JP2518674B2 - Method for producing sugar-impregnated fruit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to strawberry, kiwi, apple, pineapple,
The present invention relates to a method for producing a sugar solution-impregnated fruit, which is obtained by impregnating fruit such as oranges and grapes with a sugar solution.

[Conventional technology]

It is known that if fruits such as natural strawberries and kiwi are frozen as they are, they will have a hard texture like ice. Therefore,
A technique is known in which a part of the water in the fruit is replaced with sugar solution, oil, alcohol or the like to maintain a soft texture when frozen.
In this case, it is said that it is desirable to replace the water content in the fruit with the sugar solution in order to utilize the original flavor of the fruit.

A method for replacing the water in the fruit with a sugar solution is described in JP-A-61-268128. In the method disclosed herein, the raw material fruit is immersed in a sugar solution and microwave-heated, and then the immersion state in the sugar solution is maintained to replace a part of water in the fruit with the sugar solution.

However, the above method has the following problems. That is, (1) microwave heating is carried out while the fruit is immersed in the sugar solution, and therefore it is necessary to heat the fruit and the sugar solution. Components, especially dyes, elute in the sugar solution.

(2) Since the immersion in the sugar solution after heating the fruit is performed under normal pressure, the impregnation of the sugar cannot be completed in a short time, and the pigment in the fruit is eluted during the immersion treatment.

Therefore, the sugar solution-impregnated fruit obtained by the method described in JP-A No. 61-268128 is completely unsatisfactory in color tone.

[Problems to be Solved by the Invention]

Therefore, the present invention does not lose the original color or fade as in the prior art at the time of producing a sugar solution-impregnated fruit,
It is an object of the present invention to provide a production method capable of obtaining a sugar solution-impregnated fruit having a sufficiently satisfactory color tone. Also,
Another object of the present invention is to provide a method for producing a sugar solution-impregnated fruit, which allows a sugar solution-impregnated fruit having a soft texture even when the sugar solution-impregnated fruit is frozen.

[Means for solving the problem]

The present invention was made based on the finding that the above-mentioned problems can be efficiently achieved by first subjecting a fruit to microwave irradiation treatment and then immersing the fruit in a sugar solution under specific conditions.

That is, the present invention provides a method for producing a sugar solution-impregnated fruit, which comprises immersing a raw material fruit in a sugar solution under reduced pressure after microwave irradiation treatment.

Examples of fruits used as a raw material in the present invention include strawberries, kiwi, apples, pineapples, mandarins, grapes, peaches, and the like, but fruits other than these can also be targeted. Among these, the present invention is most suitable for the treatment of strawberries, kiwi, etc., in which the dye is significantly eluted in the conventional sugar impregnation treatment.

In the present invention, the above-mentioned raw material fruit is used after washing with water and peeling if necessary, but the fruit can be further molded and used. Here, in the case of molding, the raw fruit is cut into small pieces, or the raw fruit is molded into a desired shape as it is. When cutting fruits, it is desirable that the sizes of the cut shapes are the same. by this,
The microwave irradiation treatment makes it easy to uniformly heat the fruit and effectively impregnate sugar.

In the present invention, the above-mentioned raw fruit can be used as it is, but for the purpose of preventing the discoloration of the fruit, the raw fruit can be immersed in a saline solution and then subjected to microwave irradiation treatment. The concentration of the saline solution is, for example, 0.5 to 2%, and L-ascorbic acid, citric acid or the like can be added to the saline solution.

The present invention is characterized in that the raw material fruit is subjected to microwave irradiation treatment in air or in an inert gas such as argon gas. That is, the fruit is uniformly heated by the microwave irradiation treatment to soften the fruit tissue. Here, it is desirable to perform the microwave irradiation process under the conditions that satisfy the following conditions.

(A) The raw fruit is directly irradiated with microwaves to bring the raw fruit to a temperature of 40 to 80 ° C, preferably 50 to 70 ° C.

In other words, if the temperature of the heated fruit does not reach 40 ℃,
This is because the fruit tissue cannot be softened sufficiently and the texture of the fruit becomes hard when frozen. On the other hand, the temperature rise of the fruit is 80 ℃
When boiling over the temperature, the fruit tissue tends to collapse. Thus, the above temperature range can sufficiently soften the fruit tissue and achieve a soft texture upon freezing.

