JP2002320444A - Method for keeping freshness of raw lotus root - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a practical method for keeping the freshness of raw lotus roots, capable of keeping the commercial value of the raw lotus roots, for a long time. SOLUTION: This method comprises washing raw lotus roots in water, pre- treating with a germicide consisting of a chlorite, organic acids and an alcohol, washing the resultant in water, storing with a freshness-keeping agent comprising an alkaline compound and an absorbing material in a bag having gas barrier property, sealing the resultant and holding at a refrigerating temperature of 0-10 deg.C. The raw lotus roots keeps its fresh taste from the field without deteriorating surface color or generating bad smell for two weeks or more.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a practical method for maintaining freshness of fresh lotus roots for a long period of time.

[0002]

2. Description of the Related Art Lotus roots are usually harvested in open-field cultivation from July in summer to March in winter. Recently, however, house cultivation allows harvesting in May, making it possible to harvest and ship almost the whole year. It has become. Harvested lotus roots are usually stored as mud or drained, stored unpacked in cardboard, and shipped.

[0003] Raw lotus root has a high content of iron and vitamin C together with starch and sugars, and after harvesting, is oxidatively degraded by oxygen in the air and is liable to brown or black, and its commercial value is reduced in a short period of time. . For example, about 5 days in winter and 1 in summer
Since it lasts only about 2 days, it can be shipped and consumed as soon as possible after harvesting, or kept temporarily refrigerated,
There were no effective measures to prevent freshness deterioration.

Therefore, various methods for maintaining the freshness of fresh lotus roots for a longer period have been proposed. For example,
(1) In Japanese Patent Application Laid-Open No. 63-196227, root vegetables such as lotus roots have an oxygen permeability of 30 ml / m ² · 24 hr · at
m after vacuum packaging in a gas barrier packaging bag of
A method of heating at 120 ° C. and then storing at room temperature (15 to 30 ° C.) or chilled (0 to 15 ° C.);
Japanese Patent No. 271320 discloses a method of adding an aqueous solution containing 0.001 to 0.05% by weight of organic acids and / or mustard extract and / or 0.05 to 5% by volume of ethyl alcohol to a fresh lotus root and subjecting it to bacteriostatic treatment. In Japanese Patent No. 132334, a water-absorbed and drained fresh lotus root is stored in a bag made of a gas-absorbing and permeable film in which a fine powder of Otani stone is dispersed and contained in a low-density polyethylene film layer and on a surface thereof. And a method of storing in an air atmosphere at a relative humidity of 50 to 60% has been proposed.

However, in the method (1), the heat treatment loses the flavor and crisp texture. In the method (2), there is a concern about residual odor and flavor loss due to mustard extract and ethyl alcohol. According to the method (3), the relative humidity of the air atmosphere surrounding the bag in which the fresh lotus root is sealed and stored is 5
Although it is necessary to keep the content in the range of 0 to 60%, it is difficult to control the humidity of the air atmosphere in a distribution process in which various kinds of products can coexist, and none of them is a practical method.

[0006]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a method for preserving the freshness of fresh lotus roots, which solves the above-mentioned problems of the prior art. An object of the present invention is to provide a method of maintaining freshness without using, without worrying about residual odor, and having good external appearance observation.

[0007]

As a result of studying the method for solving the above-mentioned problems, the present inventor has found that, after harvesting, the lotus roots are usually washed to remove soil rot bacteria by washing attached mud. ,
It has been found that the purpose of maintaining freshness with a long-term security can not be achieved without complete eradication and bacteriostatic treatment. Furthermore, when the lotus root is stored in a gas barrier container at room temperature, sealed, and decompressed, the oxygen in the bag is removed, the oxygen concentration drops rapidly, and deterioration due to low oxygen partial pressure can be prevented. When the oxygen level becomes low, carbon dioxide gas and other deterioration promoting substances are generated due to abnormal respiration. This phenomenon usually reaches its maximum at about 28 hours after sealing at room temperature, from which the quality of the raw lotus root rapidly deteriorates, and in 1-2 days, the appearance deterioration such as partial blackening and the occurrence of fermentation odor are remarkable. It was found to be observed. Further, the internal pressure is applied to the sealed container by the generated carbon dioxide gas, and the container sometimes ruptures, which may lead to exposure of the stored articles to the atmosphere.
It has been found that the purpose of maintaining freshness stably over a long period of time cannot be achieved without proper concentration control by appropriately removing gases generated by abnormal breathing, and the present invention has been completed.

