JP2000217509A - Freshness retaining agent - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a freshness retaining agent capable of preventing the discoloration of a raw vegetable and suppressing the propagation of microorganisms sticking to the vegetable and suitable for preserving the cut vegetable, etc., by including hinokitiol, chitosan and ethanol. SOLUTION: This freshness retaining agent contains hinokitiol in an amount of preferably 5.0-20 wt.% (based on ethanol), chitosan in an amount of preferably 0.005-10 wt.% (based on the ethanol) and the ethanol. Vegetables are preferably brought into contact with an aqueous solution prepared by diluting the freshness retaining agent to 0.1-10 wt.% to carry out the sterilizing treatment of the vegetables or preferably brought into contact with an aqueous solution containing chlorine dioxide and then coated with the freshness retaining agent to conduct the sterilization treatment of the vegetables. Naturally occurring hinokitiol, an alkali metal salt of hinokitiol, an iron complex, etc., of the hinokitiol are preferably used as the hinokitiol.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a freshness preserving agent used for preserving freshness of vegetables and a method of using the same.

[0002]

2. Description of the Related Art In recent years, with the diversification of lifestyles,
In eating habits, there is a growing need for convenience such as simplicity and ease of handling. This is also true of vegetables, which have already been processed to some extent at the time of purchase for simplicity, rationality, and economy, from the viewpoint of storage after purchase, complexity of cooking, and disposal of waste after cooking. There is an increasing tendency to seek vegetable products such as cut vegetables. But,
Vegetables, such as cut vegetables, undergo severe physiological changes due to the cutting of vegetables, so that freshness declines faster than raw vegetables that have not been processed at all, and rot easily proceeds.

[0003] To cope with such problems, conventionally, various methods for avoiding deterioration and deterioration of vegetables and maintaining freshness, for example, using an ethylene adsorbent as a method for maintaining freshness of vegetables and fruits. There are a method using a packaging material containing an antibacterial agent, a method using a disinfectant such as sodium hypochlorite, and the like.

[0004] Ethylene is generated during the aging process of plants and has a function of accelerating the progress of aging of fruits and vegetables, and is a substance which eventually leads to putrefaction. Ethylene removers include porous materials such as activated carbon. There is a method of adsorbing and removing by a method and a method of decomposing with a catalyst.

However, since the ethylene adsorbent is for the purpose of removing ethylene, it cannot be expected to have an antibacterial effect against various bacteria attached to vegetables. Ethylene adsorbent
It is necessary to dispose after use, and there is a disadvantage that industrial waste is increased. In addition, since the ethylene adsorbent is effective when used in combination with a plastic film, it must be treated as waste after use.
In addition, some ethylene decomposition catalysts contain a noble metal such as palladium, which not only increases the cost during production but also causes a problem of soil contamination during waste disposal.

As another method for maintaining the freshness of vegetables, a technique has been disclosed in which vegetables are wrapped in a packaging material containing a safe antibacterial agent to suppress the propagation of various bacteria on the vegetable surface. For example, JP-A-61-108359 discloses a method in which a cyclodextrin inclusion compound containing hinokitiols is contained in a packaging material such as a resin film. Since the effect is limited to the portion in contact with the packaging material, in the case of cut vegetables, there is almost no effect in preventing the cut surface from changing.

[0007] Other main methods of maintaining vegetable freshness include:
A method of treating with a chlorine-based germicide such as sodium hypochlorite can be given. However, when such a disinfectant is used, a process for sufficiently washing the disinfectant attached to the vegetables is required. As described above, immediately after the sterilization treatment, although the germs attached to the vegetables are remarkably reduced, the effect of preventing the germs from growing during the subsequent storage, that is, the antibacterial effect is poor. That is, although the bacteria are reduced once, the fungicide attached to the vegetables is washed away,
Then breed. Alternatively, floating germs adhere to the vegetable surface and propagate.

