JPH0499474A - Keeping quality improver for food - Google Patents

Abstract

PURPOSE:To obtain the subject improver, containing a chitosan hydrolyzate consisting essentially of a low-molecular chitosan having a specific molecular weight as an active ingredient, improved in astringency and protein aggregating properties while keeping antimicrobial properties and usable without impairing texture and appearance of a food. CONSTITUTION:The objective improver containing a chitosan hydrolyzate consisting essentially of a low-molecular chitosan having 6000-10000 molecular weight as an active ingredient. Furthermore, the chitosan hydrolyzate is preferably obtained by enzymic hydrolysis of chitosan with a microorganism such as Verticillium AF9-V-156 (FERM P-11377) belonging to the genus Verticillium.

Description

[Detailed description of the invention] [Industrial application field]

The present invention relates to a durability improving agent for foods. More specifically, the present invention relates to a food shelf life-promoting F agent containing a decomposed product of chitosan having a specific molecular weight as an active ingredient.

[Conventional technology] In recent years, interest in food additives has increased, and in particular, synthetic preservative T4, synthetic sterilizing agents, synthetic coloring agents, etc. not only have strict legal regulations and usage restrictions, but also tend to be avoided by general consumers. It is in. Among these, synthetic preservatives such as sorbic acid, benzoic acid, and dehydroacetic acid are often used as food preservatives to extend the shelf life of foods.
Due to the strong distrust among general consumers regarding the safety of No. 4, the amount used in food products has reached a plateau. Under these circumstances, natural antibacterial agents are attracting attention. However, the theory that it is safe because it is natural no longer holds true.
Even for natural antibacterial agents, confirmation of their safety is required individually. Under such circumstances, chitosan is attracting attention for its safety and effectiveness. Chitosan is 2-amino-2-deoxy-D-glucose (
Glucosamine) is a basic homopolysaccharide with β-(1-4) bonds in a linear chain, and industrially it is usually obtained by deacetylating natural chitin contained in the shells of crabs, shrimps, etc. It will be done. Regarding the safety of chitosan, Arai et al. (Tokai Suikenho, 56.89 (198 g)) YaM
. Sugano et al. (Nutrition Report
s International. 18.531 (1978), TheA+erica
n Journal or Cth n1cal Nut
It has been confirmed by the test of Rition, 33.787 (1980)). Chitosan is known to have various physiological activities and functionalities. Regarding antibacterial properties, antibacterial properties against some molds (C, R, As1an et al., Experiment
ntal Mycology, 3.285 (1
979). D. F. Kendra et al. Experimenta
l Mycology, 8,276 (+984)
, P.S., 5tossel et al., Phytopat
hologische Zeitschrift, Il
l, 112 (1984)) and antibacterial properties against bacteria (Chemistry and Biology, 21.635. (1,983), Polymer Digest, February issue, 14. (1985)
)) etc. are known. However, chitosan obtained by deacetylating natural chitin is a polymer and exhibits extremely high viscosity when made into a solution. In addition, chitosan has characteristics such as its characteristic astringency, protein aggregation effect, and ability to dissolve in water only under acidic conditions, which limits the types of foods in which it can be used. Therefore,
There are also proposals for the effectiveness of low-molecular-weight chitosan and oligos obtained by chemically or enzymatically decomposing chitosan as food preservatives. For example, it has been reported that chitosan that has been lightly degraded by chitosanase has stronger antibacterial properties against bacteria than untreated chitosan (Uchida, Food Chemical, 2.22 (19H), Japanese Patent Publication No. 1-56755).
) or there is. However, in this report, the degree of decomposition of chitosan is expressed as the ratio of the amount of reducing sugar produced to the amount of original chitosan, and no information is provided regarding the molecular weight of chitosan produced. do not have. As a report that clearly indicates the molecular weight of chitosan, Molecule! 10
．． A food preservative containing a decomposed product of chitosan of 000 to 50,000 as an active ingredient (Japanese Patent Application Laid-open No. 1-128775) was added to the food preservative (Japanese Patent Publication No. 1-128775). Regarding oligosaccharides, there are JP-A-1-291799 and the like. However, the antibacterial properties of oligosaccharides are known to be very weak, as reported by Uchida mentioned above, and thus lack practical use. [Problems to be solved by the invention] When trying to use chitosan to improve the shelf life of foods,