That is, according to the present invention, a fresh lotus root is washed, sterilized with a disinfectant comprising a chlorine-based compound, washed, and then cleaned with a freshness preserving agent containing an alkaline compound and an adsorbed substance. Store in container, 0-10 ° C
And a method for maintaining freshness of fresh lotus root characterized by storing the freshness root.

In the present invention, after harvesting, the fresh lotus root that has been washed, drained, and then treated with a disinfectant is stored in a gas barrier container together with a freshness preserving agent containing an alkaline compound and an adsorbent. By refrigerated storage, 2
Freshness can be maintained for a long period of a week or more.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION Lotus roots dug and harvested from a field are drained after adhering mud is removed by washing with water. Draining is preferably performed to such an extent that a small amount of water remains on the surface, and should not be performed for a long time until the surface is dried. After draining, it is preferable to select lotus roots having good appearance without deep flaws by inspecting the appearance shape, color tone, and surface flaw. The washed, drained, and sorted raw lotus roots are then subjected to a disinfectant / bacteriostatic treatment with a disinfectant.

The germicidal treatment is performed by immersing the fresh lotus root in a liquid containing a germicide. A liquid containing a disinfectant may be uniformly applied or sprayed on the fresh lotus root. The disinfectant used in the present invention contains a chlorine compound as an essential component. As the chlorine-based compound, sodium chlorite, hypochlorous acid, and sodium hypochlorite, which are approved as food additives, are preferably used. In particular, chlorite which has no chlorine odor and a high discoloration prevention effect is used. Sodium is more preferably used. According to the Food Sanitation Law, sodium chlorite concentration should be 0.05% by weight
It is used in the following, and is completely dissolved and washed so that it is not finally detected. By contacting the fresh lotus root with an aqueous solution containing a chlorine-based compound, germicidal and bacteriostatic treatment is performed.

Further, preferred disinfectants are chlorine compounds,
It consists of ethyl alcohol and organic acid compounds, especially chlorite compounds, ethyl alcohol and organic acid compounds. In this case, the germicidal and bacteriostatic treatment is performed by bringing the raw lotus root into contact with a mixed aqueous solution containing the respective components of a chlorine compound, ethyl alcohol and an organic acid compound. Or you may contact sequentially with the aqueous solution which contains each component of a chlorine compound, ethyl alcohol, and an organic acid compound individually.

Examples of the organic acid compounds used in the present invention include organic acids such as citric acid, malic acid, tartaric acid, and succinic acid, and salts thereof. Citric acid is preferably used. Further, two or more of these organic acids or salts thereof may be used in combination. For example, a mixture of trisodium citrate and D, L-malic acid or D, L-tartaric acid can be used. The organic acid compound is usually used as an aqueous solution having a single concentration of 15% by weight or less, preferably 10% by weight or less.

[0014] The sterilized Lotus root is washed with water.
As the water used for washing, preferably, sterilized water is used. After washing, the fresh lotus root is preferably stored in a gas barrier container together with a freshness maintaining agent after draining.

The freshness maintaining agent of the present invention contains an alkaline compound and an adsorbed substance. The alkaline compound contained in the freshness maintaining agent is a basic inorganic substance such as an oxide, a hydroxide or a weak acid salt of an alkali metal or an alkaline earth metal. Among them, calcium hydroxide, magnesium hydroxide and the like are more preferable in view of ease of use and safety (designation of food additives).

The adsorbing substance contained in the freshness maintaining agent of the present invention includes, for example, a silica / alumina adsorbent and a carbon adsorbent. The silica-alumina adsorbent is an adsorbent containing silica and / or alumina components. Examples include perlite, zeolite, silica-alumina gel, silica gel, alumina gel, magnesium silicate, calcium silicate, and the like. The carbon-based adsorbent is obtained by carbonizing and activating a plant-derived substance, or by activating coal. A typical example thereof is activated carbon.

The freshness maintaining agent of the present invention is a composition containing a mixture of a powdery or granular alkaline compound and an adsorbent. The mixing ratio of the composition is the amount of carbon dioxide generated by the raw lotus root, overmaturation, the amount of lower alkynes or alkenes that promote aging, or the amount necessary to adsorb aging accelerators such as aldehydes, usually, The content of the alkaline compound is 5 to 95% by weight and the content of the adsorbent is 95 to 5% by weight. Preferably, the content of the alkaline compound is 50 to 95% by weight and the content of the adsorbent is 5 to 50% by weight. Components other than the alkaline compound and the adsorbent may be added.

