JP3617042B2 - Oyster Fruit Peeling Method, Peeled Fruit, and Packaged Peeled Fruit - Google Patents

Description

  The present invention relates to a method for peeling oyster fruit without using a blade, a peeled fruit obtained by this method, and a packaged peeled fruit.

Oysters are fruits that have been widely eaten in Japan for a long time, but their consumption is mainly raw foods, and the processed products are limited to dried persimmons and antelope persimmons. In recent years, with the increase in production volume, new demands including development of new processed products have been demanded.
It is said that one of the factors hindering the expansion of oyster demand is its strong pericarp. In recent years, the tendency to consume “easy to peel and easy to eat” has become remarkable, and so-called “cut fruit”, which has been cut to a size that is easy to eat after removing skin and seeds, is expanding the market.

By the way, the technique described in the following patent document 1 is known regarding the peeling of oyster fruit.
JP-A-7-1332075;

  The oyster fruit skinning method disclosed in this publication is such that a rotationally driven needle is stabbed into the oyster fruit and rotated, and a knife is applied to the surface of the oyster fruit to peel the fruit skin. Thus, in the method using the blade, a large number of ridges of the cut surface appear on the surface of the peeled fruit, and the appearance of “peeled” is exhibited. Moreover, the loss of pulp accompanying peeling is large and the productivity is low. In addition, there is a problem that the inside of the pulp is damaged by the piercing of the needle body, and the softening of the pulp proceeds from that portion. Therefore, even though this peeling method can be applied to the production of dried koji and anpo koji, it is not suitable for cut fruits. In addition, the productivity is not so high when it is processed into dried potato and anpo rice cake. Under such circumstances, development of a technique for peeling oyster fruits in a large amount and labor-saving has been strongly demanded.

On the other hand, a method for peeling fruit using a high-temperature and high-pressure gas is described in Patent Document 2 below.
JP 59-192040 A;

In the method disclosed in the above publication, high pressure steam of 294 to 882 kPa is blown into a hermetic pressure resistant container containing oyster fruits, and the inside of the container is heated and pressurized. Then, after the predetermined time has elapsed, the inside of the sealed pressure-resistant container is rapidly returned to normal pressure. Then, due to a sudden pressure difference between the inside and outside of the oyster fruit, explosive boiling occurs inside the skin layer, the skin layer swells and peels from the pulp, and immediately after that, the entire skin layer bursts and leaves the pulp.
However, this skinning method requires a sealed pressure-resistant container that can withstand a pressure change between high pressure and normal pressure. Therefore, the equipment is serious and requires a great amount of construction cost, and sufficient attention must be paid to the operation. In addition, the persimmon fruit used in this peeling method has only a strong cortex so that the skin layer maintains its original shape even when heated and pressed, for example, only Fuyu persimmon is applied. By the way, in varieties with relatively weak cortex, such as early-born Tone, Tokuno Hakuin, etc., the skin layer is cracked when heated and pressurized, so the skin layer explosively boils even when atmospheric pressure drops due to pressure leakage from the wound. Most of the cortex remains attached to the pulp.

By the way, as shown in FIG. 4, the outer pericarp tissue of oysters is composed of four layers such as a cuticle, an epidermis, a subepidermis, and stone cells in order from the outside. Of these, the cuticle is particularly strong and plays an important role in protecting the pulp. The cuticle has a dense tissue and water repellency on the surface, whereas the outer skin structure inside the cuticle is relatively sparse.
The present inventors have further investigated the role of the outer skin structure including such cuticles, and after making the cuticles cracked or exfoliated to some extent, they were impregnated with an enzyme so that the inner outer skins were impregnated. It was inferred that the enzyme could penetrate into the tissue. In other words, pectin degrading enzymes can act on the cell space of the pericarp tissue to dissociate the adhesion between the cells that make up the tissue, thereby effectively peeling the oyster fruit without using a blade or the like. I thought it would be possible.

  On the other hand, many plants are said to possess inhibitors that inhibit the activity of pectin degrading enzymes in order to protect themselves from pectin degrading enzymes. Such pectin degrading enzyme activity inhibitors often have different chemical structures depending on the type of plant, but have been reported to be polymer compounds such as polyphosphates and glycoproteins (Y. Aharonowitz et al., Novel Microbial Products for Medicine and Agriculture, 1989, Society for Industrial Microbiology.). And for oysters, the chemical structure has not been identified, but it is thought to have similar inhibitors. If such an inhibitory factor remains in oyster fruit, it will adversely affect the peeling action of oyster fruit by pectin degrading enzymes.

  As a result of intensive studies based on such inferences, the present inventors have (1) inactivated pectin degrading enzyme activity inhibitory factors in oyster fruits by performing predetermined heat treatment on oyster fruits. In addition, at least cracks can be generated in the cuticle without affecting the characteristics of the pulp, and (2) at least the cracked oyster fruit is impregnated with pectin degrading enzyme, so Found that the enzyme permeates the pericarp tissue, and that the pericarp tissue can be disintegrated, and (3) the pericarp tissue disintegrated by the enzyme treatment can be easily removed by removal treatment by water flow, brush, hand washing, The present invention has been completed.

