JP6994433B2 - Frozen food manufacturing method - Google Patents

Description

The present invention relates to a method for producing a frozen food.

Due to the development of freezing technology in recent years, various kinds of frozen foods are distributed and marketed. However, the conventional frozen food has a problem that the quality is deteriorated due to the damage caused by the freezing process. The conventional freezing method for frozen foods is mainly quick freezing by air blasting, but quick freezing using liquid nitrogen is also performed. Freezing with liquid nitrogen has a very high freezing rate, so damage to food can be suppressed.

Patent Document 1 includes processed eggplants or processed eggplants in which raw eggplants are fried at an oil temperature of 80 ° C. or higher and 100 ° C. or lower for 2 minutes or more and 10 minutes or less, then frozen, thawed, and then placed in a container and heat-treated. It is described that liquid nitrogen or air blast IQF method can be used for foods and the freezing treatment. In Patent Document 2, the eggplant is washed, cut, immediately immersed in washing water or salt water, drained and then fried, and then the fried eggplant is precooled and then quickly frozen by liquid nitrogen gas injection. It is described to produce frozen fried eggplant. Patent Document 3 describes that a frozen fried food is produced by ultra-rapid freezing the oiled fried food by a liquid nitrogen immersion method or the like.

Japanese Unexamined Patent Publication No. 2016-182043 Japanese Unexamined Patent Publication No. 2000-139393 Japanese Unexamined Patent Publication No. 2001-224318

Conventionally, frozen foods obtained by freezing oiled vegetables have drawbacks such as unsatisfactory texture after thawing, poor color tone, and unfavorable appearance even when frozen in liquid nitrogen. Had had. The present invention provides a high quality frozen food containing oiled vegetables having a good texture and appearance even after thawing.

The present inventors can improve the texture and appearance of frozen oiled vegetables after thawing by immersing the oiled vegetables in water or a seasoning liquid and then immersing them in liquid nitrogen. I found.

Therefore, the present invention provides a method for producing a frozen food product, which comprises immersing oiled vegetables in water or a seasoning liquid and then immersing them in liquid nitrogen.

According to the present invention, it is possible to suppress deterioration of texture and color tone due to freezing of oily vegetables. According to the present invention, it is possible to provide a high-quality frozen food containing frozen oil-butterfly vegetables having an excellent texture and appearance after thawing.

In the method for producing a frozen food of the present invention, oiled vegetables are soaked in water or a seasoning liquid before being soaked in liquid nitrogen.

The types of oiled vegetables include fruit vegetables such as eggplant, okra, peppers, pumpkin, and zucchini, flower vegetables such as broccoli, stem vegetables such as asparagus, bamboo shoots, onions, and onions, carrots, lotus roots, and burdock roots. , Root vegetables such as radish, potatoes, beans, mushrooms, etc., but are not particularly limited. Examples of preferred vegetable types include zucchini, lotus root, peppers, carrots, asparagus and eggplant. More preferably, the oiled vegetables are eggplants.

Vegetable oiling can be done by an appropriate procedure according to the type of vegetables. Preferably, the vegetables are cut to a suitable size before oiling. The size of vegetables can be appropriately set according to the type and recipe. Liquid nitrogen From the viewpoint of maintaining the texture and appearance of frozen vegetables, the mass of vegetables before oiling is preferably 25 g or less for each piece, more preferably 20 g or less for each piece, and 2 to 20 g for each piece. The degree is more preferable. The dimensions of vegetables before oiling are preferably 2 to 10 cm on the long side, 0.8 to 4 cm on the short side, and 0.5 to 4 cm in thickness, preferably 4 to 8 cm on the long side and 1 to 3.5 cm on the short side. A thickness of about 1 to 2 cm is more preferable. Then, these vegetables are sprinkled as they are or if desired, and then put into hot oil and fried in oil. The temperature and time of the oil butterfly can be appropriately set according to the type of vegetables and the recipe.

If necessary, the oiled vegetables are lightly drained and then soaked in water or a seasoning liquid. Prior to the soaking, the oiled vegetables may be allowed to cool once. The temperature of the water or seasoning liquid used for dipping is not particularly limited, but is preferably 5 to 15 ° C. The amount of water or seasoning liquid used for soaking may be such that the oiled vegetables can be sufficiently soaked so that the whole of the oiled vegetables is soaked in water or seasoning liquid.

Examples of the water or seasoning liquid include water, soup stock, seasonings (for example, salt, sugar, honey, mirin, sake, soy sauce, miso, vinegar, oil, powdered soup stock, umami seasoning, etc., and mixed seasonings thereof. ), Liquid seasonings (noodle soy sauce, liquid sauce, etc.), mixed solutions thereof, etc., but are not particularly limited. The water or seasoning liquid may contain an additive such as a shelf life improver (for example, sodium acetate). Preferably, the water or seasoning liquid contains sugar or salt, and more preferably contains sugar and salt. The concentration of sugar and salt in the water or seasoning liquid is not particularly limited, but the concentration of sugar is preferably 2 to 25% by mass, more preferably 4 to 22% by mass, and further preferably 5 to 15% by mass. The salt concentration is preferably 1.0 to 8.0% by mass, more preferably 2.0 to 6.0% by mass, and further preferably 2.5 to 5.0% by mass.

