JP5916116B2 - Oyster fruit peeling method and peeled oyster fruit - Google Patents

Description

  The present invention relates to a method for peeling oyster fruit and a peeled oyster fruit.

In recent years, consumption of fruits has been sluggish, and it has been pointed out that one of the reasons for this is the psychology of consumers who refrain from peeling before eating. In fact, the market for cut fruits that have been peeled and ready to eat has been expanding in recent years.
However, most of the cutting process relies on human hands. In particular, a lot of labor is required for the peeling process.

Therefore, an enzyme skinning technique has been developed for oyster fruits in an attempt to increase the efficiency of the skinning process (Patent Document 1).
This enzyme skinning technology for oyster fruits introduces an exogenous enzyme solution containing polygalacturonase into the cell space of the pericarp tissue and acts to dissociate the intercellular adhesion by decomposing the pectin in the cell space. Based on the mechanism.
For this reason, when it is going to perform the enzyme peeling of the oyster fruit whose surface layer is covered with the cuticle, the pre-processing which ensures the path | route for introduce | transducing an enzyme liquid into a skin tissue is needed.

  For this reason, the method of performing the penetration treatment process of a cuticle using a metal needle etc. before an enzyme treatment process is proposed (patent documents 2).

  However, this treatment of perforating as uniformly as possible on the surface of each individual fruit is cumbersome when performed manually, and improvement has been sought.

  Therefore, oyster fruit scratching devices have been proposed (Patent Document 3 and Patent Document 4), but the structure of the device is complicated, making the device itself expensive, and difficult to use except for expensive products. .

Japanese Patent No. 3617042 JP 2008-86258 A Japanese Patent No. 4174440 JP 2010-046030 A

  The present invention solves the above problems, and can perform a process for ensuring a pathway for introducing an enzyme solution into the pericarp tissue of an oyster fruit easily and inexpensively, without using a physical perforation process. An object of the present invention is to provide a method that can efficiently peel the oyster fruit, and a peeled oyster fruit obtained by this method.

The outermost cuticle of the outer skin of oyster fruit is composed of a cuticle layer composed of wax (inner cuticle), a hard-degradable cutin and cutane, and an outer wax layer (outer cuticle wax). ing.
The role of wax in maintaining the strength of the cuticle layer in oyster fruit is significant, and the present inventors removed the wax from the cuticle layer of oyster fruit by an organic solvent (chloroform: methanol (1: 1) solution) treatment. In addition, it was found that the mechanical strength of the cuticle layer is greatly reduced even in the variety “Furuyu” which is difficult to peel.

Based on this knowledge, the present inventors have made further studies on treatments that exhibit similar effects and can be applied to food processing.
As a result, as a process in the previous stage of the enzyme treatment, the cuticle layer is decomposed and removed by a chemical treatment in a solution, in which a treatment with a surfactant is performed instead of a conventional physical perforation treatment, It has been found that the permeability of the enzyme solution to the pericarp tissue can be increased, and the present invention has been completed based on this finding.

That is, the present invention according to claim 1 includes a first step of treating oyster fruits with a surfactant, a second step of heat-treating oyster fruits after performing the first step, and a second step. A third step of performing enzyme treatment on the oyster fruit after performing the step, and a fourth step of removing at least the outer skin of the oyster fruit after performing the third step are characterized in that they are sequentially performed. The present invention provides a method for peeling oyster fruit.
The present invention according to claim 2 provides the method according to claim 1, wherein the treatment with the surfactant in the first step is a treatment of immersing the oyster fruit in water containing the surfactant. is there.
The present invention according to claim 3 provides the method according to claim 1 or 2, wherein the surfactant used in the first step is a nonionic surfactant.
The present invention according to claim 4 provides the method according to claim 3, wherein a polyglycerol fatty acid ester is used as the nonionic surfactant.
The present invention according to claim 5 is the method according to any one of claims 1 to 4, wherein the second step is performed by heating the oyster fruit after performing the first step in a weak alkaline aqueous solution. Is to provide.
The present invention according to claim 6 provides the method according to any one of claims 1 to 5, wherein the enzyme used in the third step has a function of decomposing pectin.
In the present invention according to claim 7, in the fourth step, at least the outer skin of the oyster fruit is removed by rubbing the oyster fruit after running the third step in running water. The method in any one of -6 is provided .

According to the present invention, it is possible to perform a process for securing a route for introducing an enzyme solution into the pericarp tissue of an oyster fruit easily and inexpensively without using a physical perforation process. Can be peeled.
That is, according to the present invention, as a treatment in the previous stage of the enzyme treatment, the physical perforation treatment that has been conventionally performed is not necessary, and the fruit is peeled only by the solution treatment of treating with a surfactant. Is possible.
The peeled oyster fruit obtained by the production method of the present invention not only has a texture unique to oysters but also has an excellent appearance, and becomes a cut fruit that can be eaten immediately after being peeled.

