JP2013162748A - Method for processing water spinach, and water spinach frozen food - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for freeze processing in order to obtain water spinach (Ipomoea aquatica) retaining the green color of the water spinach and excellent in preservability.SOLUTION: A method for processing water spinach includes: a dividing process (step S4) of dividing the water spinach into its leaves and stems; a first heating process (step S5) of heating the divided stems for 60 s in salad oil, refined oil, corn oil, soybean oil, sesame oil, rapeseed oil, or safflower oil at 170-190°C; a second heating process (step S5) of heating the divided leaves for 30 s in salad oil, refined oil, corn oil, soybean oil, sesame oil, rapeseed oil, or safflower oil at 150-170°C; and a freezing process (step S7) of freezing the water spinach leaves and stems after the first and second heating processes. As a result of this, oxidizing enzyme of the water spinach is inactivated.

Description

  The present invention relates to a method for producing frozen vegetables, in particular, air-core vegetables (also referred to as common vegetables or yosai), and frozen foods of air-core vegetables.

  Frozen vegetables are one method for preserving vegetables for a long time. Frozen vegetables are generally subjected to a blanching treatment in which they are exposed to hot water or steam at 80 to 100 ° C. for a predetermined time to completely inactivate the oxidase, and then stored frozen. The blanching process is an effective method for root vegetables among frozen vegetables. However, chlorophyll contained in the green vegetable tissue is less susceptible to heat and acid than green vegetables among frozen vegetables, so the green color of the green vegetables fades due to blanching, the vividness is lost, and brown In many cases, the value was significantly reduced, such as discoloration.

  Patent Document 1 has been proposed as means for preventing such discoloration and fading of green vegetables. In the method described in Patent Document 1, a green vegetable is blanched and then immersed in an alkaline solution, and a film-forming substance such as potato starch is applied to the surface of the green vegetable. A film is formed on the surface of the green vegetable by heating the film-forming substance with hot water or the like.

JP 2008-193926 A

  However, the method disclosed in Patent Document 1 has problems such as an unfavorable taste due to an alkaline solution. In addition, one of the green vegetables, air-core vegetables (also called Tsuna and Yosai, scientific name Ipomoea aquatica), even when exposed to hot water or steam at 80-100 ° C for a predetermined time, green discoloration and fading occur. It was.

  Therefore, an object of the present invention is to provide a processing method for obtaining an air-core vegetable that maintains the green color of the air-core vegetable after the freezing treatment and has good storage stability.

  The first aspect of the method for processing air-core vegetables is a first step of dividing the air-core vegetables into their leaves and stems, and heating the classified stems in edible oil at 170 ° C. to 190 ° C. for 60 seconds. A heating step, a second heating step in which the separated leaves are heated in edible oil at 150 ° C. to 170 ° C. for 30 seconds, and after the first and second heating steps, the leaves and stems of the air-core vegetables are frozen. A refrigeration treatment step.

In the second aspect, the edible oil contains any of salad oil, white squeezed oil, corn oil, soybean oil, sesame oil, rapeseed oil, and safflower oil.
The third aspect of the method for processing air-core vegetables is the step of frying seasonings at 140 ° C. to 160 ° C., after the heating step and before the freezing treatment step, And a mixing step of mixing.
The frozen food of air core vegetables is manufactured by the processing method of air core vegetables of the 1st to 3rd viewpoint.

  According to the present invention, the air-core vegetables after the freezing treatment can maintain a green color.

It is a flowchart of the manufacturing method of frozen air-core vegetables. It is a flowchart of the manufacturing method of the freezing process of the seasoned air-core vegetable.

<First Embodiment>
The frozen empty core vegetable according to the first embodiment is a method for producing a frozen empty core vegetable without seasoning.
FIG. 1 is a flowchart of a method for producing frozen air-core vegetables.

  In step S01 of FIG. 1, the empty core vegetables delivered from a farmer or the like are received and the empty core vegetables are weighed. Delivered air-core vegetables remain cut and have no roots. In the cut air-core vegetables, the stem portion and the leaf portion are not separated.

