JP2013252058A - Method of manufacturing frozen fruit and frozen fruit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of manufacturing frozen fruit, which can reduce the loss of time required to freeze a fruit, and a frozen fruit.SOLUTION: A method of manufacturing frozen fruit includes setting freezing time according to the characteristics of a fruit, dipping the fruit in an antifreeze solution for the set freezing time to freeze the fruit, and preserving the frozen fruit in a refrigerator.

Description

  The present invention relates to a method for producing frozen fruit and a frozen fruit.

  As a method for preserving foods such as meat, fish and fruits, it is common practice to place these foods in a freezer set at −30 ° C. to freeze them and store them in this refrigerator. However, in the method (air blast method) in which the air in the freezer is cooled and sprayed on the food for freezing (air blast method), there is a problem that relatively large ice crystals are generated in the food during freezing, and the freshness, umami, etc. deteriorate.

  Foods have a maximum ice crystal formation temperature range in the range of -1 ° C to -5 ° C. In the freezing process, the water in the food crystallizes when passing through the maximum ice crystal generation temperature zone, and the grown crystals damage the food cells and fibers. If the cells or fibers of the food are damaged, drip is generated when the food is thawed, and the taste of the food deteriorates. The longer the time for passing through the maximum ice crystal generation temperature zone (slow freezing), the greater the damage to food cells and fibers.

  In Patent Document 1, an air cooler is provided above an endless conveyor that moves in the apparatus in the horizontal direction and conveys the object to be frozen, and the cool air from the air cooler is perpendicular to the traveling direction of the conveyor. The partition body of the continuous freezing device configured to be sprayed to the object to be frozen on the conveyor through the gaps of a number of partition bodies spanned across the width of the device in a desired interval is constituted by a column. A continuous freezing apparatus is disclosed in which the partition is provided such that the longitudinal direction is horizontal and the upper and lower surfaces are neither horizontal.

  On the other hand, there is a method (brine method) in which the food is immersed in an antifreeze solution and frozen in order to pass the maximum ice crystal generation temperature zone in a short time and suppress damage to food cells and fibers.

  In Patent Document 2, biological tissues such as meat and fish are directly immersed in an antifreeze liquid cooled to −6 ° C. to −79 ° C., or put in a package and cooled to −6 ° C. to −150 ° C. A method of freezing biological tissue that is immersed and rapidly frozen is disclosed.

JP-A-8-256747 Japanese Patent Publication No. 7-8222

  In general, in the production of frozen fruits using an antifreeze, the frozen fruits are taken out of the antifreeze and moved to another storage location (for example, a freezer) and stored frozen. However, it is difficult to grasp the time required for the step of freezing the fruit (the freezing step) (the time for immersing in the antifreeze solution), and there has been a problem that more time is required for the freezing step. The loss of time required for the freezing process has resulted in a decrease in productivity in the production of frozen fruits.

  Then, an object of this invention is to provide the manufacturing method and frozen fruit of the frozen fruit which can suppress the loss of the time required to freeze a fruit.

  As a result of earnest research to achieve the above object, the present inventors have found that when a fruit is immersed in an antifreeze and frozen, the freezing time can be obtained by grasping the characteristics of the fruit. The invention has been completed. Note that “soaking the fruit in the antifreeze” is not limited to the state where the entire fruit is covered with the antifreeze liquid, but a part of the fruit that protrudes from the antifreeze liquid as long as it does not hinder the freezing of the fruit. Including floating in antifreeze).

  The first feature of the present invention is that the freezing time is set according to the characteristics of the fruit, the set freezing time, the fruit is immersed in antifreeze and frozen, and the frozen fruit is put in a freezer. It exists in the manufacturing method of the frozen fruit to preserve | save.

  Preferably, the fruit property is the distance to the center of the fruit. Thereby, compared with the case where this structure is not provided, the freezing time is set easily.

  Preferably, the fruit is packaged before being immersed in the antifreeze solution, and the packed fruit is immersed in the antifreeze solution and frozen. This eliminates the trouble of packaging the fruit while preventing the fruit from coming into contact with the antifreeze.

  Preferably, the fruit is a mandarin. Thereby, the loss of time required for freezing the fruit which circulates widely is suppressed.

