JP4245458B2 - Frozen carrot - Google Patents

Description

  The present invention relates to a method for producing frozen carrots, which is a material for cooked foods with less texture and water separation, such as sponging of tissues by freezing, thawing and cooking, and a frozen carrot produced thereby, and the frozen It relates to cooked foods containing carrots.

  In recent years, the demand for frozen vegetables that can be easily cooked has been increasing with increasing consumer health and simplifying eating habits.

  However, when frozen vegetables are cooked and served on the table, it is difficult to reproduce the natural texture of vegetables that are felt when cooked from raw vegetables. At present, softening and water separation are remarkable, and the quality difference between raw and frozen products is large.

  Generally, in frozen and thawed vegetables, the tissue is destroyed by ice crystals formed during freezing, and the coarsening of ice crystals that occurs during freezing can cause water to separate from the tissue during thawing, resulting in significant quality. It decreases and the texture becomes worse.

  Usually, when producing frozen vegetables, a blanching treatment by heating is performed to prevent discoloration by an enzyme such as polyphenol oxidase, to prevent the occurrence of off-flavors, and to prevent contamination by microorganisms. However, it is known that the texture of many frozen vegetables becomes worse after freezing and thawing due to heat treatment such as blanching treatment. The reason for this is considered to be that the damage received by the cell wall is as large as heating, freezing, and thawing, and the flexibility of the cell wall is lost and the tissue becomes spongy during cryopreservation.

  By the way, as for root vegetables such as carrots, the texture of the carrots plays a very important role in the taste in addition to the taste, especially in carrots that are raw or lightly heated. As a conventional method for producing frozen carrots, a method in which carrots are peeled off, cut and then subjected to a heat-branching treatment at 95 to 100 ° C. for 2 to 5 minutes, followed by rapid freezing. However, the frozen carrot treated by such a method is inevitably streaked after thawing, and the use range of the frozen carrot has been limited.

  In general, various methods for reducing the ice crystals formed during freezing and for strengthening the tissue before freezing have been proposed in general for improving the texture of frozen vegetables.

  The former is a method in which an antifreeze substance is immersed in a tissue before freezing to make the water in the tissue antifreeze, that is, a method in which a sugar solution is infiltrated and frozen (Patent Document 1: Japanese Patent Laid-Open No. Hei 5-). No. 103587), a method of infiltrating and freezing a mixed solution of sugar and inorganic salts, sugar and ethanol, etc. (Patent Document 2: Japanese Patent Application Laid-Open No. H4-27375), and a mixed solution of urea or urea and sugar alcohol Is a method of permeating and freezing (Patent Document 3: JP-A-2001-224304).

  Further, as a method for strengthening the latter structure, a method of preheating in hot water at a relatively low temperature is known. This is because pectinesterase in the living body is activated during preheating, acts on the pectin, which is a component of cell walls and intercellular substances, and promotes demethylation of carboxyl groups. It is believed that the tissue hardens because the valent cations bind to form crosslinks and insolubilize the pectin. It is also known that the addition of a divalent cation, particularly a calcium salt, strengthens the cell wall by binding to pectin. Up to now, a method of heating at 60 ° C to 70 ° C for a maximum of 2 hours to harden the tissue (Non-patent Document 1: ARG.F00D CHEM., 20, 2.266.1972), at 60 ° C for 30 minutes A method of activating pectinesterase and planting with 10 mM calcium chloride aqueous solution (Non-patent Document 2: Report of Hokkaido Industrial Laboratory, 285, 189, 1986) has been reported.

  Patent application includes a method for preventing softening of vegetables and fruits characterized by preheating at least a surface product temperature of 45 ° C. to 75 ° C. for 10 to 180 minutes with water, dilute acidic water, or sugar solution (Patent Documents) 4: JP-A-54-107542), after immersing vegetables in a calcium aqueous solution at a low temperature, the temperature of the aqueous solution is raised to a range of 40 to 70 ° C. and kept for a certain period of time. Of vegetable softening (patent document 5: JP-A-60-237957) characterized by the above, medium temperature heat treatment in which the vegetables are kept at a temperature range of 49-70 ° C. for 5 minutes or more to produce sugar beet and pickles A method for producing sugar beet and pickles characterized by being incorporated into the method (Patent Document 6: Japanese Patent Laid-Open No. 5-68505), vegetables that are round or large cut are subjected to a tissue strengthening treatment Thereafter, a frozen vegetable manufacturing method characterized by subjecting to freezing treatment (Patent Document 7: Special (Kaihei 8-140570).

