of isolated seed – bean or nut – or material derived therefrom
Reexamination Certificate
2001-09-07
2003-03-25
Hendricks, Ketih (Department: 1761)
Food or edible material: processes, compositions, and products
Fermentation processes
Of isolated seed, bean or nut, or material derived therefrom
C426S430000
Reexamination Certificate
active
06537597
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a process for producing a soybean protein hydrolysate. More specifically, it relates to a process for producing a soybean protein hydrolyzed with an enzyme in a high yield with minimizing formation of dregs upon dissolution.
BACKGROUND ART
Products obtained by hydrolyzing proteins with a proteolytic enzyme have better absorbability upon digestion than that of proteins without proteolysis, and are utilized in various fields such as health food and the like. In particular, it is expected to use them in sports drinks, drinks for nutrition, and the like.
Up to now, JP 61-254153 A, JP 1-269499 A, JP 2-23885 A, 4-190797 A, JP 8-322471 A, JP 10-271958 A, etc. disclose processes for producing enzymatic decomposition products obtained by hydrolyzing animal and vegetable proteins with enzymes. In general, after hydrolysis of proteins with an enzyme, heat treatment is carried out in these known processes so as to inactivate the enzyme, sterilizing the products, and so on. In particular, anaerobic thermophilic bacteria often cause problems in these kinds of products and, normally, thorough heat sterilization is required.
In addition, although a water-soluble fraction and a water-insoluble fraction are separated after hydrolysis, conventional drinks containing protein hydrolysates are liable to form a small amount of a precipitate (dregs) during storage and this is a problem. In general, improvement of quality causes decrease in a yield, whereas increase in a yield is liable to form more dregs during storage. This is also a problem.
OBJECTS OF THE INVENTION
One object of the present invention is to provide a process for producing a soybean protein hydrolyzed with an enzyme in a high yield with minimizing formation of dregs upon dissolution.
SUMMARY OF THE INVENTION
The present inventors have studied intensively to solve the above problems. As a result, it has been found that the above problems can be solved by two step heat treatment, wherein, after hydrolysis of a protein with an enzyme, the hydrolyzation mixture is subjected to a step for heating lightly, followed by cooling to separate insolubles before subjecting the mixture to heat sterilization. Thus, the present invention has been completed.
That is, the present invention is a process for producing a soybean protein hydrolysate which comprises hydrolyzing a soybean protein solution with a proteolytic enzyme, heating (a) and cooling the hydrolyzation mixture, separating and removing insolubles from the mixture to obtain a supernatant and heat-sterilizing (b) the supernatant.
In comparison with heat treatment generally employed for inactivating an enzyme or sterilization, the above heating (a) is preferably carried out under such mild conditions that heating time is 10
5.25−(0.05×T)
minutes (wherein T is heating temperature (°C.)) or shorter, because heat sterilization (b) is carried out afterward. Inactivation of the enzyme and sterilization can be effected by heat sterilization (b) of the supernatant after separating and removing insolubles.
Preferably, heating (a) is carried out until the temperature rises to 75° C. or higher, and cooling is carried out until the temperature drops to 60° C. or lower. Preferably, insolubles are separated and removed at a pH of the soybean protein solution of 4.0 to 6.2, or the soybean protein solution contains an alkaline earth metal compound or a protein flocculating agent.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
As a raw material for preparing the soybean protein solution of the present invention, which is derived from soybeans and is available inexpensively, there can be used soybean milk, concentrated soybean protein, isolated soybean protein, defatted-soybeans, soybean whey protein and the like. Among them, soybean milk or isolated soybean protein is preferred. When concentrated soybean protein or defatted-soybeans is used, separation of “okara (insoluble residue)” after enzymatic decomposition tends to be difficult. And, it takes much time to collect whey protein, and whey protein has an inferior flavor. As an alkali to be used for preparing the soybean protein solution, or adjusting pH of the hydrolyzation mixture, sodium hydroxide can be used. Potassium hydroxide can also be used in view of nutrition. As an acid, preferably, an organic acid such as citric acid is used in view of a flavor.
The concentration of the soybean protein solution to be subjected to the enzymatic treatment is 1 to 30% by weight, preferably 5 to 15% by weight, more preferably 8 to 12% by weight. Even if the concentration is low, it will not be an obstacle to the process itself. However, the productivity is lowered, which causes increase in the production cost of a soybean protein hydrolysate. When the concentration of the soybean protein solution is too high, a large amount of an enzyme is required for decomposing the protein sufficiently. This may be caused by polymerization of protein hydrolysates once formed by hydrolysis one another, and is undesirable.
As the proteolytic enzyme to be used in the present invention (protease), an exoprotease or endoprotease can be used alone or in combination thereof. The enzyme may be that derived from animals, vegetables or microorganisms. Specifically, serine proteases (trypsin, chymotrypsin, etc. derived from animals; subtilisin, carboxypeptidase, etc. derived from microorganisms; etc.), thiol proteases (papain ficin, bromelain, etc. derived from vegetables) and carboxy proteases (pepsin derived from animals) can be used. Further, the specific examples thereof include Protin FN (trade name of protease manufactured by Daiwakasei K. K.) derived from
Aspergillus oryzae
, Actinase (trade name of protease manufactured by Kaken Seiyaku K. K.) derived from
Streptomyces griseus
, Alkalase (trade name of protease manufactured by Novo) derived from
Bacillus licheniformis
, Protin A (trade name of protease manufactued by Daiwakasei K. K.) derived from
Bacillus subtilis
, and the like. In addition, examples of enzyme preparations containing endoproteases include Protease S manufactured by Amano Seiyaku K. K., Protin AC-10 manufactured by Daiwakasei K. K. and the like. Examples of proteolytic enzymes containing exo- and endoproteases include Protease M manufacuted by Amano Seiyaku K. K.
Conditions for hydrolysis of the present invention vary to some extent according to a particular kind of the proteolytic enzyme to be used. However, in general, it is preferred to use the enzyme in an amount sufficient for hydrolyzing soybean protein in a pH range at a temperature effective for the enzyme activity. When pH is 5 to 10, preferably 6 to 9, formation of a salt by neutralization can be reduced and this is desired in view of using the hydrolysate for a salt-restriction diet (e.g., alimental infusion, etc.).
The degree of hydrolysis is about 20 to 98%, more preferably about 50 to 90% in terms of a soybean protein decomposition rate expressed by a solubilization degree of a protein component in 15% trichloroacetic acid. Although time for acting a proteolytic enzyme varies depending upon the activity of a particular proteolytic enzyme to be used and its amount, normally, it may be about 5 minutes to 24 hours, preferably about 30 minutes to 9 hours. When the enzymatic decomposition time is too long, putrefaction is liable to take place.
The hydrolyzed soybean protein solution is subjected to heating (a) and cooling prior to the step for separating and removing insolubles therefrom. This heating (a) is effected lightly in comparison with that for heat sterilization. When this heating is effected excessively so that the heating time is in excess of 10
5.25−(0.05×T)
minutes or shorter, a material causing dregs upon dissolution of the decomposed product is formed, presumably, due to formation of a fraction eluted from a precipitated fraction of the soybean protein hydrolysate formed by hydrolysis. This is undesirable. On the contrary, when this heating is not effected, flocculation capability of insolubles is p
Akasaka Yoshimi
Maeda Hirokazu
Nakamori Toshihiro
Fuji Oil Company Limited
Hendricks Ketih
Wenderoth , Lind & Ponack, L.L.P.
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