Hereinafter, the present invention will be described in detail.
The present invention relates to a method for peeling oyster fruits, a first step of treating oyster fruits with a surfactant, a second step of heat-treating oyster fruits after performing the first step, and a second step. A third step of performing enzyme treatment on the oyster fruit after performing the step, and a fourth step of removing at least the outer skin of the oyster fruit after performing the third step are characterized in that they are sequentially performed. Is.
Here, each of the first step and the second step plays a role as a pre-stage treatment of the third step (enzyme treatment step), and in that order, the first step is treated in advance. The second step can be referred to as pretreatment.

<First step>
The first step is a step of treating oyster fruit with a surfactant.
The oyster fruit may be a plant belonging to the genus Diospyros, for example, a fruit of Diospyros kaki. Specifically, for example, "Furuyu", "Hirakuno Mu", "Tone Sassei", "Koshu Hyakume", "Jiro", "Ichida", "Saijo", "Ehime", "Nishimura Wassei", etc. Variety can be mentioned, but the present invention is not limited to these. Note that the varieties “Hirakuno Mu”, “Ehime”, and “Furuyu” tend to have poor peelability in this order. Moreover, as long as it is used for food, either sweet potato or astringent may be sufficient.
In addition, before performing a 1st process, it is good to wash | clean oyster fruits beforehand using a water-flow conveyor etc.

In the first step, the oyster fruit as described above is treated with a surfactant.
The treatment with the surfactant may be performed by immersing the oyster fruit in water containing the surfactant or by applying the surfactant to the oyster fruit, but is not limited thereto. .
As the treatment with the surfactant in the first step, if there is no other special need, the subsequent second and third steps can also be treated using a water tank. The method of immersing oyster fruit in water containing a surfactant, which enables treatment in a water tank, is more preferable.

When oyster fruits are immersed in water containing a surfactant, the concentration of the surfactant in the water containing the surfactant is 300 to 20000 ppm, preferably 500 to 15000 ppm, more preferably 800 to 12000 ppm.
In this case, in varieties that are good or not so bad, such as oyster cultivar “Hirakumu Mutsu” and oyster cultivar “Ehime”, the concentration of the surfactant in the water containing the surfactant is: 300-2000 ppm, preferably 500-1500 ppm, more preferably 800-1200 ppm is sufficient.
On the other hand, in the oyster cultivar “Furuyu” having poor peelability, the concentration of the surfactant in the water containing the surfactant is 1000 to 20000 ppm, preferably 1500 to 15000 ppm, more preferably 1800 to 12000 ppm.

  The immersion time is 8 to 24 hours, preferably 10 to 20 hours, more preferably 14 to 18 hours. In addition, if it is immersion within this time, it has been confirmed that the weight increase due to water absorption of oyster fruits and the decrease in sugar content are very fine and have no problem.

  In the case of oyster cultivar “Furuyu” having poor peelability, it is preferable to apply a surfactant. In this case, a stock solution of the surfactant or a high-concentration diluted solution thereof may be used.

As the surfactant to be used, a nonionic (nonionic) surfactant is preferable.
The HLB value of the nonionic surfactant is preferably from 10 to 19, more preferably from 13 to 18, and even more preferably from 15 to 17.

Examples of nonionic surfactants include polyglycerin fatty acid esters and sucrose fatty acid esters, with polyglycerin fatty acid esters being particularly preferred.
Examples of the polyglycerol fatty acid ester include decaglycerol monolaurate and decaglycerol monocaprylate, but are not limited thereto.
As the fatty acid of the polyglycerol fatty acid ester, those having 8 to 22 carbon atoms can be used, and those having 8 to 14 carbon atoms are particularly preferable, and examples thereof include caprylic acid, lauric acid, and myristic acid.

As said surfactant, what is recognized as a food additive is preferable. Specifically, for example, Ryoto (registered trademark) polyglycerin L-7D (manufactured by Mitsubishi Chemical Foods Co., Ltd .; decaglycerin monolaurate; HLB value 17) and Ryoto (registered trademark) polyglyceride Examples thereof include ester CE-19D (manufactured by Mitsubishi Chemical Foods, Inc .; decaglycerin monocaprylate; HLB value 15). All of these are recognized as food additives produced using glycerin derived from vegetable oil and fatty acid derived from vegetable oil.
Since Ryoto (registered trademark) polyglycerin CE-19D is more hydrophobic than Ryoto (registered trademark) polyglyceride L-7D, the effect on the wax component of the cuticle layer is different. It is preferable to use a surfactant suitable for each type.

In addition, in this 1st process (processing process with surfactant), when it is the process under high pH, it exists in the tendency for blackening to come out easily, and pH is used using alkalis, such as sodium bicarbonate (sodium hydrogencarbonate). It is not necessary to adjust the amount, and treatment with a surfactant alone is sufficient.
In addition, as a first step, a route for introducing an enzyme solution into oyster peel tissue even if treatment with an alkali such as sodium bicarbonate (sodium bicarbonate) is performed instead of treatment with a surfactant. (Crack) cannot be secured.