  In addition, the carrots used for frozen carrots have been examined for the difference in freezing suitability depending on the variety, but the growth period and maturity have not been examined so far and are used as fresh products. The same thing is used. For example, autumn and winter carrots are usually harvested 100 to 130 days after sowing, and those around this time correspond to M (~ L) size with high market needs, and the proportion of carrots with good quality is also high. . (The standard for carrot producers in Chiba Prefecture, the main production area, is S size 80-120g, M size 120-199g, L size 200-299g.)

Japanese Patent Laid-Open No. 5-103587 Japanese Laid-Open Patent Publication No. 4-27275 JP 2001-224304 A JP 54-107542 A JP-A-60-237957 JP-A-5-68505 JP-A-8-140570 ARG.F00D CHEM, 1972, Vol. 20, No. 2, 266 Hokkaido Industrial Research Institute Report, 1986, 285, 189

    Carrots are applied to the conventional methods for producing frozen vegetables by (a) reducing ice crystals formed during freezing by dipping in various solutions before freezing, or (b) strengthening the tissue before freezing. However, even if frozen carrots are manufactured, the carrots after thawing remain streaky, the texture is not excellent, and the quality difference in terms of texture with raw carrots is still large. It could not be manufactured.

  Furthermore, in carrots, from the viewpoint of hygiene, heat treatment such as blanching before freezing is inevitable, but frozen carrots that do not impair the texture even after heat treatment before freezing have been demanded. .

  Therefore, it is a frozen carrot that has little texture and water separation such as sponge formation by heating, freezing, and thawing (and cooking) before freezing, and has the same texture as raw carrots even after thawing. It is an object to provide a method for producing frozen carrots without any problems.

  “Straightness” refers to the expression of the physical texture of food when the food has a strong presence of fibers and muscles when it is chewed in the mouth. It is an index.

  “Sponge” or “sponge-like” expresses the physical properties of the food when the juice comes out when the food is put in the mouth and chewed. It is a representative example of food.

  The inventors of the present invention have intensively studied to obtain a carrot having an excellent texture even after heating before freezing, freezing, and thawing (and cooking), and have completed the present invention.

First, the present inventors examined carrot freezing pretreatment.
In general, frozen carrots are manufactured by a process of washing → peeling → cutting → heating treatment → cooling → freezing. However, if the heat treatment is performed before freezing, phenomena such as tissue spongy and streaks are observed, and the quality deteriorates. Conversely, when heat treatment is not performed, there is a possibility of discoloration and microbial contamination, and it is difficult to produce safe and stable carrots.

In order to solve these problems, the following method for producing frozen carrots has been devised.
After washing the carrot, before the cutting step, heat it for a short time so that heat is not transferred to the inside of the carrot, and then cool it quickly. After cooling, the epidermis including the heated part is removed, cut into an appropriate size, and then subjected to quick freezing.

  Note that the heat treatment is performed to reduce microorganisms adhering to the carrot skin surface. In terms of reducing microorganisms, a longer heating time is preferable, but if it is longer, heat is transferred to the inside of the carrot. Therefore, it becomes a state close to normal blanching, and the texture after freezing and thawing is reduced. In addition, when the heating temperature is low, heating for a long time is required to reduce microorganisms, and an enzyme related to browning is activated to cause browning.

  The method for producing frozen carrots according to the present invention has an exceptional effect that it is possible to provide frozen carrots that have almost no drip spillage or streak and are excellent in texture even after thawing. As a result, frozen carrots can be applied not only to the conventional limited cooking method but also to cooking of salads and the like according to raw food, and the range of use of frozen carrots can be expanded, so that carrots can be effectively used. .