  That is, according to the present invention, the oyster fruit is heated by the heating means to inactivate the pectin degrading enzyme activity inhibitor contained in the oyster fruit, and at least cracks are formed in the cuticle of the oyster fruit. A heat treatment step for generating, an enzyme treatment step for impregnating the pericarp tissue of oyster fruit by impregnating the oyster fruit in which at least cracks have occurred in the cuticle by heating in the heat treatment step, and degrading the pericarp tissue of the oyster fruit; A peel method of oyster fruit, comprising a skin peel removing step of removing peel skin tissue decomposed by pectin degrading enzyme in the step to obtain peel skin fruit, peel skin fruit obtained by this method, and Packaged peeled fruit is provided.

  According to the method of the present invention, it is sufficient to inactivate the pectin degrading enzyme activity inhibitor and to carry out heat treatment to such an extent that only the cuticle is cracked or peeled off. It does not require a pressure vessel, can be easily heat-treated with simple equipment, and can be applied to oyster fruits of a relatively weak cortex. Then, since the enzyme treatment is performed in a state where the outer skin tissue other than the cuticle remains, the effect of the pectin degrading enzyme affects the outer skin tissue, but hardly affects the flesh. Therefore, the peeled fruit has a soft texture unique to oysters without softening of the pulp due to the enzyme treatment, and exhibits a rounded appearance in which the outer peel tissue is peeled off uniformly. By the way, if the flesh after removing the outer skin tissue with a blade is treated with pectin degrading enzyme, the progress of the enzyme reaction is uneven, the surface is partially eroded, and the outer skin tissue is evenly peeled off. A characteristic appearance cannot be obtained. In other words, the present invention can remove the pericarp tissue without using a cutting machine such as a blade, and can produce oyster peeled fruit in a state where it can be eaten. It becomes possible to do. Moreover, since the pulp is hardly taken away, the pulp yield is extremely high.

  The peeled fruit obtained by the above-mentioned production method has a good appearance, leaves a texture unique to oysters, and is suitably provided as a cut fruit that saves the trouble of peeling a hard skin when eating.

  If the peeled fruit is packaged in a sealed state with a synthetic resin film having a gas barrier property and then heated to a predetermined temperature, the pectin degrading enzyme is inactivated by heating after packaging to prevent subsequent softening. At the same time, the inside of the package can be sterilized. Further, since the synthetic resin film replaces the cuticle and shields the inside of the package from the outside to protect the pulp from mold and microorganisms, the storage stability can be improved.

  The oyster fruit to which the method of the present invention is applied is a fruit of a plant known by the scientific name of Diospyros kaki belonging to the family Oysteraceae, and it can be used for food, regardless of whether it is sweet potato or astringent. However, varieties such as early-born Tone Tone and Hiraketsu Mutsu are particularly preferred.

  The heat treatment step performed as a pretreatment of the enzyme treatment step according to the present invention has a function of inactivating the pectin degrading enzyme activity inhibitor in oyster fruit and causing cracks in the cuticle of oyster fruit. However, it is desirable that it is a process that can heat-treat the fruit surface in a short time. If cracks are generated over the entire surface of the cuticle by such a heat treatment step, the pectin degrading enzyme can be impregnated from the cracks into the outer skin structure inside the cuticle. However, as long as the heat treatment conditions are within a range that does not affect the hardness of the pulp, the conditions may cause cracks in the cuticles, and the cuticles may be peeled from or detached from the outer peel structure.

  Examples of the heating means in the heat treatment step include hot water, superheated steam, hot air, and the like. Among them, hot water is suitable for heating for a short time because it has a large sensible heat per capacity, and is easy to use. When such hot water is used, hot water from 80 ° C. to 100 ° C., more preferably from 95 ° C. to 100 ° C. is preferable. The amount ratio of oyster fruit to be added to hot water is desirably 50 to 100 L of hot water with respect to a ratio at which a decrease in water temperature is suppressed within 5 ° C., for example, 10 kg of oyster. The heat treatment time is preferably as short as possible in order to prevent softening of the pulp. For example, when the water temperature is 98 ° C., it is 30 seconds to 120 seconds, more preferably 60 seconds to 90 seconds. Inactivating the pectin degrading enzyme activity inhibiting factor is a tradeoff between the heating temperature and the heating time. For example, when hot water at 98 ° C. is used, the heating time is preferably 30 seconds or more. On the other hand, when superheated steam is used, since heating is the purpose, it is not necessary to perform the treatment in a high-pressure vessel, and it is sufficient to spray superheated steam on oyster fruits under normal pressure.

  The oyster fruit after the heat treatment can be quickly cooled to minimize degradation of the pulp quality. Although the embodiment of the oyster fruit can be cooled as long as the surface temperature of the oyster fruit can be lowered to 40 ° C. or less within 30 seconds, it is usually achieved by immersing the fruit in running water or ice water.

  The pectin degrading enzyme used in the enzyme treatment step of the present invention can be produced by microorganisms or synthesized by an enzyme that has an activity of acting on insoluble protopectin to break down plant tissues, so-called maceration activity. Any of those obtained may be used, and only one kind of enzyme may be used or two or more kinds may be used in combination.