  Preferably, the mandarin orange whose size is divided based on the diameter of the fruit is set with a freezing time according to the size division. Thereby, the loss of time required for freezing the fruit which circulates more widely is suppressed.

  Preferably, the fruit property is the thickness of the fruit peel. Thereby, compared with the case where this structure is not provided, freezing time is set more effectively.

  The second feature of the present invention resides in a frozen fruit produced by any of the above production methods.

  According to the present invention, loss of time required for freezing fruits can be suppressed.

It is a flowchart of the manufacturing process of the frozen fruit which concerns on embodiment of this invention. It is a measurement result of the temperature change with respect to time of a plurality of citrus fruits. It is a measurement result of the temperature change with respect to time of a plurality of fruits. This is a measurement result of the distance to the center of a plurality of fruits and the time required for the temperature of the center to reach −5 ° C. This is a measurement result of the thickness of the peel of a plurality of fruits and the time required for the center temperature to reach −5 ° C.

In the present invention, “fruit” refers to fruits considered to be fruits in normal eating habits in addition to those harvested from woody plants (fruity vegetables: for example, “melon”, “watermelon”, “strawberry” Etc.).
Specific examples of the fruit include deciduous fruit trees, evergreen fruit trees, and tropical fruit trees.

  Deciduous fruit trees include pomegranates such as carin, pear, and apple, nuclear fruits such as American cherry, apricot, ume, cherry, plum and peach, shell fruit such as chestnut and walnut, or akebi, oyster, cassis, Examples include grapes and kiwifruit.

Examples of evergreen fruit trees include citrus fruits of the mandarin family, citrus genus, kumquat genus, and olives and loquat.
Citrus genus includes oranges such as Satsuma mandarin, kisumi mandarin, mandarin orange and ponkan, oranges such as Valencia orange, navel orange and blood orange, grapefruits such as grapefruit and orangero, natsumkan, hassaku, hyuganatsu, and dekopon. Tangos such as dango and agrifruit and tongues such as Iyokan and Tankan.
Examples of the genus Kumquat include marmi kumquat and fuchsia kumquat.

  Tropical fruit trees include mallows such as cacao and durian, papayas such as papaya, pineapples such as pineapples, bananas such as bananas, mangoes such as vanillaceae, mangosteens such as hypericaceae, acerola and other quintranosaceae, avocados A camphoraceae such as.

Next, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 shows a flowchart of a process for producing a frozen fruit according to an embodiment of the present invention.

In step 10 (S10), a pretreatment process is performed.
First, the fruit is washed, and the stickers and the like are removed as necessary. After washing, the water adhering to the fruit surface is removed by blowing air (air drying). By removing the moisture adhering to the fruit surface by washing, it is possible to prevent excess moisture from being included in the packaging in the subsequent packaging step (S20). Moreover, when a packaging process (S20) is abbreviate | omitted, it is suppressed that the antifreeze liquid used in a subsequent freezing process (S30) is diluted.

In step 20 (S20), a packaging process is performed.
The fruit is wrapped with a thermoplastic film such as polyethylene, and the inside is degassed and then sealed. The deaeration preferably removes air in the package as much as possible without causing excessive pressure to the fruit. Thereby, the efficiency which freezes a fruit improves in the following freezing process (S30), suppressing damage to a fruit. If the air in the package is removed under reduced pressure, such as evacuation, the fruit may be damaged or broken.
By packaging the fruit in the packaging step (S20), the trouble of subsequent packaging processing is omitted, and convenience in distribution is improved. Further, the packaging is not limited to sealed packaging, and a plurality of fruits may be packaged by a net-like member (net).
In addition, after a packaging process (S20) is abbreviate | omitted and a pre-processing process (S10) is performed, you may make it perform a freezing process (S30).

In step 30 (S30), a freezing process is performed.
Immerse the fruit in antifreeze and freeze the fruit to the inside. In the freezing step (S30), the center temperature of the fruit is set to −5 ° C. or lower, for example. If the center temperature of the fruit is -5 ° C, it can be treated as frozen. Further, from a practical viewpoint, the fruit may be frozen until the center of the fruit reaches −10 ° C.
If the temperature of the antifreeze is too high, the temperature at which the fruit is frozen becomes slow. On the other hand, if the temperature of the antifreeze is too low, the outside of the fruit is frozen rapidly, and cracks occur when the inside is frozen. For this reason, the temperature of the antifreeze is preferably -10 ° C to -50 ° C, more preferably -20 ° C to -40 ° C, and further preferably -25 ° C to -35 ° C.