  In the present invention, after washing the carrot, before the cutting step, it is heated for a short time so that heat is not transferred to the inside of the carrot, then cooled quickly, and after cooling, the epidermis including the heated part is removed, A carrot freezing method is provided which includes a step of cutting to a proper size and then performing quick freezing.

  Various well-known means, for example, heated water, a heated aqueous solution, and heated steam can be used for heating before freezing. Preferably, the quality of hygiene and texture can be maintained by performing in hot water at 90 to 100 ° C. for 30 seconds to 2 minutes, more preferably 45 seconds to 1 minute 15 seconds.

The cooling is preferably performed with water or an aqueous solution at 10 ° C. or lower, more preferably at 4 ° C. or lower.
Peeling is only required to remove the part where the texture is damaged by heating and to remove the skin layer where the majority of carrot browning substances are unevenly distributed, for example, about 0.5 to 4 mm, usually 1 to 2 mm. By removing it, the quality after thawing can be significantly improved. If the peel is thin, the possibility of browning in the portion close to the skin layer increases, and if the peel is thick, the yield decreases.

  Further, preferably, a dipping treatment in a sodium hypochlorite solution is performed before peeling and / or after cutting in order to prevent secondary contamination by microorganisms during the peeling and cutting steps.

  With these new treatment steps, there is no risk of microbial contamination, and the heated part is removed in the peeling process, so that it has become possible to produce frozen carrots that are extremely drip and spongy.

The inventors further examined the maturity of the carrot to be frozen.
Regarding the raw carrots used for frozen carrots, the difference in freezing suitability by varieties has been studied, but the growth period and maturity have not been studied deeply. There are two main types of carrot crops: those that are sown in the summer and harvested from autumn to winter, and those that are sown in the winter and harvested from spring to summer. "

  The varieties are broadly divided into Western and Eastern varieties. Furthermore, Western varieties are classified into 5 and 3 dimensional varieties such as Danvers, Long Orange, and Oriental varieties such as Kinki. The main lineage varieties are carrots corresponding to the 5 inch group of the Western system. 5 inch carrots include, for example, “Kuroda 5”, “Kouyo 2”, “Shin Kuroda 5”, “Shunjin Kinko 5”, “Yangming 5”, “Crimson 5”, “Yangzhou 5”, “Chiba There are varieties such as “5 inch”.

  Therefore, as a result of examining how carrot growth period and ripeness are related to freezing suitability, in the test using the most important varieties of 5-inch carrots currently produced in Japan, It was found that frozen carrots having a good texture can be produced by using fresh ones that are harvested within one month after the average root weight exceeds 100 g.

  In addition, as a point to be noted for each cropping type, when autumn and winter carrots have a long cultivation period, depending on the cultivation area, the cold season begins, and the surface of the ground where the carrots are cultivated falls below freezing point. In such a case, there is a risk that the carrots freeze and the refrigerating suitability is significantly reduced. Therefore, in an area where the temperature drops below freezing point, it is desirable to use what is harvested within one month after the average root weight exceeds 100 g and before the cold season. On the other hand, in the case of spring and summer carrots, the carrots that tend to stand up tend to increase when the growing period is long, and the quality of the carrots and formation layers tends to decrease significantly. It is desirable to harvest within 1 month after exceeding 100g.

  Next, the inventors of the present application examined an evaluation method for the streaks of frozen carrots. We aimed to establish an evaluation method of “muscle” based on objective physical property values, without relying only on sensory evaluation. It was found that the parallel / vertical ratio of hardness and the extrusion drip rate by the penetration of the carrot sample described later agree very well with the sensory evaluation. Therefore, the evaluation based on the parallel / vertical ratio of the hardness due to the penetration was also adopted for the evaluation of the “stripeness” together with the sensory evaluation. Also in the following examples, the measurement was performed using the following hardness measurement method and penetration drip measurement method.

  In the present application, the parallel direction is a direction parallel to the carrot fibers, and the vertical direction is a direction perpendicular to the carrot fibers.