In step S02, sorting is performed based on the diameter of the stalks of the empty core vegetables. Some air-core vegetables are damaged or have poor colors. Trimming is performed to remove such damaged air-core vegetables.
In step S03, the empty core vegetables are washed. Wash several times with clean water.
In step S04, the cleaned air-core rape leaves and stems are separated. For the next heating step, the cut leaves and stems are kept in separate sections.

  In step S05, heat treatment is performed on the empty core vegetables (separate leaves and stems). In the heat treatment, empty core vegetables are put into edible oil heated to a predetermined temperature. Vegetable oil can be used as the edible oil. Specific examples of the vegetable oil include soybean oil, sunflower oil, corn oil, sesame oil, rapeseed oil, safflower oil, peanut oil, coconut oil, and mixtures thereof. Details of the heat treatment will be described later.

In step S06, the air-conditioned vegetables heated to about 160 ° C. to 180 ° C. by the heat treatment are cooled and dried. The air-conditioned vegetables are dried in a room whose temperature is adjusted to 15 ° C.
In step S07, the empty core vegetables cooled to around 15 ° C are rapidly frozen to minus 18 ° C or lower.
In step S08, the frozen air-core vegetables are packed in a plastic bag or the like so as to have a predetermined weight.
In step S09, air is removed from the plastic bag, and the plastic bag is evacuated and sealed.

In step S10, a metal detector is used to check whether or not the air-packed vegetables are mixed with a metal detector. In step S11, 10-12 bags of plastic bags are packed in a freezer so that it can be easily stored and transported. And store in a freezer at -25 ° C or lower.

Second Embodiment
The frozen empty core vegetable according to the second embodiment is a method for producing a frozen empty core vegetable without seasoning.
FIG. 2 is a flowchart of a manufacturing method for the frozen processing of seasoned air-core vegetables.
Steps S01 to S05 in FIG. 2 are the same as the flowchart of the first embodiment described with reference to FIG.

In step S21, a plurality of seasonings are prepared. Prepare garlic, bean drum (touchi), oyster sauce, soy sauce and sesame oil as seasonings.
In step S22, the seasoning prepared in step S21 is mixed for about 1 minute at 140 ° C. to 160 ° C. and fried. The reason why the seasoning is fried at 140 ° C. to 160 ° C. is to make the temperature substantially the same as the temperature of the branched air-core vegetables in step S05.

In step S31, the empty core vegetables heated in step S5 and the seasoning fried in step S22 are mixed. While mixing the empty core vegetables and the seasoning at room temperature, the temperature of the empty core vegetables becomes 80 ° C. or lower.
In step S32, air-core vegetables that have become 80 ° C. or lower are packed into a plastic bag or the like so as to have a predetermined weight.
In step S33, air is removed from the plastic bag, and the plastic bag is evacuated and sealed.
In step S34, the empty core vegetables put in the plastic bag are cooled to room temperature.

In step S35, the air-core vegetables cooled to around 15 ° C are rapidly frozen to minus 18 ° C or lower.
In step S36, it is inspected with a metal detection device whether or not metal is mixed in the packaged air-core vegetables. This step is the same as step S10.
In step S37, the plastic bag is packed into 10 to 12 bags and stored in a freezer at -25 ° C or lower so that it can be easily stored and transported in the freezer. This step is the same as step S10.

<Heat treatment step S5>
In general, blanching means that frozen vegetables are heated to about 75 to 80% of cooking heat by being exposed to hot water or steam at 90 to 100 ° C. before being rapidly frozen. As with leafy vegetables such as spinach, even when blanched with hot water at about 100 ° C. or steam at about 120 ° C., the freshly preserved air-red vegetables had green discoloration or fading. The inventor diligently researched and found conditions for suppressing discoloration or fading of the frozen cored vegetables.

  As described in step S4 of the flowchart of FIG. 1 or FIG. 2, the stems and leaves of the air-core vegetables are separated.

Example 1
Heat the stalks of empty-core vegetables as follows. Heat 7 liters (6.3 kg) of cooking oil to 180 ° C. There, an empty core vegetable stem (800 g to 900 g) was added, and the empty core vegetable stem was heated for 60 seconds.