  The time for which the fruit is immersed in the antifreeze is set according to the characteristics of the fruit. For example, in the freezing step (S30), a refrigeration apparatus that includes a timer for measuring time and moves the fruit from the antifreeze when a set time has elapsed is used. The movement of the fruit from the antifreeze liquid is performed, for example, by immersing the fruit in a basket-like container and immersing the fruit in the antifreeze liquid and pulling up the container. It should be noted that the movement of the fruit from the antifreeze may be performed automatically after a set time has elapsed, or may be performed manually.

  As the antifreeze, an alcohol antifreeze such as ethyl alcohol or propyl alcohol, an antifreeze containing propylene glycol, a sodium chloride aqueous solution, a potassium chloride aqueous solution, or the like is used. From the viewpoint of edible safety and practical use, it is preferable to use ethyl alcohol as the antifreeze. When ethyl alcohol is used as the antifreeze, the influence on the taste and odor of fruits that have not been subjected to the packaging step (S20) (unsealed fruits) is suppressed.

In step 40 (S40), a frozen storage process is performed.
The fruit frozen in the freezing step (S30) is moved from the antifreeze and stored frozen. Specifically, the frozen fruit is moved to a freezer set at, for example, −30 ° C., and stored in this freezer while maintaining the frozen state.
A general-purpose thing is used as a freezer, for example, the thing of the structure which cools the air in a warehouse with a heat exchanger is mentioned.

Next, the relationship between the characteristics of fruits and the freezing time will be described.
EXAMPLES Hereinafter, although an Example is described, this invention is not limited to these Examples.

<Example A>
Multiple fruits ("Grapefruit" which is a citrus fruit, "Red sweet summer (Rutaceae)", "Navel orange (Navel)", "Valencia orange (Orange)", "Mineola" and "Mikan", and "Melon" ], "Kiwi fruit (kiwi)" and "grape") were frozen, and the temperature change with time was measured. The appearance of the fruit after thawing was observed.

A “liquid freezer (manufactured by Technican Co., Ltd.)” was used as the refrigeration apparatus. As the antifreeze, ethyl alcohol was prepared in a 126 liter liquid tank and stirred with an agitator, and the temperature was set to -30 ° C. Fruits stored overnight in a refrigerator (−4 ° C.) were immersed in this antifreeze solution, and the temperature was measured every time.
As the thermometer, "Grapefruit", "Red sweet summer", "Navel", "Orange", "Mineola", and "Mikan", for these, "Digital thermometer CENTER309 (CENTER THECNOLOGY)" is used, Melon "," Kiwi ", and" Grape "For these," Center thermometer AD-5624 (manufactured by A & D Co., Ltd.) "was used, and sensors were arranged to measure the temperature of the fruit center. .

(grapefruit)
Fig.2 (a) shows the measurement result of a grapefruit.
In grapefruit, the temperature rose slightly immediately after being immersed in the antifreeze, then dropped relatively quickly to 2 ° C, and then dropped at a constant rate.

(Red sweet summer)
FIG.2 (b) shows the measurement result of red sweet summer.
In the red sweet summer, the temperature rose slightly after being immersed in the antifreeze solution, then became constant at around 3 ° C to 2 ° C for about 10 minutes, and then the temperature dropped. After that, it became constant for about 30 minutes around 0 ° C to -1 ° C, and then the temperature dropped relatively quickly.

(Navel)
FIG. 2C shows the measurement result of navel.
In Navel, the temperature rose slightly after immersion in the antifreeze and then decreased to 1 ° C. And it became constant for about 25 minutes around 1 ° C to 0 ° C, and then the temperature dropped relatively quickly.

(Orange)
FIG.2 (d) shows the measurement result of orange.
For orange, the temperature rose slightly after immersion in the antifreeze and then decreased to -1 ° C. And it became constant for about 30 minutes around -1 ° C to -2 ° C, and then the temperature dropped relatively quickly.