  Such pectin degrading enzymes include protopectinases (Methods in Enzymology, 161, 335, 1988) produced by yeasts and yeast-related microorganisms such as Trichosporon penicillatum, Aspergillus awamori (Aspergillus awamori). ) Derived polygalacturonases (Biochem. Biophys. Biotech., 64, 1337 and 1729, 2000), polymethoxygalacturonases derived from Trichosporon penicillatum (FEBS Letters, 414, 439, 1997) Protopectinase-S (Methods in Enzymology, 161, 335, 1988) produced by the Tricospolone penicillatam SNO3 strain is particularly preferred.

  In the enzyme treatment step of the present invention, the pectin degrading enzyme can be used in either a liquid or solid form, but does not affect the enzyme action like water, buffer solution, preferably distilled water. It can be used as an enzyme-containing liquid obtained by dissolving an enzyme in a liquid. And, as an aspect of impregnating oyster fruit with pectin degrading enzyme, an aspect such as flowing an enzyme-containing liquid on the surface of oyster fruit, spraying, applying, or immersing oyster fruit in the enzyme-containing liquid Can be mentioned. For example, an oyster fruit in which the cuticle is partially peeled or cracked is immersed in an enzyme-containing aqueous solution at a temperature of 10 to 55 ° C., preferably 25 to 37 ° C., for a predetermined time, and is removed from the cracked or peeled portion of the cuticle. The pericarp tissue can be disrupted by infiltrating the enzyme into the pericarp tissue. In addition, when the enzyme-containing liquid is poured, sprayed or applied to the surface of oyster fruit, the oyster fruit is at a temperature of 10 to 55 ° C., preferably 25 to 37 ° C., while preventing moisture from evaporating for a predetermined time, The pericarp tissue can be disrupted by leaving it in the air and allowing the enzyme reaction to proceed. These treatment modes are more efficient than the case where they are continuously dipped, and since a dipping tank is not required, a specific place can be taken and the treatment place can be moved.

  The pectin-degrading enzyme described above depends on the enzyme and the type of target oyster fruit, but is usually used at a concentration of 100 to 500,000 U (international unit) per kg of oyster fruit, specifically 200 to 400,000 U. The enzyme-containing liquid is preferably prepared in such an amount that the enzyme concentration is within the above-mentioned range and all oyster fruits are immersed. Moreover, the solution prepared to the said density | concentration can be used also when flowing and spraying an enzyme containing liquid on an oyster fruit, and apply | coating.

  In addition, the impregnation procedure, the impregnation time, and the like are arbitrary as long as the pectin degrading enzyme can be impregnated in the outer skin tissue inside the cuticle. For example, the enzyme-containing liquid may be added to a container containing oyster fruit, or the oyster fruit may be added to a container containing the enzyme-containing liquid in advance. In addition, the impregnation procedure and the impregnation time are arbitrary when the enzyme-containing liquid is flowed down, sprayed and applied to oyster fruits. The enzyme treatment time for impregnating the pectin degrading enzyme is not particularly limited as described above, but it is usually 1 hour to 3 hours, preferably 90 to 120 minutes for industrial implementation.

  In the outer skin removal step of the present invention, the outer skin tissue after the enzyme treatment is removed from the fruit surface by the removing means. Such removal means is not particularly limited as long as it does not take time and does not damage the fruit surface after removal of the outer skin tissue, for example, rubbing by hand, rotating brush, etc. Examples of mechanical devices that combine the above are given. By the way, if the outer skin tissue is removed using running water, the enzyme will be removed and the flesh will not ripen. It is also possible to remove the pericarp tissue by wiping the fruit surface with hand in running water. When a rotating brush is used, the pericarp tissue can be removed with a very small pressing force, and the power cost is low.

The oyster peeled fruit obtained by the method of the present invention can be used as a food as it is. Further, the peeled fruit can be subjected to secondary processing to produce various foods such as jelly and sheep pods, or dried cocoons and anpo rice cakes.
When the food is used as it is, after the peeled fruit is immersed in an ascorbic acid aqueous solution or the like, the peeled fruit is packaged in a hermetically sealed manner with a synthetic resin film having a property of not allowing gas such as air to permeate, so-called gas barrier properties. Then, the packaged peeled fruit that has been hermetically packaged is heated to a predetermined temperature. The predetermined temperature is a temperature at which the used pectin degrading enzyme can be inactivated and microorganisms mixed in the package can be sterilized, and is about 60 ° C., for example. The temperature required for such heating varies depending on the heating time. For example, in the case of long-time heating, it may be about 50 ° C., but in the case of industrially desired short-time heating, it is preferably 85 ° C. or higher. Thus, the packaged peeled fruit after heating can be stored for several weeks by refrigerated storage, and can be distributed to the market as cut fruit.

EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated, the technical scope of this invention is not limited to these Examples.
Example 1.
One each of plain nucleus seedless oyster fruits, separately in 3 L of hot water at 60 ° C. (Example 1-1), 80 ° C. (Example 1-2), 100 ° C. (Example 1-3) Immersion and heat treatment for 30 seconds to 60 minutes, followed by quenching with running water. The hardness of the processed oyster fruit side part and fruit top part (the part opposite to the side) was measured with an intrusion type fruit hardness tester (one with a conical needle head mounted on a universal type manufactured by Kiyama Seisakusho). Moreover, the surface state of the cuticle of oyster fruit was visually determined, and a five-step cuticle peel score was assigned.

Comparative Example 1
About the same plain nucleus seedless oyster fruit used in Example 1, the hardness of the fruit side part and the fruit top part was measured as a blank without heat treatment.

  The oyster fruit hardness of Example 1 and Comparative Example 1 obtained as described above is shown in Table 1 below, and the peel peel score according to Example 1 is shown in Table 2 below.

The numerical values in Table 2 are five-step cuticle peeling scores evaluated according to the state of cuticles after heat treatment, and each shows an average value of a plurality of samples.
The content of “skin peel score” in Table 2 is as follows.
1: No change.
2: Wrinkles are generated on the surface.
3; A fine crack has occurred.
4; A large crack has occurred.
5: The cuticle is peeled off.

  As shown in Table 1 and Table 2, in the 60 ° C. hot water treatment section, even when immersed in hot water for 60 minutes, the cuticle was hardly damaged. Even at the 80 ° C. treatment, peeling of the cuticle was insufficient. In the 100 ° C. treatment group, peeling of the cuticle was remarkable, and peeling of the cuticle more than in the case of treatment at 80 ° C. for 10 minutes was observed even in the treatment for 30 seconds (0.5 minutes). In the 100 ° C. treatment group, the peeling of the cuticle progressed with the lapse of the treatment time of 1 minute and 2 minutes. For reference, FIG. 1 shows a state of oyster fruit 1A that has been heat-treated at 100 ° C. for 1 minute. The outer skin structure 3A covering the surface of the pulp 4 is exposed at the cracked portion except for the outer skin 2 with a fine crack in the cuticle 2. A part of the cuticle 2 is peeled off from the outer skin tissue 3A. On the other hand, regarding the fruit hardness, the hardness decreases gradually as the hot water immersion time increases, and the hardness decreases as the temperature increases.

  From the above results, it is considered that heat treatment at as high a temperature as possible is important in order to efficiently cause cracking and peeling of the cuticle. Incidentally, it was shown that when treated with hot water at 100 ° C. for 1 minute, softening of the pulp is also minimized.

Example 2
According to the method described in Example 1-3, heat treatment at 100 ° C. determined to be effective for cracking and peeling of the cuticle was performed for 30 seconds (Example 2-1) and 60 seconds (Example), respectively. 2-2), for 120 seconds (Example 2-3), the pectine-degrading enzyme Pectinase-GODO (Trichosporon penicillatum) pectin degrading enzyme, joint liquor purification ) Was used to test the decay of the outer pericarp tissue.
A 0.1 wt% aqueous solution of the enzyme was prepared, and 650 mL thereof was placed in a 1000 mL beaker. The enzyme aqueous solution was preheated in a constant temperature bath set at 37 ° C. When the aqueous enzyme solution reached 37 ° C., two oyster fruits from which the cuticles were partially peeled in advance by heat treatment were immersed in the aqueous enzyme solution. The beaker was transferred to a thermostat and kept at 37 ° C., and oyster fruit was taken out after a predetermined time (30 minutes, 60 minutes, 90 minutes, 180 minutes). The oyster fruit treated with the enzyme was lightly rubbed by hand in running water to remove the disintegrated pericarp tissue. The remaining state of the pericarp tissue was judged visually and evaluated by a five-step peel score.

Example 3 FIG.
Heated oysters were used in the same manner as in Example 2 except that maceroteam A (Rhizopus genus pectin degrading enzyme, manufactured by Yakult Yakuhin Kogyo Co., Ltd.) was used instead of Pectinase-GODO. The fruit was enzyme treated.

Comparative Example 2
The heated oyster fruit was enzymatically treated in the same manner as in Example 2, except that purified papain F (papaya-derived proteolytic enzyme, manufactured by Asahi Breweries), which is a non-pectinase enzyme, was used instead of Pectinase-GODO.

Comparative Example 3
Enzymatic treatment of cooked oyster fruits in the same manner as in Example 2 except that Sumiteam AC (cellulolytic enzyme derived from Aspergillus niger, manufactured by Shin Nippon Chemical Industry), a non-pectinase enzyme, was used instead of Pectinase-GODO. did.

Comparative Example 4
Enzymatic treatment of cooked oyster fruit in the same manner as in Example 2 except that Sumiteam C (Trichoderma-derived cellulose-degrading enzyme, manufactured by Shin Nippon Chemical Industry), a non-pectinase enzyme, was used instead of Pectinase-GODO. did.

Comparative Example 5
Oyster fruits were treated with enzymes in the same manner as in Example 2, except that plain nuclear seedless oyster fruits that were not heat-treated were used.