[0008]

SUMMARY OF THE INVENTION The present invention relates to a freshness preserving agent suitable for use on fresh vegetables, particularly cut vegetables, which prevents discoloration of fresh vegetables and prevents microorganisms adhering to the vegetables. The purpose of the present invention is to maintain freshness by preventing breeding.

[0009]

DISCLOSURE OF THE INVENTION The present invention is characterized in that raw vegetables are treated with an aqueous solution comprising chitosan, hinokitiol and ethanol to prevent discoloration of the raw vegetables and prevent spoilage. Has a remarkable effect on raw vegetables. Vegetables that are the subject of the present invention are not particularly limited, but are damaged quickly with time, and have a problem in maintaining quality, lettuce, cabbage, parsley,
Komatsuna, spinach, honeybee and the like and their cut vegetables can be mentioned. In particular, cut vegetables have cell structures destroyed by shredding, so that microorganisms are easy to propagate, and the accompanying contamination causes a rapid decrease in freshness.

JP-A-2-52222 discloses a freshness preserving agent in which the pH is adjusted by adding an organic acid to a hinokitiol-containing alcohol.
JP-A-6-125704 discloses a freshness preserving agent containing at least one selected from ethanol, sorbitol, glycerins and organic acids, comprising vinegar, ethyl alcohol and chitosan. A freshness preserving agent containing an acid is taught.
The freshness preserving agent disclosed in JP-A-2-5822 has vinegar, ethyl alcohol and chitosan as essential components. In order to use these as they are in foods, the pH must be too low to cause wilting of fresh vegetables and to reduce the unpleasant odor of vinegar, it is necessary to dilute the stock solution before use. However, since the antimicrobial effect cannot be expected in a small amount of any of the above components, the antimicrobial effect is weakened by dilution, the viable cell count immediately after the treatment is sufficiently reduced, and the effect of suppressing the proliferation of the bacteria is insufficient.

The present inventors have conducted intensive studies on the above-mentioned problems, and as a result, vegetables, especially cut vegetables, have been obtained using chitosan,
The present inventors have found that by treating with an aqueous solution comprising hinokitiol and ethanol, it is possible to obtain a vegetable that prevents discoloration of raw vegetables, reduces the propagation of various bacteria, and is less likely to cause a decrease in freshness.

As the hinokitiol used in the present invention, natural hinokitiol, alkali metal salts of hinokitiol such as sodium and potassium salts, or iron complexes of hinokitiol can be used. Since the hinokitiol component has an antibacterial property in a small amount, it is an effective component for preventing germs from growing on vegetables and maintaining freshness.
The freshness preserving agent of the present invention contains chitosan as an essential component, and can effectively exert the effect of the aforementioned hinokitiol component for a long period of time. Since chitosan has antibacterial activity and exerts antibacterial activity over a long period of time,
Perishables can be protected from corruption. In addition, since chitosan has an action of forming a coating, the coating of chitosan containing hinokitiol described above coats the cut surface of vegetables to prevent oxidation by air or browning by enzymes during storage, and The growth of various germs that cause odor can be suppressed, and freshness can be maintained for a long period of time.