[Physical property evaluation method]
I. Method of measuring hardness by penetration
1 Preparation of sample for hardness measurement by penetration (a) Current product After cleaning, peel off with a thickness of 1-2mm, and remove the upper (head) about 1.5-2cm, the upper middle layer part is 1cm thick Cut into half and then cut into half moon or ginkgo, blanched for 2 minutes in 98 ° C boiling water with a weight ratio of carrot: water = 1: 9, cooled in cold water at 4 ° C for 3 minutes, drained After that, it was quickly frozen with -35 ° C air blast, packed in PE (polyethylene) bags, and stored frozen at -25 ° C for up to one week until the measurement date. At the time of measurement, the frozen carrot sample was poured into 98 ° C boiling water at a weight ratio of carrot: water = 1: 9 as it was, heated for 4 minutes, allowed to cool at room temperature for 10 minutes, and hardness by penetration A sample for measurement was used.

(B) Product of the present invention After washing, heated in 98 ° C. boiling water at a weight ratio of carrot: water = 1: 9 for 1 minute, immediately cooled in 4 ° C. cold water for 3 minutes, then 4 ppm 200 ppm hypochlorous acid It was immersed in acid sodium water for 10 minutes. Thereafter, after removing about 1.5 to 2 cm of the upper part (head) from the peeled piece having a thickness of 1 to 2 mm, the upper middle layer was cut into 1 cm thicknesses, and further cut into half-moons or ginkgo. Immerse in 100ppm sodium hypochlorite water at 4 ° C for 10 minutes, then wash with water at 4 ° C, drain and quickly freeze with -35 ° C air blast, wrap in PE (polyethylene) bags, and until the measurement date Stored frozen at -25 ° C for up to 1 week. At the time of measurement, frozen carrot sample was poured into 98 ° C boiling water at a weight ratio of carrot: water = 1: 9, heated for 6 minutes, allowed to cool at room temperature for 10 minutes, and hardness by penetration A sample for measurement was used.

(C) Fresh products After washing, peel off at a thickness of 1 to 2 mm, and after removing about 1.5 to 2 cm from the upper part (head), cut the upper and middle layers into 1 cm thicknesses, and further cut into half-moon or ginkgo The sample was poured into 98 ° C. boiling water at a weight ratio of carrot: water = 1: 9, heated for 6 minutes and then allowed to cool at room temperature for 10 minutes to obtain a sample for measuring hardness by penetration.

2 Measuring equipment and measuring conditions As a measuring equipment, use a digital display force gauge (IMADA, DPSII-R, maximum load 19.6N (2kgf), display unit 0.01N (1gf). The handle was lowered at a speed of one rotation of the handle (feed of 10 mm) in 2 seconds.

3 Measuring method First, measure the maximum load value (parallel maximum load value) at the time of penetration in the parallel direction at the center part of the sieve part where there is no streak running horizontally toward the skin, and then do not apply to the previous penetration hole. Measure the maximum load value (vertical maximum load value) when the part is cut in parallel with a width of 1 cm and then penetrated from the direction perpendicular to the cut surface, that is, the fiber direction, and the ratio of these maximum load values (hereinafter referred to as parallel) / Denoted as vertical ratio).
This value indicates that the streaks increase as the value decreases.

II. Method for measuring pressure drip 1 Preparation of sample for measurement of pressure drip A sample for measurement of pressure drip was prepared by the following method from the same individual as the carrot solid used for the above-mentioned measurement of hardness by penetration.

(A) Current product After cleaning, peel off at a thickness of 1 to 2 mm, and after removing the upper (head) approximately 1.5 to 2 mm, cut the upper and middle layers into 1 cm thicknesses, and further center the center line of the wheel cut The line was cut in parallel at a width of 1 cm. After removing 1 to 2 mm of the skin part, the sieving part is 10 mm thick toward the center part (the maximum thickness if the sieving part is less than 10 mm), and the carrot: water = 1: 9 Branch for 2 minutes in 98 ° C boiling water by weight, cool in cold water at 4 ° C for 3 minutes, drain quickly, freeze at -35 ° C, put in PE (polyethylene) bag, measurement day (maximum 1 week) Stored frozen at -25 ° C. This sample was put into 98 ° C. boiling water having a weight ratio of carrot: water = 1: 9, heated for 4 minutes, allowed to cool at room temperature for 10 minutes, and then used as a sample for measuring pressure drip.