The numerical values in Tables 3 and 4 are five-step peeling scores evaluated by the state of the pericarp tissue after the enzyme treatment, and show the average values of a plurality of samples.
The contents of the “peeling score” in Tables 3 and 4 are as follows.
1: No change.
2; The cuticle can be partially peeled off.
3; The pericarp tissue is partially destroyed.
4: The pericarp tissue is largely collapsed.
5: The pericarp tissue is completely disintegrated.

For Pectinase-GODO (Example 2) and maceroteam A (Example 3) having maceration activity, the pericarp tissue of the oyster fruit can be decomposed and disintegrated. It could be removed simply by rubbing by hand. In particular, Pectinase-GODO had a greater skinning effect even when heat-treated at a lower temperature than Macero Team A.
In contrast, when a non-pectinase-based enzyme agent having no pectin degradation activity is used, such as purified papain F (Comparative Example 2), Sumiteam AC (Comparative Example 3), and Sumiteam C (Comparative Example 4). Has little effect on the state of the pericarp tissue. In addition, as in Comparative Example 5, oyster fruits that had not been heat-treated and were harvested were not affected by even the cuticles even when treated with Pectinase-GODO, and the surface state did not change.

  For reference, the peel peel obtained in Example 2-2 by immersing an oyster fruit heat-treated at 100 ° C. for 60 seconds in a 0.1 wt% aqueous solution of Pectinase-GODO for 90 minutes and then rubbing by hand in running water. The fruit is shown in FIG. In the peeled fruit 1B shown in the figure, the outer skin structure is peeled and removed, the surface 3B of the pulp 4 is exposed over the entire surface, and the whole appearance is rounded. The surface 3B has a fresh appearance, and the texture is very similar to the surface of a peach peeled without using a knife. Also, the surface 3B is somewhat soft and palatable, so it is suitable as a cut fruit.

Example 4
For the Pectinase-GODO used in Example 2, further detailed enzyme treatment conditions were examined. By using the plain nucleus solid fruit pre-treated under the optimized heat treatment conditions (100 ° C., 1 minute) and exfoliated the keratin by the method described in Example 1-3, a disintegration test of the outer pericarp tissue was performed. went. 0.001 wt%, 0.01 wt%, and 0.1 wt% aqueous solutions of pectinase-GODO were prepared, and 650 mL of each enzyme aqueous solution was placed in a 1000 mL beaker. The enzyme aqueous solution was preheated in a constant temperature bath set at 37 ° C. When the enzyme aqueous solution reached 37 ° C., two fruits from which the cuticle was peeled in advance by heat treatment were immersed in the enzyme aqueous solution. The beaker was transferred to a thermostat and kept at 37 ° C., and oyster fruit was taken out after a predetermined time (30 minutes, 60 minutes, 90 minutes, 120 minutes, 180 minutes). The oyster fruit treated with the enzyme was lightly rubbed by hand in running water to remove the disintegrated pericarp tissue. The remaining state of the pericarp tissue was judged visually and evaluated by a five-step peel score.

Embodiment 5 FIG.
The oyster fruit was enzymatically treated in the same manner as in Example 4 except that maceroteam A was used instead of Pectinase-GODO in Example 4 and oyster fruit heat-treated at 100 ° C. for 2 minutes was used.

  The results of Example 4 and Example 5 are shown in Table 5 below.

The numerical values in Table 5 are five-step peel scores evaluated according to the state of the pericarp tissue after enzyme treatment, and show the average values of a plurality of samples.
The contents of the “peeling score” in Table 5 are as follows.
1: No change.
2; The cuticle can be partially peeled off.
3; The pericarp tissue is partially destroyed.
4: The pericarp tissue is largely collapsed.
5: The pericarp tissue is completely disintegrated.

  As shown in Table 5, with regard to maceroteam A, it was possible to obtain a skinning effect by setting the enzyme concentration to 0.1 wt% or more and the enzyme treatment time to 90 minutes or more. On the other hand, regarding Pectinase-GODO, a particularly excellent peeling effect is obtained by setting the enzyme concentration to 0.01 wt% or more and the enzyme treatment time to 90 minutes or more. That is, Pectinase-GODO had a greater skinning effect even with a lower concentration of enzyme treatment than maceroteam A.

Example 6
Here, the example which manufactures the sealed packaging goods of peeled fruit is shown. That is, peeled fruit was obtained in the same manner as in Example 4 except that the oyster fruit heat-treated in Example 1-3 was subjected to enzyme treatment in Example 4-3 for 90 minutes. The oyster peeled fruit thus obtained was cut with a knife in a cross shape and immersed in a 1 wt% L-ascorbic acid solution for 15 minutes. After that, put the peeled fruit in a polyethylene bag with a film thickness of 50 μm, deaerate the inside of the bag using a commercial desktop vacuum sealer (Sharp Co., Ltd. SQ-202 type), and seal and wrap it with heat seal. Obtained.
The packaged peeled fruit was kept in boiling water for 1 minute to sterilize the inner surface of the bag and the peeled fruit surface, and inactivate the pectin degrading enzyme that may remain on the fruit surface. The packaged peeled fruit thus heated was allowed to cool and then stored at 5 ° C., and even after about 10 days after the treatment, no change in color, change in fruit hardness, and growth of microorganisms were observed, and as a cut fruit Of good quality.