Since hinokitiol is hardly soluble in water, it is used by dissolving it in an aqueous solution containing ethanol, as described in JP-A-2-5822. Although hinokitiol has high antibacterial properties even in small amounts, it is difficult to maintain the antibacterial properties over a long period of time because it is easily volatilized. In addition, since ethanol, which is a solvent, also has high volatility, the number of viable bacteria decreases immediately after the treatment, but the bacteria easily propagate thereafter. for that reason,
It was necessary to use more. Then, when chitosan was used as an essential component in fresh vegetables, not only the antibacterial effect during storage but also the sustainability of the browning prevention effect could be dramatically improved. In the present invention, the combination of chitosan, hinokitiol and ethanol dramatically improves the browning prevention effect and the sustainability of the antibacterial effect during storage. That is, since fresh vegetables are coated with the chitosan film containing hinokitiol, the easily volatile hinokitiol component is retained, and the antibacterial effect of the hinokitiol component is exhibited over a long period of time. Although chitosan has a sustained antibacterial activity, its bactericidal activity is lower than that of ethanol or hinokitiol. Therefore, when chitosan is used as a freshness maintaining component, the amount of chitosan used has to be increased. On the other hand, in the present invention, since not only chitosan acts as an antibacterial component, but also hinokitiol is included and fresh vegetables are coated, the volatile hinokitiol component is stably retained, and a small amount of hinokitiol and chitosan When used, an antibacterial effect and a browning preventing effect can be exhibited over a long period of time. In addition, since only a small amount of water-soluble chitosan is used, it is not necessary to use an organic acid such as vinegar necessary for dissolving a large amount of chitosan (Japanese Patent Laid-Open No. 6-1257).
In No. 04, vinegar is an essential component, because chitosan is easily dissolved in an organic acid aqueous solution).

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In order to carry out the present invention, first, hinokitiol and chitosan are dissolved in an alcohol preparation containing ethanol. At this time, the concentration of hinokitiol and chitosan was 5.0 to 20% by weight based on ethanol contained in the alcohol preparation used as the solvent.
A stock solution of a freshness preserving agent is prepared so as to be 0.005 to 10% by weight. As an organic solvent for dissolving hinokitiol and chitosan, ethanol is preferable, but since it is used directly in foods, a brewing alcohol containing ethanol as a main component is preferable. In addition, since ethanol not only has a function as a solvent but also has a bactericidal effect, it is used as a component of the freshness preserving agent in the present invention.

[0015] The freshness preserving agent of the present invention is prepared by diluting a prepared undiluted solution of freshness preserving agent with water or other aqueous solution as it is, and bringing the diluted solution into contact with the surface of vegetables or fruits to prevent a change in color tone and maintain freshness. The effect can be exhibited. When the stock solution of the freshness preserving agent is used by diluting it in an aqueous solution, the concentrations of hinokitiol, chitosan and ethanol are 5.0 × 10 ⁻³ wt% and 5.0 × 10 ⁻⁶ , respectively, based on the aqueous solution at the time of use. The content is preferably adjusted and used so as not to be less than 0.1% by weight. The freshness preserving agent of the present invention contains hinokitiol, chitosan and ethanol as essential components, but if the content of these components is below the above range, the freshness preserving effect cannot be sufficiently exhibited.

In the method for maintaining the freshness of fresh vegetables using the freshness-preserving agent of the present invention, the vegetables are washed and then permeated into an aqueous solution obtained by diluting the freshness-preserving agent for about 1 to 10 minutes. Alternatively, the undiluted solution of the freshness preserving agent as described above or diluted with water or another aqueous solution is sprayed on the surface of the vegetable. Alternatively, as described above, the freshness preserving agent of the present invention can be used in combination with a conventional sterilization method in addition to being used alone in foods. For example, as a method of sterilizing cut vegetables and the like, the use of the above-mentioned chlorine-based disinfectant is a general method, but after performing a disinfection treatment with these chlorine-based disinfectants, the freshness retaining agent of the present invention Is further applied or post-treated such as dipping, so that the growth of viable bacteria after sterilization can be extremely effectively suppressed.

Next, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples. In each example,% is represented by% by weight.

[0018]

[Example 1] (1) Preparation of freshness preserving agent Natural hinokitiol, chitosan, ethanol concentration 75%
Using the brewing alcohol of the present invention,
In addition, stock solutions of the freshness preserving agents of Comparative Examples and Control Examples were prepared. The composition is shown in Table 1.