(Example 2)
Heat the empty core rape leaves as follows. Heat 7 liters (6.3 kg) of cooking oil to 160 ° C. There, empty core rape leaves (800 g to 900 g) were added and heated for 30 seconds.

  The amount of edible oil (g) and the amount of empty core vegetable (g) can be changed as appropriate, but it is preferable to heat with an amount of edible oil that is about 7 times or more the amount of empty core vegetable. This is to prevent the temperature of the edible oil from dropping suddenly when the empty core vegetables are added.

  The stems and leaves of these empty-core vegetables were examined to see if the oxidase was inactivated by the reagent. As a result, the oxidase contained in the stems and leaves of air-core vegetables was inactivated. Moreover, the green color of the air-core vegetables was kept.

  In addition, the test | inspection whether the oxidase was inactivated was performed in the following procedures. First, 10 g of stalks or leaves of air-core vegetables are ground finely. Then mix with 30 ml of pure water. 20 ml of distilled water is put into a test tube, and 2 ml of stalks or leaves of ground aired vegetables are put into the test tube. A reagent consisting of 1 ml peroxide hydrocarbon and 1 ml glycol is placed in a test tube. Wait 3 minutes and 30 seconds after adding the reagent. And if the color in a test tube changes to orange, it shows that the oxidase of air-core vegetables is still activated. If the color in the test tube did not change, it indicates that all the oxidase in the empty-core vegetable was inactivated.

(Comparative Example 1)
The stalks of air-core vegetables were heated as follows. Heat 7 liters (6.3 kg) of cooking oil to 150 ° C. There, an empty core vegetable stem (800 g to 900 g) was added, and the empty core vegetable stem was heated for 60 seconds.

(Comparative Example 2)
The empty rape leaves were heated as follows. 7 liters (6.3 kg) of cooking oil is heated to 140 ° C. There, empty core rape leaves (800 g to 900 g) were added and heated for 30 seconds.

  The stems and leaves of these empty-core vegetables were examined for whether or not the oxidase was inactivated with a reagent containing iodine. As a result, the oxidase contained in the stems and leaves of air-core vegetables was partially inactivated but not completely inactivated. For this reason, the green-core vegetables produced in Comparative Example 1 and Comparative Example 2 were discolored or discolored in green during storage.

(Comparative Example 3)
The stalks of air-core vegetables were heated as follows. Heat 7 liters (6.3 kg) of cooking oil to 200 ° C. There, an empty core vegetable stem (800 g to 900 g) was added, and the empty core vegetable stem was heated for 60 seconds.

(Comparative Example 4)
The empty rape leaves were heated as follows. Heat 7 liters (6.3 kg) of cooking oil to 180 ° C. There, empty core rape leaves (800 g to 900 g) were added and heated for 30 seconds.

  The air-core vegetables of Comparative Example 3 and Comparative Example 4 were dried due to the loss of moisture from the air-core vegetables, or burned and carbonized. For this reason, the empty core vegetables manufactured by the comparative example 3 and the comparative example 4 lost the commercial value.

  In 1st and 2nd embodiment, the example which stuffs empty core vegetables in a plastic bag was performed. However, air-core vegetables may be stored in an inverted trapezoidal tray partitioned by a partition wall, and about 50 g each may be placed in the tray and divided into quantities that can be used at a time in ordinary households.

Claims (4)

A sorting process for sorting the empty core vegetables into their leaves and stems;
A first heating step of heating the sectioned stems in edible oil at 170 ° C. to 190 ° C. for 60 seconds;
A second heating step of heating the sorted leaves in edible oil at 150 to 170 ° C. for 30 seconds;
After the first and second heating steps, a freezing treatment step for freezing the leaves and stems of the air-core rape,
A method of processing air-core vegetables comprising   The processing method of the air-core vegetable of Claim 1 in which the said edible oil contains any of salad oil, white squeezed oil, corn oil, soybean oil, sesame oil, rapeseed oil, and safflower oil. Stir-fried seasoning at 140-160 ° C;
The empty according to claim 1 or 2, further comprising a mixing step of mixing the heat-treated empty core vegetables and the fried seasoning after the heating step and before the freezing treatment step. Processing method of core vegetables. The frozen food of the air-core vegetable manufactured by the method as described in any one of Claims 1-3.