Example 7
By the way, how the cracks of the cuticle are caused by the heat treatment varies depending on the ripening state and storage state of the oyster fruit. For example, even when heat treatment is performed using hot water at 100 ° C. as described above, if the heating time is less than 30 seconds, the cuticle is cracked, and then enzyme treatment is performed. Even then, there was a case where the outer skin tissue did not collapse.
That is, plain-nucleated unripe fruit, (1) in the appropriate ripening period (suitable fruit, Example 7-1), (2) collected in the appropriate ripening period and wrapped in polyethylene film for 1 month at 5 ° C About 3 sections of stored products (stored fruits, Example 7-2), (3) fully-ripened products (completely-ripened fruits, Example 7-3), each oyster fruit, 3 L of hot water at 100 ° C It was immersed separately in, held for 10 seconds, 30 seconds, and 60 seconds, respectively, and then quenched with running water. About the state of the cuticle of the oyster fruit after a heat processing, it evaluated by the five-step cuticle peeling score. These evaluation results are shown in Table 6 below. The contents (1-5) of the “skin peel score” in Table 6 are the same as the contents of the peel peel score shown in Table 2.
In addition, these oyster fruits after the heat treatment were immersed in a 0.1 wt% aqueous solution of Pectinase-GODO maintained at 37 ° C. as described above, held for 2 hours, and then oysters were removed to remove the outer skin tissue. The fruit was lightly rubbed by hand in running water. The remaining state of the pericarp tissue was judged visually and evaluated by a five-step peel score. The contents (1 to 5) of the “peeling score” in Table 6 are the same as the contents of the skinning score shown in Table 5.

  As shown in Table 6, even when a heat treatment (10 seconds) of less than 30 seconds is applied to a suitable ripe fruit harvested in the appropriate maturity period, the cuticle state does not crack and the cuticle state changes before and after the treatment. (Example 7-1). On the other hand, in the oyster fruit (Example 7-2) and the fully ripe oyster fruit (Example 7-3) which were harvested in a suitable ripening period and stored at a low temperature for a certain period, heat treatment (10 seconds) less than 30 seconds. Even so, the cuticles can be cracked. However, even if the oyster fruit (Example 7-2, Example 7-3) cracked by such heat treatment for less than 30 seconds was treated with an enzyme, the outer skin structure did not collapse. This is considered to be because an inhibitory factor that inhibits the activity of pectin degrading enzyme exists in oyster fruit, and this inhibitory factor could not be inactivated under the aforementioned heat treatment conditions (100 ° C., less than 30 seconds).

Example 8 FIG.
Therefore, in this example, a confirmation test was carried out for “the presence of an enzyme activity inhibitor contained in oyster fruit and inactivation of the enzyme activity inhibitor by heat treatment”.
First, peel off plain oyster fruit with a knife, add 50 mL of 100 mM acetic acid milder solution (pH 5.5) to the peeled skin (16.2 g), and grind it with a Polytron homogenizer while cooling with water. did. This ground product was centrifuged at 13000 rpm and 4 ° C. for 40 minutes to obtain a supernatant. The supernatant was transferred to a dialysis tube (Wako Pure Chemicals, Dialysis membrane 8) and dialyzed against 20 mM acetate buffer (pH 5.5), and the liquid remaining in the tube was used as the pericarp extract. . This pericarp extract is a high molecular component containing protein. The pectin degrading enzyme activity was measured by quantifying galacturonic acid produced by an enzymatic reaction using polygalacturonic acid potassium salt (manufactured by Sigma Chemical) as a reducing sugar by the Somogyi-Nelson method. In this case, the Pectinase-GODO powder was dissolved in 20 mM acetate buffer (pH 5.5) so as to be 0.001 wt% to obtain an enzyme solution. Moreover, polygalacturonic acid potassium salt was dissolved in 20 mM acetate buffer (pH 5.5) so as to be 0.2 wt% to obtain a substrate solution. After adding 50 μL of the enzyme solution and 50 μL of the fruit juice extract to 400 μL of this substrate solution and reacting at 37 ° C. for 30 minutes, the amount of reducing sugar in the reaction solution was quantified by using the Somogyi-Nelson method with galacturonic acid as a standard, The enzyme activity U of the reaction solution was calculated assuming that the enzyme activity releasing 1 μmol of galacturonic acid per minute was 1 U (unit) (Example 8-1). Further, in place of 50 μL of the peel extract in Example 8-1, this skin extract was used in Example 8- except that 50 μL of the heated peel extract obtained by heating in a boiling water bath for 30 minutes in advance was used. The enzyme activity U of the reaction solution was calculated in the same manner as in Example 1 (Example 8-2). As for the control (Comparative Example 6), Example 8-1 or the implementation was carried out except that 50 μL of 20 mM acetic acid buffer (pH 5.5) was used instead of 50 μL of the above-described peel extract or 50 μL of heated peel extract. The enzyme activity U of the reaction solution was calculated in the same manner as in Example 8-2. The measurement results are shown in Table 7 below and FIG.