[0019]

[Table 1]

(2) Comparative Example 5 (Freshness retaining film) For comparison with the freshness retaining agent of the present invention, a freshness retaining film was produced as described below, and Comparative Example 5 was obtained. 1.5 g of cyclodextrin was dissolved in 100 ml of water, 0.2 g of hinokitiol was added, and the mixture was stirred at about 60 ° C. to obtain a precipitate of inclusion bodies. Next, this precipitate was collected and freeze-dried to obtain a cyclodextrin inclusion compound of hinokitiol. 5% aqueous 1.0% suspension of such inclusion compounds
0 g is uniformly applied to 1 m ² of polyethylene film,
It was air-dried at about 40 ° C. to obtain a freshness retaining film (Comparative Example 5).

[Example 2] (Temporal change test) (1) Treatment with a freshness-retaining agent shown in Table 1 Each of the preparations 1 and 2 of the present invention shown in Table 1, Comparative Examples 1 and 2, and a freshness-retaining agent of a control example was 10 ml each. 1 liter of ion-exchanged water was added to the mixture to prepare a 100-fold diluted treating agent. Hereinafter, Examples 1 and 2 are referred to as Examples 1 and 2, respectively, and treatment agents obtained by diluting Examples 1 and 2 are referred to as Examples 3 and 4, respectively. The processing agents obtained by diluting Comparative Examples 1 and 2 will be described below as Comparative Examples 3 and 4, respectively. Approximately 160 g of the cut and washed cut lettuce was immersed in 2 liters of each treatment agent for about 10 minutes to be sterilized. The pasteurized cut lettuce was drained, packaged, and then stored at 10 ° C., and the color change of the cut lettuce was observed over time. The criteria for the evaluation of the change over time are as follows. -: Normal without discoloration ±: Slightly discolored +: Discolored to brown ++: Discolored to brown and smells strange (2) Use of freshness retaining film of Comparative Example 3 About 160 g of cut and washed lettuce was used as a comparative example. A package was prepared using the freshness retaining film of No. 3 and then stored at 10 ° C., and the time-dependent change in the color of the cut lettuce was observed, and the time-dependent change was evaluated in the same manner as in the above-described treatment with the freshness-preserving agent. (3) Results of Freshness Preserving Effect From the results in Table 2, all of the preparations of the present invention or those treated with Comparative Examples 1 and 2 showed less change with time as compared with the control example. It turns out to be good.
In the case of Comparative Example 3 using the freshness retaining film, the freshness retaining effect was limited only to the portion that was in contact with the film. Overall, the results were comparable to the control. On the other hand, the result of the use of the freshness preserving agent of the present invention, the combination of ethanol and hinokitiol,
Or, it can be seen that it is better than a freshness preserving agent containing ethyl alcohol and chitosan. in this way,
It was found that the freshness retaining agent of the present invention further improved the freshness retaining effect due to the synergistic effect of hinokitiol and chitosan.

[0022]

[Table 2]

Example 3 (Test for Effect of Preventing Browning) As described above, the preservative of the present invention has a higher effect of preventing discoloration of vegetables as compared with the case treated with the control example. Then, in order to further confirm this effect, the browning prevention effect was confirmed as described below using the above-mentioned Example 3 and the control example for the effect on the cut edge of vegetables, in which freshness deteriorated most severely. First, using the above-mentioned Example 3 and the control example, the stem cut surfaces of the lettuce were respectively treated. Next, a photograph was taken of the cut surface of the lettuce stem on the third day after the treatment to measure the lightness, and the degree of browning by visual observation was also compared. In order to measure the lightness, the photograph was taken together with the cut section of the lettuce stem and a standard color tone plate. This image was captured using an image capture scanner (manufactured by EPSON).
After importing it into a computer, the image analysis software
age-Pro Plus), the color is corrected from the standard color tone, and then the stem cut surface of the lettuce is R
GB analysis was performed. As described above, the lightness of the cut section of the lettuce stem was measured using the photograph as described above, and the lightness was compared to compare the degree of browning between the freshness-retaining agent of the present invention and the control example. The lightness measurements are red, the three primary colors of light,
It was divided into three colors of green and blue, and only the cut surface of the lettuce stem was continuously performed. Table 3 shows the average values of the lightness of these three colors.