(B) Product of the present invention After washing, heat in 98 ° C. boiling water for 1 minute, immediately cool in 4 ° C. cold water for 3 minutes, immerse in 200 ppm sodium hypochlorite water at 4 ° C. for 10 minutes, After removing approximately 1.5-2 cm of the upper part (head) from the peeled surface with a thickness of ˜2 mm, the upper and middle layers were cut into 1 cm thicknesses, and further paralleled with a 1 cm width with the center line of the ring cut as the center line . A 10mm-thick sieving part towards the center (or smaller if the sieving part is less than 10mm) is cut in parallel and immersed in 100ppm sodium hypochlorite water at 4 ° C for 10 minutes. Thereafter, it was washed with water at 4 ° C., drained, quickly frozen at −35 ° C., placed in a PE (polyethylene) bag, and stored frozen at −25 ° C. until the measurement date (up to 1 week). This sample was put into 98 ° C. boiling water having a weight ratio of carrot: water = 1: 9, heated for 6 minutes, allowed to cool at room temperature for 10 minutes, and then used as a sample for measuring pressure drip.

(C) Fresh products After washing, peel off at a thickness of 1 to 2 mm, and after removing the upper (head) approximately 1.5 to 2 mm, cut the upper and middle layers into 1 cm thicknesses and further center the center line The line was cut in parallel at a width of 1 cm. To the center, the sieve part is 10mm thick (or smaller if the sieve part is less than 10mm) and cut in parallel, carrot: water = 1: 9 weight ratio of 98 ° C boiling water The sample was heated for 6 minutes and allowed to cool at room temperature for 10 minutes.

2 Measuring equipment and measurement conditions For drip measurement, sandwich the sample from above and below with a micrometer (Mitutoyo Co., Ltd., standard outside micrometer 101 series M210-25, measuring range 0-25mm, minimum graduation 0.01mm) For the purpose, a 50φ (mm) acrylic plate was fixed on the lower side and adjusted so that the upper side could be placed directly above the sample later.

3 Measuring method First, weigh the sample accurately before pressurization to obtain the weight before pressurization.
Next, the filter paper (Toyo Roshi, No. 5A, 50φ), the sample, the filter paper (Toyo Roshi, No. 5A, 50φ), and the presser acrylic plate from above are set in this order on the lower acrylic plate. Start turning the ratchet screw, the spindle touches the presser acrylic plate above the sample, starts ticking and idling, then turns 20 more times and then stops. Hold in this state for 1 minute, turn the ratchet in the reverse direction, and remove the sample after drip discharge.

This process was repeated for 10 pieces, and each of the 10 pieces was sampled accurately after being squeezed out to obtain a weight after pressurization.
The drip rate is calculated by drip rate = (weight before pressing−weight after pressing) / weight before pressing × 100.

III. Sensory evaluation of carrot The sensory evaluation of the carrot's muscularity (straightness, color, comprehensive evaluation) was performed by seven panelists based on the following criteria, and the score was expressed as an average score.
(1) Evaluation criteria for streaks:
Streaky ... 1 point, slightly streaky ... 2 points, neither can be said ... 3 points or slightly streaky ... 4 points, not streaky ... 5 points (2) Color Evaluation Criteria Bad ... 1 point, a little bad ... 2 points, neither can be said ... 3 points,
Slightly good ··· 4 points, good · · 5 points (3) Evaluation criteria for overall evaluation is bad · · 1 point, somewhat bad · · 2 points, neither can be said · · 3 points,
Slightly good 4 points, good 5 points