  As shown in Table 7 and FIG. 3, in the reaction system of the substrate solution and the enzyme solution to which the peel extract was added (Example 8-1 and B in FIG. 3), the activity of the pectin degrading enzyme was Compared with the control (Comparative Example 6, A in FIG. 3), it was suppressed to about 1/4. In addition, in the reaction system of the substrate solution and the enzyme solution to which the heated skin extract was added (Example 8-2, C in FIG. 3), the activity of the pectin degrading enzyme remained at about 2/3 of the control. ing. That is, these results indicate that an inhibitory factor that inhibits the activity of pectin degrading enzyme exists in the pericarp of oyster fruit, and that the inhibitory factor is inactivated by heat treatment.

Example 9
Next, we examined the necessity of heat treatment on the peeled state using a large number of plain oysters. As the oyster fruit in the heating section, one that had been subjected to heat treatment at 100 ° C. for 60 seconds to damage the cuticle (Example 9 (corresponding to Example 2-2)) was used. In addition, as oyster fruits in the non-heated area, instead of heat treatment, (1) one in which the cuticle was partially damaged using a metal brush (Comparative Example 7), (2) the corner using sandpaper What completely removed the skin (Comparative Example 8) was used. Each of the oyster fruits treated as described above was immersed in a 0.1 wt% aqueous solution of Pectinase-GODO and subjected to enzyme treatment in the same manner as in Example 2-2. After 3 hours of immersion, the oyster fruit was removed from the enzyme aqueous solution, and the surface of the oyster fruit was lightly rubbed by hand in running water. The remaining state of the outer pericarp fabric of oyster fruit was visually judged and evaluated by a five-step peel score. The evaluation results are shown in Table 8 below. The contents (1 to 5) of the “skinning score” in Table 8 are the same as the contents of the skinning score shown in Table 5.

  As can be seen from Table 8, when the enzyme treatment was performed after the predetermined heat treatment (Example 9), the outer skin tissue was well disintegrated, whereas the cuticle was mechanically not affected by the heat treatment. Neither the partially damaged one (Comparative Example 7) nor the one from which the cuticle was completely removed (Comparative Example 8) caused disintegration of the pericarp tissue by the enzyme treatment. That is, as described above, there is an inhibitor of pectin degrading enzyme activity in oyster fruits as described above, and in oyster fruits in the heating zone (Example 9), the keratin skin is damaged and the inhibitory factor is heated. This confirms that inactivation has occurred.

Example 10
In the impregnation mode of the enzyme treatment in Examples 1 to 7 and Example 9, the mode of continuously immersing in the aqueous enzyme solution was taken. Therefore, in this Example 10, for plain-nucleated unripe fruit that was heat-treated under the heat-treatment conditions (100 ° C., 1 minute) optimized by the method described in Example 1-3 to peel off the cuticle, Enzyme treatment was performed in an impregnation mode different from “continuous soaking” of No. 1, and the decay of the pericarp tissue of oyster fruits was evaluated.
That is, a 0.1 wt% aqueous solution of Pectinase-GODO was prepared, and 650 mL of the enzyme aqueous solution was put in a 1000 mL beaker. The enzyme aqueous solution was preheated in a constant temperature bath set at 37 ° C. When the enzyme aqueous solution reached 37 ° C., two oyster fruits in each group were subjected to enzyme treatment in an impregnation manner of each test group described below with respect to the oyster fruit from which the cuticle was peeled in advance by heat treatment.

Test group (1): After oyster fruits were immersed in the enzyme aqueous solution for about 10 seconds, they were immediately removed from the enzyme aqueous solution. One oyster fruit was placed in a sealed container (Example 10-1), and the other oyster fruit was an open container ( In Example 10-2), each was held at 37 ° C. for 2 hours.
Test group (2): A glass spray bottle containing an enzyme aqueous solution, and about 1.5 mL of the enzyme aqueous solution per oyster fruit was uniformly sprayed on the surface of the oyster fruit, and one was a sealed container (Example 10). -3), the other was placed in an open container (Example 10-4), and each was held at 37 ° C. for 2 hours.
Test group (3): Place oyster fruits with the top of the fruit on top, drop about 2 mL of enzyme solution per oyster fruit from the top of the fruit and allow it to flow evenly onto the surface of the oyster, then one is sealed The container (Example 10-5) and the other were placed in an open container (Example 10-6), and each was held at 37 ° C. for 2 hours.
Test group (4): Oyster fruits were immersed in an aqueous enzyme solution and kept at 37 ° C. for 2 hours in a state where the immersion was continued (Example 4-3).
After the enzyme treatment in the test sections (1) to (4), each persimmon fruit was gently rubbed in the running water by hand to remove the disintegrated outer skin tissue. The remaining state of the pericarp tissue was judged visually and evaluated by a five-step peel score. These evaluation results are shown in Table 9 below. The contents (1 to 5) of the “peeling score” in Table 9 are the same as the contents of the peeling score shown in Table 5.