  By performing the first step (a treatment step with a surfactant) as described above, it is simple and inexpensive without using a physical perforation treatment in combination with the subsequent second step (step for heating oyster fruit). In addition, a route (crack) for introducing the enzyme solution into the oyster peel tissue can be secured.

  Since the first step is not a conventional scratching operation of the skin, but a solution treatment using a surfactant, the operation can be simplified. In addition, even when mechanized, a special device is not required, so that there is an advantage that the cost can be reduced as compared with the conventional mechanical device.

<Second step>
In the subsequent second step, the oyster fruit after the first step is heat-treated. By performing heat treatment in the second step following the first step, cracks are generated in at least the cuticle of the outer skin of the oyster fruit, and the enzyme solution in the enzyme treatment in the subsequent third step is used as the oyster peel. A route for introduction into the organization can be secured. Moreover, the pectin degrading enzyme activity inhibitory factor in an oyster fruit can be inactivated by this heat processing.

The heat treatment in the second step is not particularly limited as long as the oyster fruit is uniformly heated, but it is preferably performed using heated water. The heat treatment using heated water may be performed, for example, by immersion in hot water, or by spraying steam (water vapor). However, considering that it is preferable to perform the heat treatment for a short time from the viewpoint of preventing the softening of the pulp, it is most preferable to perform the heat treatment by dipping in hot water, which is more suitable for short time heating.
As the water, any water such as tap water, distilled water, deionized water, and water having high hardness can be used.

The temperature of the hot water in this case is 80 to 100 ° C, preferably 95 to 100 ° C.
The heat treatment time is 20 to 300 seconds, preferably 25 to 270 seconds, more preferably 30 to 240 seconds.

  The heat treatment time is preferably shorter from the viewpoint of preventing the softening of the pulp, and it is preferable to quickly cool after the heating.

After performing the heat treatment, it is possible to minimize the deterioration of the quality of the pulp by cooling quickly.
In this case, the cooling is desirably performed so that the surface temperature of the oyster fruit can be quickly lowered (specifically, within 60 seconds, preferably within 30 seconds) to about 40 ° C. or less. The cooling means is not particularly limited, but it is preferable to place the fruit in running water or immerse the fruit in ice water.

In particular, if the second step (heat treatment step) is performed using a weak alkaline aqueous solution such as sodium bicarbonate instead of water, it becomes possible to increase cracks in the pericarp of oyster fruits, and the third step. Since a route (permeation route) for introducing the enzyme solution in the enzyme treatment in this step into the pericarp tissue of oyster fruit can be secured, oyster fruit can be peeled more easily, which is preferable.
In particular, unlike cultivars that are relatively easy to peel, such as “Hirakuno Mutsu”, in the case of oyster varieties such as “Ehime”, which has a slightly worse peelability, the second step (heat treatment step) is performed with baking soda, etc. It is preferable to use a weakly alkaline aqueous solution. Furthermore, in the case of oyster cultivar “Furuyu” with poor peelability, it is essential to perform the second step (heat treatment step) using a weakly alkaline aqueous solution such as baking soda.

That is, it is preferable to immerse the oyster fruit after the first step in a weak alkaline aqueous solution at a temperature of 80 to 100 ° C, preferably 95 to 100 ° C.
Here, “weakly alkaline” refers to a pH exceeding 8.0 and 11.0 or less in terms of pH.
Here, it is not necessary to have a high pH, and “weakly alkaline” can be sufficiently peeled by performing the following third step (enzyme treatment step) and fourth step (outer skin removal step). . If it is not “weakly alkaline” but is “alkaline” exceeding pH 11.0, for example, quality deterioration such as blackening occurs in the fruit after peeling, which is not preferable. Further, if the pH is “neutral” of 6.0 or more and 8.0 or less, it is not preferable because the effect of use cannot be obtained.

  Sodium bicarbonate (sodium hydrogen carbonate) is preferably used to make the weak alkaline aqueous solution, but it is not necessarily limited thereto. Sodium bicarbonate usually shows around pH 8. When an alkaline aqueous solution such as sodium carbonate or sodium hydroxide is used instead of a weak alkaline aqueous solution, even if the concentration is low, the fruit skin after peeling or peeling tends to turn brown or black. is there.

The concentration of the baking soda used is 0.1 to 8.0%, preferably 0.5 to 7.0%, more preferably 0.8 to 6.0%. Here, if the concentration of sodium bicarbonate is less than 0.1, the effect is not sufficient. On the other hand, when the concentration of baking soda exceeds 8.0%, it is not preferable because dissolution of sodium bicarbonate at room temperature is difficult.
In general, a higher concentration of baking soda can be applied to many varieties, and a sufficient pretreatment effect can be obtained by heating in a shorter time.
In the oyster cultivar “Ehime”, etc., the heat treatment effect in the same treatment time can be increased as the concentration of baking soda increases.

  In the case of varieties that are relatively easy to peel, such as “no plain”, those with advanced maturity can be heated by using heated water (boiling water) without using a weakly alkaline aqueous solution. The cuticle layer of the outermost layer of oyster peel can be peeled off.