(Mineola)
FIG.2 (e) shows the measurement result of Mineola.
In Mineola, the temperature rose slightly after immersion in the antifreeze and then decreased to 0 ° C. And it became constant for about 10 minutes around 1 ° C. to 0 ° C., and then the temperature decreased relatively quickly.

(Orange)
FIG. 2 (f) shows the measurement results of mandarin oranges.
In mandarin orange, the temperature rose slightly after immersion in antifreeze and then decreased to 0 ° C.
And it became constant for about 10 minutes around 0 ° C to -1 ° C, and then the temperature dropped relatively quickly.

  "Grapefruit", "Red sweet summer", "Navel", "Orange", "Mineola", and "Tangerine". These are not damaged in the endothelium even after freezing and after thawing, soaking the juice from the inside of the endothelium It was not allowed to go out. For citrus fruits having an outer skin and endothelium as described above, when frozen by an air blast method, the endothelium may be damaged and fruit juice may ooze out (for example, described in JP2011-130700A). In the case of the frozen product, damage to the endothelium was suppressed.

(melon)
FIG. 3A shows the measurement result of melon.
In melon, it became constant at around 4 ° C for about 20 minutes after being immersed in antifreeze, and then the temperature decreased at a constant rate to -2 ° C. The temperature decreased relatively quickly from -2 ° C.

(Kiwi)
FIG.3 (b) shows the measurement result of kiwi.
In kiwi, after being immersed in the antifreeze solution, the temperature became constant at around 5 ° C., and then the temperature dropped to −2 ° C. And it became constant for about 5 minutes around -2 ° C, and then the temperature dropped relatively quickly.

(Grape)
FIG.3 (c) shows the measurement result of grape.
In grapes, the temperature dropped relatively quickly after being immersed in the antifreeze.

<Example B>
The relationship between the distance to the center of the fruit and the time required for freezing (freezing time) was evaluated.

Table 1 shows the weight (g), the thickness of the peel (mm), the distance to the center (mm), and the center of the fruit at −5 ° C. and −10 ° C. for each fruit used in Example A. It shows the time (minutes) required until the time and the moisture (%).
The thickness of the skin was measured by measuring the thickness of the skin at the top (1 point), the bottom (1 point), and the side (2 points) of these fruits, and averaging the results.
The distance to the center was determined by measuring the shortest part of the distance from the skin surface to the fruit center.
For the moisture content, the value described in the resource survey subcommittee report “Japan Food Standards Ingredients 2010” (Ministry of Education, Culture, Sports, Science and Technology, Science and Technology / Academic Technology Council) was used. The values for “Red sweet summer”, “Mineola”, and “Tangerine” are listed as “Natsumikan”, “Tan Zero”, and “Yunshu Mikan”, respectively.

  FIG. 4 is a graph showing the relationship between the distance to the center and the time required for the center temperature to reach −5 ° C. "Grapefruit", "Red sweet summer", "Navel", "Orange", "Mineola", "Tangerine", "Melon", "Kiwi", and "Grape" The following formula (1) is derived.

y = 1.6 x + z (y: freezing time (min), x: distance to center (mm), z: -7 ± 20) (1)
In the formula (1), “z” is preferably “−27 to 13”, more preferably “−17 to −3”, still more preferably “−12 to −2”, and still more preferably. “−7”.

Thus, by using the formula (1), by grasping the distance to the center of the fruit, the time for immersing the fruit in the antifreeze liquid in the temperature range of −25 ° C. to −35 ° C. is obtained. It will be.
It is considered that the time of immersing the fruit in the antifreeze solution to freeze the fruit is particularly affected by the distance to the center among the characteristics of the fruit. This is because most fruits have a moisture content of 80-90%, and in freezing fruits using antifreeze, the effect of the type of fruits (fruit components) is small compared to the distance to the center. It is estimated that.
Therefore, by satisfy | filling Formula (1), the loss of time by extension of time to immerse a fruit in an antifreeze liquid is suppressed, preventing incomplete freezing of a fruit.