  As shown in Table 9, even when the enzyme reaction was performed in any of the impregnation modes of the test sections (1) to (3), the same was true when the oyster fruit was put in a sealed container and stored at 37 ° C. When the immersion in the enzyme aqueous solution was continued for a period of time (2 hours) (study group (4)) (score 5), disintegration of the pericarp tissue was observed, and the skin could be peeled almost completely. On the other hand, when the fruit is put in an open container and kept at 37 ° C., the surface of the outer skin tissue is dried, and even after a predetermined time (2 hours in this example) has elapsed, the outer skin tissue is partially disintegrated. (Score 2). From the above results, the enzyme reaction does not necessarily require the oyster fruit to be immersed in the enzyme solution, a certain amount of the enzyme solution is spread on the surface of the heat-treated oyster fruit, and the oyster fruit It became clear that the pericarp tissue could be destroyed if the evaporation of moisture from the surface could be prevented.

Example 11
As in Examples 10-1 and 10-2 described above, the storage temperature conditions in the case of taking out from the enzyme aqueous solution after storage and storing it were examined in further detail.
Pectinase-GODO prepared according to the above-mentioned Examples 10-1 and 10-2 was prepared as a plain-nucleated unripe fruit with the cuticle peeled off at 100 ° C. for 1 minute by the method described in Example 1-3. Was immersed in a 0.1 wt% aqueous solution and held for about 10 seconds, and then immediately removed from the aqueous enzyme solution. A large number of oyster fruits treated in this way are divided into 10 test sections, each of which is a sealed container (Examples 11-1, 11-3, 11-5, 11-7, 11-9) and an open container (Examples). 11-2, 11-4, 11-6, 11-8, 11-10) and 10 ° C. (Examples 11-1 and 11-2) and 15 ° C. (Examples 11-3 and 11-4). ), 20 ° C. (Examples 11-5, 11-6), 25 ° C. (Examples 11-7, 11-8), and 30 ° C. (Examples 11-9, 11-10). After a predetermined time (4 hours, 6 hours, 24 hours), the oyster fruit was gently rubbed in running water by hand to remove the disintegrated outer skin tissue. The remaining state of the pericarp tissue was judged visually and evaluated by a five-step peel score. These evaluation results are shown in Table 10 below. The contents (1 to 5) of the “skinning score” in Table 10 are the same as the contents of the skinning score shown in Table 5. In the table, “-” marks (Examples 11-7 and 11-9) indicate that the highest score of the peeled score was obtained after 4 hours, and the subsequent evaluation was omitted.

As shown in Table 10, in the treatment time (storage time) of 4 hours, the outer skin tissue was disintegrated and peeled cleanly, which was put in a sealed container at 25 ° C. and 30 ° C. (Examples) 11-7, 11-9) only. In the temperature group of 20 ° C. or lower, since the evaporation of moisture from the surface of the oyster fruit is less than in the group of 20 ° C. or higher, the progress of the tissue collapse is slightly recognized. Among them, in the 10 ° C. area, although moisture was kept on the surface of the oyster fruit, the enzyme reaction did not seem to proceed sufficiently due to the low temperature. And if it accommodates in the airtight container, the enzyme reaction will progress with progress of time, and an outer skin tissue will collapse | disintegrate in any temperature zone of 10 degreeC, 15 degreeC, and 20 degreeC after 24 hours. It can be peeled cleanly.
From the above results, if the oyster fruit surface is not dried (in a closed container) and stored at a temperature of 25 ° C. or higher, the enzymatic reaction proceeds efficiently, and the pericarp tissue is disintegrated within 4 hours to peel the skin. I understand that I can do it. Of course, it is shown that if the storage time is further increased, the enzyme reaction proceeds sufficiently even at a low temperature of 10 to 20 ° C. On the other hand, when stored in an open container, the higher the storage temperature, the easier it is for the pericarp to dry.

It is a top view including the partial cross section which shows the oyster fruit after the heat processing which concerns on the Example of this invention. It is a top view including the partial cross section which shows the peeled fruit obtained by the enzyme process which concerns on the Example of this invention. It is a graph which shows the inhibitory effect of the pectin degrading enzyme activity based on the Example of this invention. It is a section lineblock diagram showing the pericarp of a common oyster fruit.

Explanation of symbols

1A Oyster fruit 1B Peeled fruit 2 Cuticle 3A Outer skin tissue 3B Surface 4 Fruit

Claims (3)

A heating process step of heating oyster fruit by a heating means to inactivate a pectin degrading enzyme activity inhibitor contained in oyster fruit, and causing at least cracks in the cuticle of oyster fruit, and the heating An oyster fruit having at least cracks in the cuticle due to heating in the treatment process is impregnated with a pectin degrading enzyme to degrade the pericarp tissue of the oyster fruit, and is decomposed by the pectin degrading enzyme in the enzyme treatment process. A method for peeling oyster fruit, comprising: removing a peeled skin tissue by a removing means to obtain peeled fruit. A peeled fruit obtained by the method for peeling an oyster fruit according to claim 1. A packaged peeled fruit obtained by packaging the peeled fruit according to claim 2 in a sealed manner with a synthetic resin film having a gas barrier property, and then heating the sealed peeled fruit to a predetermined temperature.