Therefore, as the second step (heat treatment step), specifically, the oyster fruit after the first step is immersed in a boiling aqueous solution containing sodium bicarbonate and subjected to the heat treatment as described above. It is preferable that it is cooled quickly after that.
By performing such a heat treatment in a sodium bicarbonate boiling aqueous solution, it becomes possible to increase cracks in the skin more effectively than a heat treatment using mere water, and the subsequent third step (enzyme) It is possible to secure a route for introducing the enzyme solution into the oyster peel tissue performed in the treatment step.

  In addition, in this second step (heat treatment step), when a surfactant is added, there is a tendency that cracks generated in the skin after heating tend to increase, and the surfactant has a certain effect on weakening the skin. I understand that. However, if a mixed solution of baking soda and surfactant is heated with a strong heating power, the solution may foam and spill out, and from the viewpoint of work safety, addition of the surfactant to the baking soda solution is not preferable.

<Third step>
In the third step, the oyster fruit after the second step is subjected to an enzyme treatment.
Following the first step and the second step, by performing the enzyme treatment in the third step, the path created by performing the first step and the second step (of the pericarp of oyster fruit The enzyme solution can be introduced into the oyster peel tissue through a route for introducing the enzyme solution in the enzyme treatment in the third step, which is created by causing cracks in at least the cuticle, into the oyster peel tissue.

  In the third step (enzyme treatment step), an enzyme pectinase (pectin degrading enzyme agent) having a function of degrading pectin contained in the cell wall of oyster fruit is used, and commercially available pectinase enzyme agents include cellulase. Since there exists what has activity, you may use the enzyme agent which has cellulase activity other than such pectinase activity.

That is, in the third step (enzyme treatment step), peeling can be performed only with pectinase activity, but an enzyme agent having cellulase activity in addition to pectinase activity may be used.
However, when an enzyme agent having cellulase activity in addition to pectinase activity is used, the peeled flesh is softer than an enzyme agent having only pectinase activity. Accordingly, an enzyme agent having only pectinase activity or an enzyme agent mainly composed of pectinase activity is suitable.

As pectinase (pectin degrading enzyme agent), polygalacturonases derived from Aspergillus awamori, trigalacturonases, trichospolone Examples include polymethoxypolygalacturonases derived from penicillatam (Trichosporon penicillatum).
Among these, “protopectinases” derived from yeast and yeast-related microorganisms such as Trichosporon penicillatum are preferable. Specifically, for example, protopectinase IGA (manufactured by IGA Bioresearch Corporation) can be mentioned. This is basically an enzyme agent having only pectinase activity.

  Moreover, as an enzyme agent which has cellulase activity other than pectinase activity, the enzyme agent which mainly has pectinase activity and has cellulase activity like Peelzym (made by Novozymes) can be mentioned, for example.

  In addition, in the case of an enzyme agent having pectinase activity but strong cellulase activity, such as Acemocellulase KM (manufactured by Kyowa Kasei Co., Ltd.), the softening of the flesh after peeling is large, and in some cases, the flesh is pegged. This is not preferable because of the failure.

In the third step (enzyme treatment step), pectinase (pectin degrading enzyme agent), which has a function of degrading pectin, does not affect the enzyme action like water, buffer solution, preferably distilled water. It can be used as an enzyme-containing solution in which an enzyme is dissolved in the solution. As the water, any water such as tap water, distilled water, deionized water, and water having high hardness can be used, but distilled water is most preferable as described above.
The concentration of the enzyme in the enzyme-containing solution is not particularly limited, but it is preferable to use an enzyme-containing solution diluted so that the pectinase activity is around 100 U / ml. More preferably, an enzyme-containing solution diluted so that the pectinase activity is 80 to 120 U / ml, particularly preferably an enzyme-containing solution diluted so that the pectinase activity is 90 to 110 U / ml is used.

  As an aspect of the enzyme treatment in the third step (enzyme treatment step), the enzyme-containing liquid is sprayed or applied to the surface of oyster fruit, or the oyster fruit is immersed in the enzyme-containing liquid. Although an aspect is mentioned, the aspect which immerses an oyster fruit in the said enzyme containing liquid from the viewpoint of a uniform process is the most preferable.

The enzyme treatment in the third step (enzyme treatment step) may be performed at a temperature of 10 to 55 ° C, preferably 25 to 37 ° C.
Therefore, it is most preferable to immerse the oyster fruit in the enzyme-containing solution at a temperature of 10 to 55 ° C, preferably 25 to 37 ° C.

  The enzyme treatment time in the third step (enzyme treatment step) is not particularly limited, but is usually 2 to 8 hours, preferably 3 to 7 hours, and more preferably 4 to 6 hours.

  In the third step (enzyme treatment step), it is not necessary to add a surfactant. For example, in the case of a variety that is difficult to peel, a surfactant is added as necessary. Is also possible.