(B) The microwave irradiation is stopped before water is exuded from the raw fruit.

In other words, if the microwave irradiation treatment is continued for a certain period of time (or if the fruit boils during the microwave treatment), water will seep out from the fruit, but microwave irradiation will be stopped before this happens. Is good.

When water exudes from the fruit during heating in this way, the components in the fruit, especially the pigment, elutes together with the water.

Therefore, by stopping the microwave irradiation before exuding the water, the fruit tissue can be softened without the loss of the pigment.

As a specific condition of the microwave irradiation process satisfying the above conditions (A) and (B), for example, a microwave having a normal frequency of 915 MHz or 2450 MHz is used and the process is performed at about 200 W.

When microwave irradiation processing is performed under such conditions (a)
Due to the principle of high frequency induction heating, the inside and surface of the fruit are evenly heated, and the fruit tissue is softened uniformly. (B) The surface drying of the fruit does not occur with microwave heating, and the fruit tissue is softened uniformly. Since (C) there is no heat medium such as a solution in the surroundings, there is no elution of the fruit component, and (d) there are excellent effects such as the time required for softening the fruit tissue is short.

In the present invention, the microwave-irradiated fruit is then immersed in a sugar solution under reduced pressure. Here, as sugar for preparing a sugar solution, sugars such as granulated sugar, brown sugar, rock sugar, glucose, maltose, starch syrup, natural sweetener, artificial sweetener and the like can be mentioned. In the present invention, the sugar solution has a concentration of 30% by weight (hereinafter abbreviated as%) or more, preferably 50%.
It is preferable to use one having a weight% or more. Here, the mixing ratio of the fruit to be dipped and the sugar solution may be arbitrary, and the fruit is preferably soaked in the sugar solution.

In the present invention, the temperature of the fruit when immersed in the sugar solution is arbitrary, but after the microwave irradiation treatment, the temperature of the fruit is 40 to 80 ° C.
It is preferable to immerse in a sugar solution kept at room temperature to 80 ° C., preferably room temperature to 70 ° C. under reduced pressure while the temperature is on, to keep the immersed state and return to normal pressure.

Here, the dipping method is a conventional method, for example, it is preferable that the raw fruit is contained in a retainer formed of a mesh-shaped material, and the depressurizing process is performed while the retainer is immersed in the sugar solution in the depressurizing device. More specifically, the concentration of the sugar solution is 30 to 70.
%, It is immersed under reduced pressure of 1000 to 14000 pascals (Pa), preferably 1000 to 4000 pascals for 1 to 20 minutes, preferably 3 to 5 minutes. When the pressure is higher than 14000 Pascal, the treatment time becomes long, the pigment in the fruit is eluted into the sugar solution, and the fruit tends to be too sweet. On the other hand, when the pressure is lower than 1000 Pascal, running costs are high, workability is poor, and fruits and sugar solutions are likely to boil. In the above range, the pulp can be sufficiently replaced with the sugar solution in a short time, and a fruit having a soft texture when frozen can be obtained. Further, the original color of the fruit is not lost, and an appropriate sweetness can be obtained.

The above-mentioned dipping treatment can be carried out by dipping the fruit in a sugar solution under reduced pressure and then returning to normal pressure by repeating 1 to 3 times.
By the immersion treatment, the sugar concentration in the fruit after the treatment was 10-30
It is desirable to do so as to be%. As a result, a soft texture upon freezing is achieved, and the sweetness of the fruits is also good.

After the immersion treatment, the fruit and sugar solution are separated by a conventional method to obtain the desired sugar solution-impregnated fruit.

The sugar solution-impregnated fruit thus obtained is suitably used as a frozen food or a material for a frozen food. That is, the sugar solution-impregnated fruit obtained in the present invention is used as a material for ice cream, ice cake and the like, and has a soft texture even when frozen, and has the original color tone of the fruit. When the fruit is frozen, it is desirable to freeze the fruit immediately after the dipping treatment in order to maintain the good color tone of the fruit.

Therefore, the sugar solution-impregnated fruit produced by the present invention may be eaten as it is, or may be dried by a conventional method to give a dried food.

〔The invention's effect〕

According to the production method of the present invention, it is possible to easily produce a sugar solution-impregnated fruit that does not lose its original color, does not fade, is sufficiently satisfactory in color tone, and has a soft texture even when frozen. can do.