The freshness-maintaining agent of the present invention is usually used in the form of a small bag after being packaged with a breathable packaging material. The alkaline compound and the adsorbent may be mixed in advance and then packaged in one small bag, or the alkaline compound and the adsorbent may be simultaneously or sequentially filled and packaged in one small bag so as to be enclosed.
Components other than the alkaline compound and the adsorbent may be added. Further, a small bag packed with an alkaline compound and another small bag packed with an adsorbent may be used together in the same gas barrier container. As a breathable packaging material for packaging the freshness-maintaining agent component, paper, a resin-made perforated film, a nonwoven fabric, a microporous film, and the like are combined, laminated, and opened if necessary. Since fresh lotus root is a food product having high water activity, a breathable packaging material having water resistance is more preferable.

The gas barrier container of the present invention can have various shapes such as a bag shape, a box shape, and a barrel shape. Usually, a bag-shaped container is used. Aluminum foil can be used for the material of the gas barrier container, but a resin film is preferable from the viewpoints of cost and ease of use such as molding. The film configuration is composed of two or more laminated films of a gas barrier film base material layer and an adhesive sealant layer. It is important to use a gas barrier film substrate layer having as high a gas barrier property as possible. As a gas barrier container, the oxygen permeability at 20 ° C. is 30 ml / m ^2.
24 hr · atm or less, preferably 10 ml / m ² · 2
4 hr · atm or less, water vapor permeability 3 g / m ² · 24
hr · atm or less, preferably 2 g / m ² · 24 hr ·
atm or less is preferable. As a gas-bayer container satisfying such conditions, specifically, polyvinylidene chloride-coated stretched nylon (KON) / polyethylene (PE),
KON / nylon (NY) / PE, nylon (NY) or polyester (PET) / saponified expanded ethylene-vinyl acetate copolymer (EVOH) / linear low density polyethylene (LLDPE), expanded polypropylene (OPP)
/ Nylon MXD6 / Low density polyethylene (LDPE)
And the like.

The fresh lotus root, which has been washed, drained and treated with a disinfectant, is stored in a gas barrier container together with a freshness maintaining agent comprising an alkaline compound and an adsorbed substance, and sealed by heat sealing or the like. During sealing, it is preferable to reduce the pressure. The inside of the closed container is preferably in a high humidity state. After sealing, 0-10 ° C,
Preferably, it is stored under refrigerated conditions of 1-5 ° C or less. Thereby, the freshness of the fresh lotus root is maintained for a long period of two weeks or more. The method for maintaining freshness according to the present invention can be suitably used when freshly stored lotus roots produced in open-field cultivation and house cultivation are stored raw for a long period of time.

[0021]

The present invention will be described below in detail with reference to examples. (Bactericidal) The bactericide used in the examples was prepared by the following method. 99.5% by volume ethyl alcohol for food (Nippon Ethanol Co., Ltd.) 38 g Trisodium citrate (Kyowa Hakko Co., Ltd.) 6 g, D, L-malic acid (Kyowa Hakko Co., Ltd.) 5 g, water 51 g A 100 g ethanol formulation was prepared. 5 g of this ethanol preparation was added to 0.05
1kg in addition to 995g of aqueous sodium chlorite solution
g of the disinfectant was prepared. (Physical Properties of KON / PE Laminated Film) The physical properties of the KON / PE laminated film used in the examples were measured by the following methods. (1) Water vapor permeability: g / m ² · 24 hr Measured according to JIS-Z-0208. (2) Oxygen permeability: ml / m ² · 24 hr Oxy-permeability measuring device OXY-TR under the conditions of 20 ° C. and 60% RH
It was measured with AN100 (manufactured by Modern Control).