  By performing this third step (enzyme treatment step), a path created by performing the first step and the second step (causing a crack in at least the cuticle of the pericarp of oyster fruit) Through the created route for introducing the enzyme solution in the enzyme treatment in the third step into the oyster peel tissue), the enzyme solution can be introduced into the oyster peel tissue to be in a collapsed state.

<4th process>
In the fourth step, at least the pericarp of the oyster fruit after the third step is performed.
By performing this fourth step (outer pericarp removal step), the persimmon pericarp tissue that is in a collapsed state by the third step (enzyme treatment step) can be removed from the persimmon fruit surface.

The outer skin removal means performed in the fourth step (outer skin removal step) may be a means that can remove the oyster skin tissue that has been collapsed in the third step (enzyme treatment step) from the surface of the oyster fruit. There is no particular limitation, and for example, it is carried out using a known peel remover in addition to means such as rubbing by hand, rubbing with a glove, using a rotating brush, or combining these with running water. And so on.
Among these, the pericarp is removed by hand-rubbing under running water or using a rotating brush under running water because it does not take time and does not damage the surface of the oyster fruit after removing the persimmon skin structure. Most preferably. By performing the removal treatment under running water, the enzyme solution can be removed together with the advantage that the pulp does not have to be fully ripe.

In the present invention, it is necessary to sequentially perform the first to fourth steps described above, and the object cannot be achieved unless this order is satisfied.
For example, even if the first step (treatment step with a surfactant) is performed after the second step (heat treatment step), the object cannot be achieved.

In the method of the present invention, the first step (treatment step with a surfactant) described above is carried out in a water tank, the second step (heat treatment step) is carried out in a boiling water bath, and the third step (enzyme treatment step). Can be carried out in a thermostatic water bath.
As described above, in the method of the present invention, all of the steps from the first step to the third step can be performed in the water tank, so that the water tank can be diverted by changing the solution for each process. . Moreover, it is also possible to process continuously by providing the conveying apparatus which couple | bonds between each tank.

As described above, oyster fruit can be efficiently peeled.
The oyster peeled fruit thus obtained can be used as it is as a food.
That is, the peeled oyster fruit obtained by the production method of the present invention becomes a cut fruit that can be eaten immediately after being peeled. Moreover, the manufacturing method of this invention can be utilized also as the peeling pretreatment of dry fruit processing.

  EXAMPLES The present invention will be described in detail below with reference to examples, but the scope of the present invention is not limited by these examples.

<Example 1> Variety "Hirakawa Mu"
(1) 1st process (treatment process with surfactant)
At room temperature, oyster fruit (variety “Hirakone Mutsu”) was treated with a nonionic (nonionic) surfactant [Ryoto (registered trademark) polyglycerester L-7D (manufactured by Mitsubishi Chemical Foods, Inc .; decaglycerin monolaurate). HLB value 17] was immersed overnight (16 hours) in a 1000 ppm (0.1%) aqueous solution of Example 1. At this time, the pH was not particularly adjusted.
By this treatment, the outermost layer of the persimmon fruit peel could be cracked.

  In addition, when performing the 1st process using this surfactant, sodium bicarbonate (sodium hydrogen carbonate) or sodium carbonate is used in combination (use of 1.0% concentration and 5.0% concentration respectively) Although alkaline conditions were used, not only the skin peeling effect could not be improved, but also when sodium carbonate was used in combination, blackening occurred particularly when the concentration was high, so the pH was adjusted in the first step. I thought it was not necessary.

(2) Second step (heat treatment step)
The oyster fruit subjected to the above treatment was immersed in 3 L of hot water (95 to 100 ° C.), subjected to a heat treatment for 30 seconds, and then immediately cooled with ice water. Thereby, the surface temperature of the oyster fruit was reduced to 40 degrees C or less within 30 seconds.

(3) Third step (enzyme treatment step)
Prepare a 5.0% aqueous solution of protopectinase IGA (manufactured by IGA Bioresearch Corporation) or a 0.2% aqueous solution of acemocellulase KM (manufactured by Kyowa Kasei Co., Ltd.) at a room temperature (15-25 ° C.) and a capacity of 5 L. The oyster fruit that had been subjected to the above treatment was immersed in this water tank and subjected to enzyme treatment for 5 hours.

As a result, when Acemocellulase KM (manufactured by Kyowa Kasei Co., Ltd.) was used, softening of the flesh was observed and partial erosion occurred, but protopectinase IGA (manufactured by IGA Bioresearch Corporation) was used. If so, no such softening was seen.
Accordingly, it was found that pectinase activity alone is sufficient as an enzyme, and that cellulase activity is undesirable because the flesh softens.
Therefore, only protopectinase IGA (manufactured by IGA Bioresearch Corporation) was used in the following steps.

(4) Fourth step (external skin removal step)
The oyster fruit subjected to the above treatment was taken out and rubbed lightly in running water.
As a result, the outer pericarp tissue of the broken oyster fruit was removed.
At this time, the workability (peeling property) of peeling of the peel was evaluated according to the following six criteria. The results are shown in Table 1.
Levels 0 to 2 were determined to be “impossible” (outside the allowable range), and levels 3 to 5 were determined to be “higher than possible” (within the allowable range).