In addition to antibacterial properties, improvement of chitosan's shortcomings such as astringency and protein aggregation should also be considered at the same time. However, there are only a few examples in which the relationship between the molecular weight of chitosan and its suitability as a food shelf life enhancer has been comprehensively investigated in detail from the viewpoints of antibacterial properties, taste properties, aggregation properties, solubility, etc. The present invention aims to provide a food shelf life improver containing chitosan as an active ingredient, which has improved drawbacks such as taste, aggregation, and solubility so that it can be used in a wide range of foods while maintaining chitosan's antibacterial properties. It was done for a purpose. [Means for Solving the Problem] As a result of extensive research in order to achieve the above object, the present inventors have found that by enzymatically decomposing chitosan and using a decomposed product of chitosan having a specific molecular weight distribution, The present invention has been developed based on the discovery that the above objectives can be achieved, and the present invention has been completed.That is, the present invention is directed to a long-lasting food product containing chitosan decomposition products whose active ingredient is low-molecular chitosan with a molecular weight of e, ooo to 10.000. The raw material chitosan used in the present invention may be high-molecular-weight chitosan obtained by deacetylating natural chitin by a conventional method such as alkali treatment, but it may also be a high-molecular-weight chitosan obtained by deacetylating natural chitin by a conventional method such as alkali treatment. There are no particular restrictions on the molecular weight of chitosan, and chitosan of any molecular weight can be used as a raw material.In addition, under basic or neutral conditions,
Colloidal chitosan, which is chitosan dispersed and suspended in water, can also be used as a raw material. It also has a high degree of deacetylation (95
Both chitosan (~100%) and commonly used chitosan with a low degree of deacetylation (65~95%) can be used as raw materials. It is possible to reduce the molecular weight of chitosan both chemically and enzymatically, but enzymatic decomposition is preferable in order to obtain a product with a relatively narrow molecular weight transition. There are no restrictions on the enzyme used for decomposition, as long as it is an enzyme that can decompose chitosan, or microorganisms belonging to the genus Particillium (Vertieilliuv sp.), especially microorganisms belonging to the genus Particillium AP9-V156 (FER). No. 11377) and its mutant strains are most desirable. A patent application has already been filed for a method for producing this enzyme by the same applicant as the present application (Japanese Patent Application No. 81531/1999). In order to obtain a chitosan decomposition product whose main component is low-molecular-weight chitosan with a molecular weight of -86,000 to 10,000, it is necessary to conduct 1,61 tests for each enzyme used and set the reaction conditions. For detailed examination of conditions, analysis of molecular weight distribution by gel filtration is very effective. The combination of reaction po and temperature can be freely selected within the action range of the enzyme used.
If chitosanase produced by the V-156 strain or its mutants is used, the reaction can be carried out efficiently if the pH is 3.0 or higher. Therefore, the amount of acid added during chitosan dissolution is adjusted so that the pH of the solution after dissolution is 3.0. Enzyme reactions can be carried out without adding alkali by simply maintaining the temperature above 0. The reaction temperature can be selected within the range of 30 to 80° C., which is usually the operating temperature of chitosanase, but since the reaction at high temperatures advances the browning of chitosan, it is desirable to perform the reaction at as low a temperature as possible in order to avoid browning as much as possible. In the case of chitosanase produced by Particillium AF9-V-156 strain, the enzymatic reaction can be carried out efficiently at 30 to 87°C. Then solve the molecule j;1 distribution If? However, the enzyme concentration and reaction time may be adjusted to set conditions such that chitosan having a molecular weight of 1-1 can be obtained. The antibacterial agent for food according to the present invention maintains antibacterial properties, improves the astringency and protein aggregation properties of conventional chitosan, and has solubility near neutrality, making it suitable for foods for the elderly. Can be applied. For example, grain-based products such as bread, noodles, and rice; processed vegetable and fruit products such as pickles and jam; dairy products such as cheese, butter, and margarine; meat;
Meat products such as ham, bacon, and sausage, seafood-added T products such as kamahoko, chikuwa, and tsukudani, and steamed buns. Sweets such as Yokan fil--gi, seasonings such as miso, soy sauce, 1 noodle soup, 1 sauce, processed foods such as tofu, soy milk, boiled beans, etc., as well as raw foods such as salmon, fish, and fruits and vegetables. It can also be used in salmon foods, side dishes, etc.