The time for immersing each fruit in the antifreeze at −25 ° C. to −35 ° C. is preferably as follows. The “fruit diameter” is a numerical value measured with a major axis.
“Grapefruit” (fruit diameter of about 80 mm to 120 mm) is preferably 30 minutes or more, more preferably 35 minutes to 60 minutes, and further preferably 35 minutes to 45 minutes.
“Red sweet summer” (about 80 mm to 102 mm) is preferably 60 minutes or more, and more preferably 70 minutes to 80 minutes.
The “navel” (about 61 mm to 80 mm) is preferably 60 minutes or more, more preferably 60 minutes to 75 minutes, and further preferably 65 minutes to 70 minutes.
“Orange” (about 60 mm to 80 mm) is preferably 55 minutes or longer, more preferably 55 minutes to 65 minutes, and further preferably 60 minutes to 65 minutes.
“Mineola” (about 60 mm to 80 mm) is preferably 35 minutes or more, more preferably 35 minutes to 45 minutes, and further preferably 35 minutes to 40 minutes.
The “mandarin orange” (about 50 mm to 73 mm) is preferably 30 minutes or longer, more preferably 30 minutes to 40 minutes, and further preferably 35 minutes to 40 minutes. Further, the “mandarin orange” (diameter of about 73 mm to less than 88 mm) is preferably 30 minutes or more, more preferably 35 minutes or more, and further preferably 35 minutes to 45 minutes.
“Melon” (about 90 mm to 120 mm) is preferably 60 minutes or more, more preferably 65 minutes to 75 minutes, and further preferably 70 minutes to 75 minutes.
The “kiwi” (basic weight of fruit is about 115 g to 145 g) is preferably 20 minutes or more, more preferably 20 minutes to 30 minutes, and further preferably 25 minutes to 30 minutes.
About "grape" (basic weight of a bunch of about 200 g to 400 g), it is preferably 5 minutes or more, more preferably 5 minutes to 10 minutes.

  As shown in FIG. 4, when the distance to the center is the same, compared to the fruit vegetable “melon”, the citrus “red sweet summer”, the orange “navel” and “orange” There was a tendency to require freezing time, and compared with the grapefruit “grapefruit”, the mandarin orange “Tangerine” and the tanzero “Mineola” tended to require freezing time. Therefore, for the fruits that have the same distance to the center, select the ones that require more time, such as “Red Sweet Summer”, “Navel”, “Orange”, “Tangerine”, “Kiwi”, and “Grape When the approximate straight line is calculated using these measurement results, the following equation (2) is derived.

  y = 3.0 x + z (y: freezing time (min), x: distance to center (mm), z: -45) (2)

For this reason, by setting the freezing time so as to satisfy the formula (2) when the temperature of the antifreeze liquid is in the range of about −25 ° C. to −35 ° C., the freezing time is more reliably frozen (at least the center of the fruit). In the range of −5 ° C. or less), more fruits will be included.
By satisfying the formula (2), as compared with the case where the present configuration is not provided, it is possible to more reliably prevent the fruit from being completely frozen and to make the fruit soaked in the antifreeze liquid longer. Time loss due to conversion is suppressed.

On the other hand, as shown in FIG. 2, the citrus “red sweet summer”, orange “navel” and “orange” are compared to other fruits when the temperature is constant after immersion in antifreeze. Tend to be longer. This is presumed to be due to the particularly low thermal conductivity of the pericarp in citrus and oranges. Moreover, the grapefruit “grapefruit” continued to decrease at a constant rate without going through the process of constant temperature after being immersed in the antifreeze. This is presumed to be due to the particularly high thermal conductivity of the skin for grapefruits.
Therefore, citrus “red sweet summer”, orange “navel” and “orange”, grapefruit “grapefruit” excluding these “melon”, “mineola”, “mandarin”, “kiwi”, and “ “Grapes” The following equation (3) is derived by calculating an approximate straight line using these measurement results.

y = 1.7 x + z (y: freezing time (min), x: distance to center (mm), z: -18 ± 4) (3)
In the formula (3), “z” is preferably “−22 to −14”, more preferably “−20 to −16”, and further preferably “−18”.

  For this reason, by setting the freezing time so that the temperature of the antifreeze is −25 ° C. to −35 ° C. so as to satisfy the formula (3), fruits (at least “melons” of vegetable fruits, “Mineola” of tan zeros ”, The mandarin oranges“ citrus ”,“ kiwi ”and“ grape ”) will be frozen.