[Criteria for workability of skin detachment]
・ 0: Impossible; no peeling at all.
・ 1: Impossible; Peel partly. Does not peel at all depending on the part.
・ 2: Impossible; level that can be removed if force is applied for a long time (more than 3 minutes).
・ 3: Yes; more force and time than Level 5 are required to detach the skin. It takes about 2 minutes.
・ 4: Good; more power than level 5 is required to detach the skin. The time required is about 1 minute.
・ 5; Excellent; Detachment of skin is short and easy. It takes less than 30 seconds.

  The highest evaluation (level 5) is based on the case where the skin is scratched with a sword and then heat treatment, enzyme treatment, and removal of the outer skin are performed. Assuming that the skin can be peeled off, the level 5 indicates that the skin can be easily detached in a short time with the same force and time.

  According to the results shown in Table 1, it was possible to easily remove the peel in a required time of about 1 minute by performing the treatment with the surfactant (level 4), and scratching the peel using Kenzan. It can be seen that peelability close to that of Reference Example 1 (level 5) in which the treatment was performed was obtained. From a different viewpoint, this invention does not need to be treated one by one using Kenzan, and the present invention, which can also be continuously treated with a solution, can efficiently peel off oyster fruits. I can say that.

<Experimental Example 1> Variety “Furuyu”; Implementation of Surfactant Treatment Step / Heat Treatment Step and State of Peel Skin Persimmon fruits (variety “Furuyu”) at room temperature under the conditions shown in Table 2 in the first step ( (Surfactant treatment step) and second step (heat treatment step), the state of the skin before and after the heat treatment is visually confirmed, and the following six stages (af) judgment criteria It was evaluated with. The results are shown in Table 2. For reference, an example in which treatment with water was performed instead of treatment with a surfactant was also shown.
The variety “Furuyu” is a variety that has a hard skin and is unlikely to crack.

[Criteria for skin state]
・ A: Many long cracks are generated ・ b: Long cracks are generated ・ c: Small cracks are partially generated ・ d: Many wrinkles are generated ・ e: Wrinkles are generated ・ f: No change

  In addition, although the flesh can be seen if it is a “crack”, the “wrinkle-like thing” indicates a state where the flesh cannot be seen before the cuticle film is torn.

According to the results in Table 2, although the skin was hard and cracks did not easily occur, although the variety “Furuyu” was treated with the surfactant, there was no change before the heat treatment. It can be seen later that a small crack has occurred.
On the other hand, when the treatment with water was performed instead of the treatment with the surfactant, it was found that there was no change before and after the heat treatment.

<Experimental example 2> Variety “Hirakuno Mu”; Examination of surfactant concentration conditions In Example 1, the nonionic (nonionic) surfactant in the first step [Ryoto (registered trademark) Polyglyceride L -7D (Mitsubishi Chemical Foods, Inc .; decaglycerin monolaurate) was used in the same manner as in Example 1 except that various concentrations were changed [0 ppm (use only distilled water), 14 ppm, 57 ppm, 285 ppm, 571 ppm]. I went.
Table 3 shows the evaluation results of the workability (peeling property) of peeling the skin.

  As a result, no clear concentration dependence of the nonionic (nonionic) surfactant was observed with respect to the peeling effect, but when combined with the results of Example 1, a higher surfactant concentration tends to be preferable. It was observed.

<Experimental Example 3> Variety “Hirakuno Mutsu”; Baking Soda Addition Experiment In Example 1, when performing the heat treatment in the second step, sodium bicarbonate was added to hot water at 0.1%, 1.0%, and 5. The same procedure as in Example 1 was conducted except that a weak alkaline aqueous solution was added by 0%.
Table 4 shows the evaluation results of the workability (peeling property) of the peel removal.

  As a result, compared with the case of only hot water, even when baking soda was added, no particular difference was observed in the peeling effect. Therefore, it was found that the hot water treatment is sufficient in the case of the variety “Plainkumu”, which is relatively easy to peel, without the need to use baking soda.

<Examples 2 and 3> Variety "Ehime"; Examination of baking soda concentration (1) First step (treatment step with surfactant)
At room temperature, oyster fruit (variety “Ehime”) was treated with a nonionic (nonionic) surfactant [Ryoto (registered trademark) polyglycerester L-7D (manufactured by Mitsubishi Chemical Foods, Inc .; decaglycerin monolaurate; HLB) Value 17] (Example 2) or nonionic (nonionic) surfactant [Ryoto (registered trademark) polyglycerin CE-19D (manufactured by Mitsubishi Chemical Foods, Inc .; decaglycerin monocaprylate; HLB value 15) ( The sample was immersed overnight (16 hours) in the 1000 ppm aqueous solution of Example 3), at which time the pH was not particularly adjusted.
By this treatment, the outermost layer of the persimmon fruit peel could be cracked.