The time for immersing the oiled vegetables in the water or seasoning liquid can be changed according to the size of the vegetables and the like, but is preferably 5 minutes or more, more preferably 30 minutes to 24 hours. , More preferably 1 to 24 hours. Preferably, the mass of the oiled vegetables after the liquid nitrogen immersion treatment, which will be described later, is increased by 101% with respect to the mass of the oiled vegetables before being immersed in the water or the seasoning liquid. As described above, the immersion time in the water or the seasoning liquid is adjusted so as to be more preferably about 101 to 113%, still more preferably about 101 to 110%.

Then, in the method of the present invention, oiled vegetables soaked in the water or seasoning liquid are soaked in liquid nitrogen. Before the liquid nitrogen soaking, it is preferable to lightly remove the water on the surface of the oiled vegetables soaked in the water or the seasoning liquid by draining the vegetables. Preferably, in the liquid nitrogen immersion, the oiled vegetables may be placed in a tank filled with liquid nitrogen and the vegetables may be immersed in liquid nitrogen. Preferably, the package containing the oiled vegetables is placed in a tank filled with liquid nitrogen so that the oiled vegetables are immersed in liquid nitrogen. The package may have a structure capable of immersing the vegetables inside in liquid nitrogen. Examples of the package include, but are not limited to, a container without a lid, a bamboo basket, and the like.

The time of immersion in liquid nitrogen can be appropriately adjusted according to the amount and size of the oiled vegetables or the size of the package, but is preferably 10 to 90 seconds, more preferably 15 to 60 seconds. , More preferably 20-40 seconds. If the liquid nitrogen immersion time is too short or too long, the foodstuff may be damaged. Further, if the liquid nitrogen immersion time is too long, the appearance of the frozen food may be deteriorated due to the damage of the food material and the mixing of debris generated by the damage.

Preferably, in the method of the present invention, the oiled vegetables after being soaked in liquid nitrogen are allowed to stand for about 10 to 60 minutes under the conditions of −10 to −50 ° C. and further frozen. Further, at that time, it is desirable to place the vegetables under a wind speed of about 3 to 12 m / s.

The oil-boiled vegetables that have been subjected to the quick freezing treatment by soaking in liquid nitrogen may be stored under normal freezing storage conditions (for example, −18 ° C. or lower). The frozen food provided in the present invention contains frozen oil butterflies and vegetables obtained by the above procedure. The frozen food provided in the present invention may contain only the frozen oil butterflies and vegetables, but may also contain other foodstuffs. The types of the other ingredients are not particularly limited. Further, the other foodstuff may be frozen in liquid nitrogen or frozen or frozen by other means.

The method for thawing the frozen food produced in the present invention is not particularly limited, and examples thereof include slow thawing such as normal temperature thawing, low temperature thawing, running water thawing, and rapid thawing such as microwave heating thawing. The frozen food produced by the method of the present invention can have a good texture and appearance even after thawing because discoloration and deterioration of texture due to freezing and freezing treatment of oily vegetables are suppressed.

Examples are given to illustrate the invention in detail, but the invention is not limited to the following examples.

Test Example 1
1) Preparation of soup stock 350 g of soup stock, 100 g of thick soy sauce, and 50 g of sugar were mixed in a pan and heated to prepare a seasoning liquid. Tap water was used as the water.

2) Cooking vegetables (fried eggplant)
Eggplant was cut into small pieces (10 to 15 g / piece), fried in oil at 180 ° C. for 1 minute and 15 seconds, and allowed to cool for 1 minute.
(Stir-fried eggplant)
Eggplant was cut into small pieces (10 to 15 g / piece), 20 g of oil was put in a frying pan, heated, stir-fried for 10 minutes, and allowed to cool for 1 minute.

3) The cooked eggplant obtained in 2) was immersed in the soaking water or the seasoning liquid (10 ° C.) prepared in 1) for 1 hour or 20 hours. The ratio of cooked eggplant: water or seasoning liquid was 2: 1 by mass ratio. During the soaking, the whole eggplant was soaked in water or seasoning liquid. After soaking, the eggplant was put into a colander and drained for 1 minute.

4) Salinity measurement The salinity concentration of the cooked eggplant obtained in 3) was measured (n ≧ 3). For the measurement, add 3 times the amount of ion-exchanged water to 1 eggplant (10.4 to 17.9 g), mix with a mill mixer for 10 seconds, and measure the salt concentration of the mixture with the food salinity meter TS-99 (Toko Kagaku). Measured at the laboratory). From the measured values, the salt concentration of the cooked eggplant was calculated.