  FIG. 5 is a graph showing the relationship between the thickness of the pericarp and the time required for the center temperature to reach −5 ° C. “Red sweet summer”, “Navel”, “Orange”, “Mineola”, “Mikan” , And “melon”, an approximate straight line is calculated using these measurement results, the following equation (4) is derived. The grapefruit “grapefruit”, which is presumed to have a particularly high thermal conductivity of the fruit skin, and “kiwi” and “grape”, which are thinner than 1 mm compared to other fruits, were excluded.

y = 9.4 x + z (y: freezing time (min), x: skin thickness (mm), z: -2 ± 10) (4)
In the formula (4), “z” is preferably “−12 to 8”, more preferably “−7 to 3”, and further preferably “−2”.

Thus, by using the formula (4), by grasping the thickness of the pericarp, the antifreeze liquid in the temperature range of −25 ° C. to −35 ° C. is subjected to the fruits (at least “red sweet summer”, “navel”, The time for dipping “orange”, “mineola”, “mandarin orange”, and “melon”) will be known.
It is considered that the time of immersing the fruit in the antifreeze solution for freezing the fruit is particularly influenced by the distance to the center among the characteristics of the fruit, and further, the influence of the thickness of the pericarp is large among the distance to the center.

In the above embodiment, fruit having a substantially spherical appearance is used. However, the present invention is not limited to this, and it can also be applied to an elongated shape such as a banana or a substantially elliptical shape such as a mango.
You may make it apply not only to fruit but to vegetables. Examples of vegetables include edamame, turnip, pumpkin, cucumber, daikon, tomato, eggplant, carrot, garlic and the like.

  The distance to the center of the fruit may be substituted by the diameter of a substantially spherical fruit such as mandarin orange, orange or melon. Further, a long and thin shape such as a banana or a substantially elliptical shape such as a mango may be substituted by the diameter of the thickest portion.

In the above-described embodiment, the case where the distance to the center of the fruit and the thickness of the skin are used as the characteristics of the fruit and the freezing time is set according to the distance is described. Weight, fruit standards (for example, “National Standards for Fruits” set by the Ministry of Agriculture, Forestry and Fisheries, “Standard Shipping Standards” set by local governments, etc.) Or a combination of these may be used.
In addition to measuring the size and weight of each fruit individually and setting the freezing time for each, set the freezing time for each lot, packing box, classification at the time of shipment by the fruit handling company, etc. It may be.

For example, in the case of a mandarin orange, the refrigeration time may be set according to the size classification based on the fruit diameter (numerical value measured with the major axis). Specifically, 2S size (fruit diameter 50 mm or more and less than 55 mm), S size (55 mm or more and less than 61 mm), M size (61 mm or more and less than 67 mm), L size (67 mm or more) You may make it set freezing time according to each division, such as 73 size less than 73 mm), 2L size (73 mm or more and less than 80 mm), and 3L size (80 mm or more and less than 88 mm).
Or if it is a melon, you may make it set freezing time for every packing box according to the division (M, L, LA, 2L, etc.) at the time of shipment.

Claims (7)

Set the freezing time according to the characteristics of the fruit,
During this set freezing time, the fruit is immersed in antifreeze and frozen.
The manufacturing method of the frozen fruit which preserve | saves this frozen fruit in a freezer.   The method for producing frozen fruit according to claim 1, wherein the characteristic of the fruit is a distance to the center of the fruit. Pack the fruits before soaking in antifreeze,
The method for producing a frozen fruit according to claim 1 or 2, wherein the packaged fruit is immersed in an antifreeze and frozen.   The method for producing frozen fruit according to any one of claims 1 to 3, wherein the fruit belongs to the genus Citrus.   The manufacturing method of the frozen fruit of Claim 4 which sets freezing time according to each division | segmentation of the magnitude | size of the mandarin orange divided | segmented based on the diameter of a fruit.   The method for producing a frozen fruit according to claim 1, wherein the characteristic of the fruit is a thickness of a fruit peel.   The frozen fruit manufactured by the manufacturing method in any one of Claims 1 thru | or 6.

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