  In addition, when treated with Ryoto (registered trademark) polyglyceride L-7D (Example 2), of course, when treated with Ryoto (registered trademark) polyglycerin CE-19D (Example 3), The occurrence of flesh injuries such as blackening of the skin was not observed, and there was no particular difference in the skinning effect between the two.

(2) Second step (heat treatment step)
The oyster fruit subjected to the above treatment was immersed in 3 L of hot water (95 to 100 ° C.) containing sodium bicarbonate at the concentration shown in Table 5, and subjected to heat treatment for 60 seconds or 120 seconds, and then immediately for 60 seconds each. Alternatively, it was quenched with ice water for 120 seconds. Thereby, the surface temperature of the oyster fruit was reduced to 40 ° C. or less within 60 seconds or 120 seconds, respectively.

(3) Third step (enzyme treatment step)
Prepare a 5.0% aqueous solution of protopectinase IGA (manufactured by IGA Bioresearch Corporation) or a 0.2% aqueous solution of acemocellulase KM (manufactured by Kyowa Kasei Co., Ltd.) at a room temperature (15-25 ° C.) and a capacity of 5 L. The oyster fruit that had been subjected to the above treatment was immersed in this water tank and subjected to enzyme treatment for 5 hours.

As a result, when Accremo Cellulase KM (manufactured by Kyowa Kasei Co., Ltd.) was used, softening of the pulp was observed, but when Protopectinase IGA (manufactured by IGA Bioresearch Corporation) was used, No softening was seen.
Accordingly, it was found that pectinase activity alone is sufficient as an enzyme, and that cellulase activity is undesirable because the flesh softens.
Therefore, only protopectinase IGA (manufactured by IGA Bioresearch Corporation) was used in the following steps.

(4) Fourth step (external skin removal step)
The oyster fruit subjected to the above treatment was taken out and rubbed lightly in running water.
This removed the pericarp tissue of the broken oyster fruit. The remaining state of the outer pericarp tissue was visually evaluated with a five-step criterion. The results are shown in Table 5.

  According to the results of Table 5, if the heat treatment time is 120 seconds, even if 0.1% baking soda is added to hot water, it takes some time, but the peelability is within the allowable range. I understand that.

In addition, it turned out that the crack generate | occur | produced clearly in the 2nd process (heat-treatment process) by putting sodium bicarbonate 0.1% in hot water. Next, when 1.0% of sodium bicarbonate was added to the hot water, peeling was observed in the cuticle layer. Furthermore, it was found that when 5.0% baking soda was added in hot water, some of the stone cells under the cuticle layer were separated.
Therefore, in the case where the skin peelability is an intermediate variety “Ehime” between the varieties “Hirakuno Mu” and the varieties “Furuyu”, it is preferable to heat-treat in a weak alkaline aqueous solution (in sodium bicarbonate), and It was found that the peeling effect increased depending on the concentration of baking soda.
However, when 0.1% baking soda is added to hot water when the heat treatment time is 60 seconds, cracks occur, but workability in the fourth step is inferior, and it is not necessarily from the viewpoint of work efficiency. It turns out that it is not excellent.

<Examples 4 and 5> Variety "Furuyu"
(1) 1st process (treatment process with surfactant)
Nonionic (nonionic) surfactant [Ryoto (registered trademark) polyglycerin L-7D (manufactured by Mitsubishi Chemical Foods, Inc .; decaglycerin monolaurate) on the surface of oyster fruit (variety “Furuyu”) at room temperature (Example 3) or a nonionic (nonionic) surfactant [Ryoto (registered trademark) polyglycerin CE-19D (manufactured by Mitsubishi Chemical Foods, Inc .; decaglycerin monocaprylate) (Example 4) In this case, the pH was not adjusted.

  In addition, when treated with Ryoto (registered trademark) polyglyceride L-7D (Example 4), of course, when treated with Ryoto (registered trademark) polyglycerin CE-19D (Example 5), Although the occurrence of flesh damage such as blackening of the skin was not observed, the peeling effect was better when it was treated with Ryoto (registered trademark) Polyglycerin CE-19D.

(2) Second step (heat treatment step)
Immediately after the above-treated oyster fruit was immersed in 3 L of hot water (95-100 ° C.) containing 5.0% baking soda and subjected to heat treatment for 60 seconds, 120 seconds or 240 seconds, respectively. Each was quenched with ice water for the same time as the heat treatment time. Thereby, the surface temperature of the oyster fruit was reduced to 40 degrees C or less.

(3) Third step (enzyme treatment step)
Prepare a 5.0% aqueous solution of protopectinase IGA (manufactured by IGA Bioresearch Corporation) or a 0.2% aqueous solution of acemocellulase KM (manufactured by Kyowa Kasei Co., Ltd.) at a room temperature (15-25 ° C.) and a capacity of 5 L. The oyster fruit that had been subjected to the above treatment was immersed in this water tank and subjected to enzyme treatment for 5 hours.