[Example 1] Skin freezing method after surface heat sterilization, raw freezing method Fresh autumn and winter carrots (Kouyo No.2, Chiba, 19 weeks after sowing, ML size) washed with water, 10 times the amount of carrots Soaked in 98 ° C water for 1 minute. After cooling in 4 ° C water for 3 minutes, it was immersed in 200 ppm sodium hypochlorite water at 4 ° C for 10 minutes. Peeled with a peeler, cut 1 cm above and below, cut 1 cm thick ginkgo, soaked in 100 ppm sodium hypochlorite water at 4 ° C for 10 minutes, washed with water at 4 ° C, drained -35 Quick frozen at ℃. After freezing, it was put in a PE (polyethylene) bag, stored at −25 ° C. for 1 week, and then boiled and thawed in boiling water 10 times the amount of carrot for 6 minutes to obtain Product 1 of the present invention.
[Comparative Example 1]

Method of freezing without surface heat sterilization Fresh autumn and winter carrots (Kouyo No.2, Chiba, 19 weeks after sowing, ML size) were washed with water and washed with 200ppm sodium hypochlorite water at 4 ℃. Immerse for a minute. Peeled with a peeler, cut 1 cm above and below, cut 1 cm thick ginkgo, soaked in 100 ppm sodium hypochlorite water at 4 ° C for 10 minutes, washed with water at 4 ° C, drained -35 Quick frozen at ℃. After freezing, it was put in a PE (polyethylene) bag and stored at −25 ° C. for 1 week to obtain Comparative Example 1.
[Comparative Example 2]

Branching method Fresh autumn and winter carrots (Kouyo No.2, Chiba, 19 weeks after sowing, ML size) washed with water, peeled with a peeler, cut 1 cm above and below, and cut into 1 cm thick ginkgo The product was blanched for 2 minutes in 98 ° C hot water, 10 times the amount of carrot, cooled in 4 ° C water for 3 minutes, and snap frozen at -35 ° C. After freezing, it was put in a PE (polyethylene) bag, stored at −25 ° C. for 1 week, boiled for 4 minutes in boiling water of 10 times the amount of carrot, and used as Comparative Example 2.
[Comparative Example 3]

Fresh products Fresh autumn and winter carrots (Kouyo No.2, Chiba, 19 weeks after sowing, ML size) washed with water, peeled with a peeler, cut 1 cm above and below, and cut into 1 cm thick ginkgo It was boiled in boiling water 10 times the amount of carrot for 6 minutes to make Comparative Example 3.

  In both the product 1 of the present invention and the comparative example 1, carrots in a frozen state before thawing were measured. The definitions of bacteria (viable), coliforms, and E. coli shown here were based on the Food Sanitation Law, and the inspection was conducted by an official method.

  In the case of Comparative Example 1 in which surface heat sterilization is not performed, the number of general viable bacteria is relatively large, and the coliform group is also positive. In comparison, in the case of the product 1 of the present invention subjected to surface heat sterilization, the number of general viable bacteria was small, the coliform group was negative, and no microbiological problems were observed.

  In the case of Comparative Example 2 (branching method), the parallel / perpendicular ratio is low, the drip rate is high, and in any of the straightness, color, and overall evaluation of the sensory evaluation items, compared with the product 1 of the present invention, The quality was bad. The product 1 of the present invention showed no significant difference from Comparative Example 3 (fresh product) in any item, indicating that the texture was close to that of fresh product.

Claims (7)

A method for producing frozen carrots , comprising heating at 90 to 100 ° C. for 30 seconds to 2 minutes, heating with heated water, a heated aqueous solution or heated steam, followed by freezing.   The method according to claim 1, wherein after the skin is peeled, it is cut and then frozen.   The method according to claim 1 or 2, wherein the surface of the carrot is washed before heating. The method according to any one of claims 1 to 3 , wherein the carrot is peeled at a thickness of 1 to 2 mm. The method for producing frozen carrots according to any one of claims 1 to 4 , wherein the carrot is a Western 5-sized carrot and uses carrots harvested within one month after the average root weight exceeds 100 g. The frozen carrot manufactured by the method of any one of Claims 1-5 . A cooked food comprising the frozen carrot according to claim 6 .