[Example] Hereinafter, the present invention will be explained in detail with reference to Examples, but the present invention is not limited to these Examples in any way. Example 1 Molecular weight of Katatosan and food shelf life improver In order to examine in detail the relationship between the suitability of chitosan and 17, we decomposed chitosan with chitosanase to prepare four decomposition products with different molecular weight distributions, and evaluated them for their antibacterial properties, taste (astringency), protein aggregation properties, The solubility was compared. (1) Preparation of chitosan decomposition product Low viscosity chitosan L1.WP (manufactured by Kimitsu Chemical Industry ■ Trade name:
degree of deacetylation 75-85%) 50g of pure water 8001
1i1 was added, and while stirring, 50 mJl of 1.0M acetic acid was added to dissolve the chitosan. After completely dissolving the liquid volume i,
A 5% chitosan solution was prepared. The pll of this solution was 4.2. Chitosanase produced by Particillium sp. F9-V-156 strain was added to this chitosan solution at a ratio of 10slJ/1llj, and 3
Oxygen reaction was carried out at 0°C. 2 hours after the start of the reaction (degraded product A)
, after 6 hours (degradation product B), 18 hours (degradation product C), and 42 hours (decomposition product D), 200-80
After deactivating the enzyme by heat treatment for 15 minutes, analysis of molecular weight distribution, antibacterial test, flocculation test, and solubility test were conducted. (2) Analysis of molecular weight distribution of chitosan decomposition products In other words, a solution of chitosan decomposition product diluted to 0.2% 1
mN, gel filtration applied carrier 5ephacryl S-2
Column packed with 00 (manufactured by Pharmacia) (15*■
The molecular weight distribution was estimated by gel filtration. As a molecular weight marker, molecular weight 510,000.7
1. 39,000.9.400 dextran (manufactured by Sigma), chitohexaose hydrochloride (molecular weight 1.200, manufactured by Seikagaku Corporation), and glucosamine hydrochloride. As a result, the decomposition product A has a molecule i40.0
00 or more, decomposition product B has a molecular weight of 10,000 to 4
Widely distributed around 0,000, decomposition product C has a molecular weight of 8
．． It was found that the decomposition products were distributed centering around molecular weights of 2.000 to 3.000, with [l[lO~10.000 being the center. (3) Measurement of reducing sugar content: The reducing sugar content of undegraded chitosan (LLVP, 5% solution) and each chitosan decomposition product (A-D, each 5% solution) was measured by p
- Measured by the HBA II method (M, Lever, Nal. Bjochem, 47, 273 (1972)). Note that glucosamine was used as a standard substance. As a result, the amount of each reducing sugar was 0.42
7 mg/lN, decomposition product A: 1.07mg/lj,
Decomposition product B: 2.37g+g/14! , decomposition product C:
6.56mg/Ij. Decomposition product D: 12.5 mg/-. (4) Antibacterial property test: The antibacterial property of each decomposition product obtained in (2) above was tested by the following method. Commercially available ordinary bouillon medium (manufactured by Eiken Chemical Co., Ltd.) 1
Dissolve 8g in 1,000ml of distilled water and adjust the pH to 6.
．． The solution was adjusted to 0, and 41 Ilil was dispensed into test tubes, followed by autoclaving. Using this test tube, prepare a 2-fold dilution series of each decomposition product, and add an overnight culture solution of 112 strains of E. coli to the appropriately diluted E. coli to each test tube at a ratio of 1.05/IIIN. It was cultured with shaking at 87°C for 72 hours. The lowest concentration at which no bacterial growth was observed was defined as the MIC (minimum inhibitory concentration) of each decomposition product. The results are shown in Table 1. MIC is 1
When it was 25 ppm or less, it was expressed as Δ when it was 0.250 to 500 ppm, and when it was 500 ppI or more it was expressed as X. (5) Taste Test Each decomposition product was made into a 0.5% solution and tested for each astringency by 10 panelists. The results are shown in Table 1. If the bitterness was not felt, it was marked as ○, if it was slightly felt, it was marked as △, and if it was felt considerably, it was marked as ×. (6) Protein aggregation test: 0.5% of each decomposition product was added to the bouillon medium, and the presence or absence of dregs formation was examined. The results are shown in Table 1. O in the table