[0024]

[Table 3]

When the cut surface of the lettuce stem was visually observed, the one treated in the control example showed remarkable browning, but the one treated in Example 3 showed almost no browning even on the third day.
Unlike the case where the treatment was performed in the control example, it was recognized that the freshness of the cut was maintained. And from the results in Table 3,
In the case of using the preparation of the present invention, the value of lightness was very large in any color as compared with the case of using the control example, and it was shown that the color of the cut edge was bright, clear, and freshness was maintained.

[Antibacterial Test 1] To confirm the antibacterial properties, the cut lettuce subjected to each of the antibacterial treatments of Example 2 was observed for changes in the number of viable general bacteria and the viable count of coliform bacteria during storage. The results are shown in Tables 4 and 5.

[0027]

[Table 4]

[0028]

[Table 5]

From the results shown in Tables 4 and 5, the antibacterial effect was also maintained for a long period of time against the freshness-retaining agent of the comparative preparation containing neither hikitiol nor chitosan, similarly to the results of the browning prevention effect test. I found that there is.

[Antimicrobial Test 2] The antibacterial effect of the cut vegetables which had been subjected to the conventional sterilization treatment using sodium hypochlorite and further post-treated with the freshness preserving agent of the present invention was observed. That is, about 160 cut and washed
g of lettuce was immersed in a 150 ppm aqueous solution of sodium hypochlorite for about 10 minutes for sterilization. The lettuce subjected to the sterilization treatment was washed with running water for 10 minutes using tap water to remove sodium hypochlorite. The washed lettuce was further sterilized and packaged using the freshness-preserving agent or freshness-preserving film shown in Table 1 in the same formulation as the browning prevention effect test of Example 2, and then packaged at 10 ° C.
And the changes in the number of viable bacteria in general and the number of viable bacteria in the coliform group during storage were observed. The results are shown in Tables 6 and 7.

[0031]

[Table 6]

[0032]

[Table 7]

The control examples in Tables 6 and 7 correspond to cases where only the conventional sterilization treatment using sodium hypochlorite was performed. From the results in Tables 6 and 7, the preparations of the present invention or the comparative preparations both suppress the growth of general viable bacteria and Escherichia coli as compared with the control example, and after sterilization with sodium hypochlorite, It can be seen that there is an effect of continuously suppressing breeding. Comparative Example 3 using freshness retaining film
In the case of, since the effect of keeping freshness is limited only to the contact part with the film,
Antibacterial effect does not appear in the part that did not contact the film,
The effect of suppressing the growth of viable bacteria was almost the same as the control as a whole. On the other hand, when using the freshness preserving agent of the present invention, due to the synergistic effect of hinokitiol and chitosan, compared with the freshness preserving agent of the combination of ethanol and hinokitiol, or the combination of ethanol and chitosan,
It can be seen that such antibacterial properties become more effective.

[0034]

The freshness preserving agent of the present invention comprising hinokitiol, chitosan, and ethyl alcohol exhibits a synergistic freshness preserving effect as compared with the case where the constituent components are used alone. Furthermore, after a sterilization treatment with a chlorine-based germicide, the freshness preserving agent of the present invention is further subjected to post-treatment such as application or immersion, whereby the growth of viable bacteria after sterilization can be extremely effectively suppressed. it can.

Claims (4)

[Claims] 1. A freshness preserving agent comprising hinokitiol, chitosan and ethanol. 2. The freshness preserving agent according to claim 1, wherein the contents of hinokitiol and chitosan are 5.0 to 20% by weight and 0.005 to 10% by weight, respectively, based on ethanol. 3. A method for sterilizing vegetables, wherein the vegetables are brought into contact with an aqueous solution obtained by diluting the freshness preserving agent of claim 2 to 0.1 to 10% by weight. 4. A method for sterilizing vegetables, comprising applying the freshness-preserving agent according to claim 1 to the vegetables after the step of bringing the vegetables into contact with an aqueous solution containing chlorine dioxide.