Example 1 1 kg of harvested raw lotus root (produced in Chiba Prefecture) was thoroughly washed with tap water to completely remove adhering mud, put in a basket and drained for about 30 minutes, and then deep wounds and surface discoloration were observed. We chose a raw lotus root with good appearance observation. The selected raw lotus root is 10 per node.
After cutting to a length of about 10 cm, three groups of about 160 g of the cut fresh lotus root were simultaneously added to the above-described disinfectant at room temperature of 20 g.
C. for 30 minutes. After completion of the immersion, the resultant was washed with boiling sterilized water using a potassium iodide starch solution reagent until no residual chlorine was detected, and drained for about 30 minutes. This is 15
cm × 220 cm polyvinylidene chloride coated stretched nylon (KON) / polyethylene (PE) / linear low density polyethylene (LLDPE) sealant = 15/20/6
0 μm (oxygen permeability 7 ml / m ² · 24 hr (20
° C); water vapor transmission rate 0.57 g / m ² · 24 hr (20
℃)) and at the same time 1.3 g of slaked lime and activated carbon 0.1 g.
3 g of the well-mixed composition was filled with a freshness-maintaining agent filled in a sachet composed of a three-layer breathable material of polyester / paper / polyolefin having fine through-holes, and sealed under reduced pressure. , A specimen was obtained. The three specimens thus prepared are stored in a refrigerator at a temperature of 10 ° C. and a humidity of 30% RH for 15 days, and the humidity, oxygen concentration, and carbon dioxide concentration in the bag are analyzed daily by gas chromatography. At the same time, the surface color of the fresh lotus root was observed, and the gas in the bag was sampled in an amount of 1 ml to conduct an odor test. The results are shown in Table 1.

As can be seen from Table 1, both the appearance color tone test and the odor test were good up to 15 days. The humidity in the bag was around 90% RH. Further, the oxygen concentration in the bag becomes anoxic after one day, and the generated carbon dioxide gas is controlled to a low concentration of 7% or less, desirable storage conditions are maintained, and after the storage period of 2 weeks, It has been confirmed that it has sufficient commercial value. No residual odor of the disinfectant was observed in the fresh lotus root stored for 2 weeks.

Comparative Example 1 In Example 1, except that no freshness preserving agent was used.
The same was done. The results are shown in Table 1. As can be seen from Table 1, when no freshness preservative was used, discoloration and fermentation odor occurred after 10 days, and the commercial value was lost. In addition, the humidity in the bag is around 90% RH, and the oxygen concentration remains anoxic after one day, but abnormal respiration occurs due to the presence of carbon dioxide, and the generation of generated carbon dioxide increases at an accelerated rate. The bag has expanded. After all, the commercial value was less than 5 days.

Comparative Example 2 The procedure of Example 1 was repeated except that the storage temperature was 20 ° C. instead of 10 ° C. The results are shown in Table 1. From Table 1, the fermentation odor was slightly increased after one day, and increased after five days. Eventually, the commercial value was lost in less than five days.

Comparative Example 3 In Example 2, except that the freshness preserving agent C was not used,
The same was done. The results are shown in Table 1. From Table 1, 1
A strong fermentation smell over the course of the day, after 5 days, a strong fermentation smell,
Eventually, the commercial value was lost after one day.

[0027]

[Table 1]

[0028]

According to the present invention, the method for maintaining freshness of fresh lotus roots is as follows.
Even if stored for a long period of more than a week, the color tone and smell are retained,
It has the advantage that no harmful additives are used for treatment and no odor remains.

According to the method of the present invention, the fresh lotus root has practically the freshness of the raw lotus root, the surface color of which does not change over a long period of two weeks or more, the generation of off-flavors does not occur, and the freshly picked flavor is maintained. A method is provided.

Claims (5)

[Claims] 1. A method of washing a fresh lotus root, removing it by a disinfectant containing a chlorine-based compound, washing it, and storing it in a gas barrier container together with an alkali compound and a freshness-retaining agent containing an adsorbed substance. And a method of maintaining the freshness of fresh lotus root, wherein the method is stored at 0 to 10 ° C. 2. The composition according to claim 1, wherein the disinfectant comprises a chlorite compound, ethyl alcohol and an organic acid compound.
The method for maintaining freshness of a raw lotus root described in the above. 3. The method according to claim 1, wherein the alkaline compound contained in the freshness preserving agent is an oxide, hydroxide or weak acid salt of an alkali metal or an alkaline earth metal. 4. The method of claim 1, wherein the adsorbing substance contained in the freshness preserving agent is activated carbon. 5. A gas barrier container having an oxygen permeability of 30.
ml / m ² · 24 hr · atm or less (20 ° C.), water vapor permeability 2 g / m ² · 24 hr · atm or less (20 ° C.)
The method for maintaining freshness of a fresh lotus root according to claim 1.