5) Freezing treatment (quick freezing by immersion in liquid nitrogen)
The eggplant obtained in 3) was placed in a plastic container without a lid. The plastic container was submerged in a tank containing liquid nitrogen (Dewar bottle; Thermocut D-3001 Thermos Co., Ltd.), and the eggplant was immersed in liquid nitrogen for 30 seconds. Then, the eggplant was allowed to stand for 30 minutes or more in an environment of −35 ° C. and a wind speed of 8 m / s.
(Rapid freezing by air blast)
The eggplant obtained in 3) was allowed to stand for 30 minutes or more in an environment of −35 ° C. and a wind speed of 8 m / s, and then frozen.

6) Weight measurement The weight of the cooked eggplant obtained in 2) and the weight of the frozen eggplant obtained in 5) were measured (n ≧ 5). The water content of the fried eggplant was reduced by about 10 to 13% as compared with the fresh eggplant. The water content of the stir-fried eggplant was reduced by about 12 to 16% as compared with the fresh eggplant. The ratio (%) of the weight of the eggplant after freezing to the weight of the cooked eggplant was calculated as the liquid content increase.

7) Evaluation The eggplant frozen in 5) was placed in a pouch bag, sealed, and stored in a freezer at an internal temperature of −20 ° C. for 6 months. A part was taken out every month and allowed to stand in a refrigerator (5 ° C.) for 6 hours or more to thaw. The texture and appearance of the flesh of the eggplant after thawing were evaluated by a panel of 10 people according to the following evaluation criteria, and the average score was obtained. The evaluation results are shown in Table 1.
〔Evaluation criteria〕
(Texture)
5 points: Texture that can be eaten deliciously without deterioration such as softening 4 points: Texture that can be eaten quite deliciously although it feels slightly deteriorated 3 points: Food that feels deterioration but has no problem as a product Texture 2 points: Texture that is considerably deteriorated and is a hindrance to the product 1 point: Texture that is significantly deteriorated and resistant to eating (appearance)
5 points: There is no color bleeding or fading, and there is no problem with the appearance. Appetite-inducing appearance.
4 points: There is some color bleeding and fading, but there is no problem with the appearance. Appetite-inducing appearance.
3 points: There are color bleeding and fading, but it looks good as a product. Appetite does not lose its appearance.
2 points: Appetite is slightly lost due to noticeable color bleeding and fading.
1 point: Appetite is lost due to severe color bleeding and fading.

Test Example 2
1) Cooking of fried vegetables Asparagus was cut into 4 to 5 cm tubes (3.6 to 6.2 g each piece), fried in oil at 180 ° C for 1 minute and 15 seconds, and allowed to cool for 1 minute.
The peppers were cut into tubes of 1 to 1.5 cm (each piece 2.0 to 3.5 g), fried in oil at 180 ° C. for 1 minute, and allowed to cool for 1 minute.
Cut carrots into half-moons (3.3 to 4.5 g each piece, 3 to 4 cm long side, 1.5 to 2 cm short side, 1 to 1.5 cm thick) and fry in oil at 180 ° C for 1 minute and 30 seconds. Allowed to cool for 1 minute.
Cut the lotus root into half-moons (10.0 to 17.0 g for each piece, 5 to 6 cm on the long side, 3 to 3.5 cm on the short side, 1 to 1.5 cm in thickness), and fry in oil at 180 ° C for 1 minute and 30 seconds. Allowed to cool for 1 minute.

2) Soaking and freezing treatment The fried vegetables from 1) were soaked in the seasoning liquid for 3 hours in the same procedure as in Test Example 1, then put into a colander and drained for 1 minute. As the seasoning liquid, the one having the same composition as that of Test Example 1 was used. The salt concentration of some of the soaked vegetables was measured by the same procedure as in Test Example 1 (n ≧ 3), and the rest were rapidly frozen by liquid nitrogen immersion or air blasting by the same procedure as in Test Example 1. The time of immersion in liquid nitrogen was 15 to 30 seconds.

3) Evaluation The same procedure as in Test Example 1 was used to evaluate the increased liquid content of the frozen vegetables and the texture and appearance of the vegetables after the frozen storage. However, for carrots and lotus roots, only texture evaluation was performed. The evaluation results are shown in Tables 2 and 3.

Claims (7)

A method for producing a frozen food product, which comprises immersing oiled vegetables in water or a seasoning liquid for 30 minutes to 24 hours and then immersing them in liquid nitrogen. The method according to claim 1, wherein the water or seasoning liquid contains sugar or salt. The method according to claim 1 or 2, wherein the immersion time in liquid nitrogen is 10 to 90 seconds. 13 . the method of. The method according to claim 4 , wherein the mass of the oiled vegetables after soaking in liquid nitrogen is 101% or more of the mass of the oiled vegetables before being immersed in the water or the seasoning liquid. The method according to any one of claims 1 to 5 , wherein the weight of the vegetables before oiling is 25 g or less. The method according to any one of claims 1 to 6 , wherein the vegetables are lotus root, peppers, carrots, asparagus, or eggplant.