Next, the present invention will be described with reference to examples, but the present invention is not limited thereto.

Example 1 150 g of strawberries washed with water and cut in two in the vertical direction were placed on a shelf and stored in a microwave oven. Next, microwave irradiation treatment was performed at 200 W for 2.5 minutes using a 2450 MHz microwave. Water did not exude from the strawberries during the microwave irradiation treatment, and the temperature of the strawberries was 58 ° C.

After the microwave irradiation treatment was completed, the strawberries were placed in a retainer made of a mesh-like material, and the retainer was immersed in 400 ml of sugar solution (temperature: 25 ° C.) in a decompression device for decompression treatment. Here, as the sugar solution, a 50% -concentration sugar aqueous solution was used, and after dipping treatment under a reduced pressure of 2500 Pascal for 5 minutes, the pressure was returned to normal pressure.

The retainer was pulled up from the sugar solution in the decompression device to obtain the desired processed strawberry. The sugar concentration of this sugar solution-impregnated strawberry is 13%.
Then, the obtained sugar solution-impregnated strawberry retained the original red color tone of strawberry.

Also, when the strawberry impregnated with the sugar solution was placed on a cake and frozen, and the strawberry was eaten, the strawberry had a soft texture and retained the original red color tone of the strawberry.

Example 2 Kiwifruit was washed with water, peeled, and slice-cut (100 to 130 g) was placed on a shelf and placed in a microwave oven. Then use 2450MHz microwave, 2 at 200W
Microwave irradiation treatment was performed for a minute. Water did not exude from the kiwifruit during the microwave irradiation treatment, and the temperature of the kiwifruit was 60 ° C.

After the microwave irradiation treatment, the kiwifruit was stored in a retainer made of a mesh-like material, and the retainer was impregnated with 500 ml of sugar solution (temperature 25 ° C) in the depressurizer to perform depressurization treatment. . As the sugar solution, a 40% strength aqueous sugar solution was used, which was soaked under a reduced pressure of 7,000 Pascal for 7 minutes and then returned to normal pressure.

The retainer was pulled up from the sugar solution in the decompression device to obtain the target sugar solution-impregnated kiwifruit. The sugar concentration of the sugar solution-impregnated kiwifruit was 19%, and the obtained sugar solution-impregnated kiwifruit retained its original color tone.

Further, when the sugar solution-impregnated kiwifruit was frozen and consumed, the kiwifruit had a soft texture and the original color tone.

Comparative Example 1 150 g of strawberries washed in water and cut in two in the vertical direction were placed in a container, and immersed in 700 ml of sugar solution (temperature 60 ° C.) in the container for 60 minutes under normal pressure. Thus, a sugar solution-impregnated strawberry was obtained. The sugar concentration of this sugar solution-impregnated strawberry was 15%.

Comparative Example 2 Strawberries washed in water and cut into two pieces in the vertical direction 150g
And 400 ml of sugar solution having a concentration of 50% were placed in a container, and the container was placed in a microwave oven while strawberry was immersed in the sugar solution. The microwave irradiation treatment was performed at 200 W for 9 minutes using a 2450 MHz microwave. About 5 during microwave irradiation
The sugar solution boiled in minutes, and the temperature of strawberries was 95 to 100 ° C.

After the completion of the microwave irradiation treatment, the immersion state in the sugar solution was kept for 2 minutes in the container to obtain a sugar solution-impregnated strawberry. The sugar solution-impregnated strawberry had a sugar concentration of 15%.

The color tone of the sugar solution-impregnated strawberry obtained in Example 1 and the sugar solution-impregnated strawberries obtained in Comparative Examples 1 and 2 were measured by a hunter (manufactured by Nippon Denshoku Industries Co., Ltd., spectroscopic color difference meter SZ-Σ80). . The results are shown in Table 1.

As described above, Example 1 of the present invention and Comparative Examples 1 and 2
, There is a large difference in color difference = NBS unit (ΔE), and the sugar solution-impregnated strawberry obtained according to the present invention has the original redness, whereas the sugar solutions obtained in Comparative Examples 1 and 2 It can be seen that the impregnated strawberries have lost redness.

Claims (1)

(57) [Claims] 1. A method for producing a sugar solution-impregnated fruit, which comprises immersing a raw fruit fruit in a sugar solution under reduced pressure after microwave irradiation treatment.