As a result, when Accremo Cellulase KM (manufactured by Kyowa Kasei Co., Ltd.) was used, softening of the pulp was observed, but when Protopectinase IGA (manufactured by IGA Bioresearch Corporation) was used, No softening was seen.
Accordingly, it was found that pectinase activity alone is sufficient as an enzyme, and that cellulase activity is undesirable because the flesh softens.
Therefore, only protopectinase IGA (manufactured by IGA Bioresearch Corporation) was used in the following steps.

(4) Fourth step (external skin removal step)
The oyster fruit subjected to the above treatment was taken out and rubbed lightly in running water.
This removed the pericarp tissue of the broken oyster fruit. The remaining state of the outer pericarp tissue was visually evaluated with a five-step criterion. The results are shown in Table 6.

According to the results in Table 6, it can be seen that when 5.0% baking soda is added in hot water, the peelability is improved when the heat treatment time is 120 seconds or longer.
Therefore, in the case of the variety “Furuyu”, which is difficult to peel, it is preferable to heat-treat in a weak alkaline aqueous solution (in sodium bicarbonate), to make the concentration as high as possible, and to further reduce the heat-treatment time. It turned out that it is good to make it long (120 seconds or more).

<Experimental Example 4> Variety “Furuyu”: Judgment of cracks in skin after heat treatment after treatment with surfactant For oyster fruit (variety “Furuyu”) at room temperature under the conditions shown in Table 7, the first Perform the process (surfactant treatment process) and the second process (heat treatment process), and cracks that occur in the peel after heat treatment are divided into the following 6 stages (A to F) depending on the cracked part and the density. ). The results are shown in Table 7. For reference, an example in which the surfactant treatment was not performed was also shown.

The surfactant is a nonionic (nonionic) surfactant [Ryoto (registered trademark) polyglycerester L-7D (manufactured by Mitsubishi Chemical Foods, Inc .; decaglycerin monolaurate) (Example 3) or nonion. Using a system (nonionic) surfactant [Ryoto (registered trademark) polyglycerin CE-19D (manufactured by Mitsubishi Chemical Foods Co., Ltd .; decaglycerin monocaprylate)], it was treated overnight (16 hours).
The heat treatment was performed for 120 seconds under the conditions shown in Table 7 and immediately quenched with ice water for 120 seconds. Thereby, the surface temperature of the oyster fruit was reduced to 40 degrees C or less within 120 seconds.
In addition, ultrasonic treatment in an organic solvent (chloroform: methanol (1: 1) solution) was performed for 30 minutes using an ultrasonic cleaner VS-P100 (As One Corporation).

The variety “Furuyu” is a variety that has a hard skin and hardly cracks after heat treatment.
The stalk side (side with stickiness) is particularly hard. Cracks are more likely to occur on the top side of the fruit (opposite to the side).

[Criteria for determining cracks in the skin]
-A: Fruit top side, dense. Fruit pattern side, dense. Many cracks occur to the periphery of the grinder.
-B: Fruit top side, dense. Fruit pattern side, coarse. Long cracks occur on the stalk, but the number is small.
-C: Fruit top side, dense.
-D: Fruit top side, coarse. Long cracks occur on the top of the fruit, but the number is small.
E: A small short crack partially occurred.
-F: It does not occur at all.

According to the results in Table 7, it can be seen that by treating with a surfactant before heat treatment, cracks can be effectively increased, although it does not reach ultrasonic treatment in an organic solvent.
In particular, according to the results of Table 7, in the case of the variety “Furuyu”, which has a hard skin and hardly cracks after heat treatment, cracks can be effectively increased by performing heat treatment in an aqueous sodium bicarbonate solution. I understand.
Therefore, it is considered that a route for introducing the enzyme solution into the pericarp tissue of oyster fruit can be secured, and as a result, the persimmon fruit can be efficiently peeled.

The technology of the present invention is expected to be widely applied to primary processing in the manufacture of processed oyster fruits such as cut fruits and dried fruits.
Further, the present invention is expected to develop and provide a mechanical device that is cheaper than the existing automated machine for fruit peeling.

Claims (7)

  A first step of treating oyster fruits with a surfactant, a second step of heat-treating oyster fruits after performing the first step, and an enzyme treatment of oyster fruits after performing the second step A method for peeling off oyster fruit, comprising sequentially performing a third step of performing and a fourth step of removing at least the outer skin of the oyster fruit after the third step.   The method according to claim 1, wherein the treatment with the surfactant in the first step is a treatment of immersing the oyster fruit in water containing the surfactant.   The method according to claim 1 or 2, wherein the surfactant used in the first step is a nonionic surfactant.   The method according to claim 3, wherein a polyglycerin fatty acid ester is used as the nonionic surfactant.   The method in any one of Claims 1-4 which performs a 2nd process by heating the oyster fruit after performing a 1st process in weak alkaline aqueous solution.   The method according to any one of claims 1 to 5, wherein the enzyme used in the third step has a function of decomposing pectin.   The method according to any one of claims 1 to 6, wherein the fourth step removes at least the pericarp of the oyster fruit by rubbing the oyster fruit after running the third step in running water. .