Symbols indicate no formation of sludge, △ indicates slight formation of sludge, and × indicates formation of sludge. (7) Solubility test: Make each decomposition product into a 1% solution and add 1N sodium hydroxide to the solution.
The H was raised to 7.0 and the presence or absence of precipitate formation was examined. The results are shown in Table 1. Cases in which no precipitate was formed and chitosan was dissolved were indicated by ○, and cases in which chitosan precipitate was formed were indicated by ×. From the results of (4) to (6), the decomposition product C1, that is, the molecule Q
B. A decomposed chitosan product whose main component is low-molecular-weight chitosan with a molecular weight of 000 to 10,000, maintains antibacterial properties, improves astringency and protein aggregation, and further improves pu'y,
It was found that it has a very high solubility and is ideal for use in foods. The effect of adding chitosan decomposition product C obtained in Example 1 to food was tested by lightly pickling Chinese cabbage. Salt 3.5%, chemical seasoning 04%, liquid seasoning 0. Make a pickling solution with a composition of 】%,
Chitosan decomposition product C (5% as chitosan solid content) was added at 0.2% (0.01% as chitosan solid content) and 1.0% (0.05% as chitosan solid content), respectively, to test group 1. and test group 2. A group to which no chitosan decomposition product was added was used as a control group, and the Chinese cabbage weight was packed in bags such that the weight of each pickling liquid was -1:1, and the vegetables were stored at 10° C. with the pickling solution added. Table 2 shows the results of examining the degree of cloudiness of the pickling solution over time. In addition, in the table, - indicates that the pickling solution is not cloudy, + indicates that the pickling solution is slightly cloudy, and ++ indicates that the pickling solution is considerably cloudy. As for the taste, we asked 10 people to taste it (
, I received an evaluation of 7, and the evaluation was that there was no sense of reluctance in any of the test groups. From this result, it was found that decomposed product C has the effect of increasing the shelf life of pickles by several days or more depending on the amount added without changing the taste of the pickles. Table 2 Shallow Soaking Preservation Test Example 3゜The effect of adding chitosan decomposition product C prepared in Example 1 to custard cream was tested. 20g egg yolk, 40g sugar
1 10g flour, 10g cornstarch, 420g milk
Based on the basic composition, chitosan decomposition product C has a chitosan solid content of 0.02% (test group 1) and 0.01% (test group 2), respectively.
) and make custard cream according to the usual method.
, was prepared. Each sample was stored at 2D°C and changes in appearance were observed. The results are shown in Table 3. - in the table means no carbonization,
”- means slightly carbonaceous, ++ means clear cystic failure. Third
As is clear from the table, chitosan decomposition product C was able to significantly improve the shelf life of custard cream. A sensory test was also conducted by 10 panelists at the same time, and all aspects such as taste, color, and aroma were the same as the control group, and no quality problems were observed. Table 3 Custard cream storage test

【Effect of the invention】

The food shelf life improver of the present invention has improved astringency and protein aggregation properties of conventional chitosan while maintaining antibacterial properties, so it can be used without impairing the texture or appearance of foods. Moreover, since it maintains solubility near neutrality, it can be used in many types of foods, making it extremely useful in the food industry.

Claims (1)

[Scope of Claims] 1. A shelf life improver for food whose active ingredient is a chitosan decomposition product whose main component is low-molecular-weight chitosan with a molecular weight of 6,000 to 10,000. 2. The food shelf life improver according to claim 1, wherein the chitosan decomposition product is an enzymatic decomposition product of chitosan. 3. The enzyme is produced by the genus Verticillium.
umsp. 3. The food shelf life improver according to claim 2, which is chitosanase produced by a microorganism belonging to the following. 4. The shelf life improving agent for foods according to claim 3, wherein the microorganism belonging to the genus Verticillium is Verticillium AF9-V-156 (Feikoken Bokuyori No. 11377).