A method for producing frozen vegetables that are heat-sterilized before freezing and consumed without heating after thawing.

Abstract

Medical meals (meals for inpatients and residents in medical facilities, nursing and welfare facilities, etc.), especially hospital meals, can only provide warm vegetable salads and cannot serve raw vegetable salads. In addition, conventional frozen vegetables have undergone enzyme inactivation by blanching, resulting in poor texture and unappetizing taste. 【Solution】Wash, cut the harvested vegetables, and during heat sterilization, perform low-temperature sterilization that meets the conditions for killing coliform bacteria and does not aim at enzyme inactivation, then cool and freeze them. The resulting frozen vegetables can be consumed without heating after thawing, enabling a taste and texture close to fresh produce.

Description

Technical Field

[0001] The present invention relates to frozen vegetables that are heat-sterilized before freezing and consumed without heating after thawing, and methods for producing the same.

Background Art

[0002] Conventional frozen vegetables are those in which, after cutting the vegetables, blanching is performed for the purpose of inactivating the enzymes in the vegetables, and at the same time, achieving the killing of Escherichia coli or the killing of coliforms or the killing of both Escherichia coli and coliforms, followed by cooling and freezing. Blanching is mainly a processing method in which vegetables, fruits, etc. are heated for a short time and then cooled. It is often carried out as a pretreatment for frozen vegetables. Most frozen vegetables are soaked in boiling water or exposed to steam before rapid freezing and are heated to 70 - 80% of the cooking heat. The main purpose of blanching is to inactivate enzymes that cause changes in color, texture, and aroma. Enzymes that cause deterioration of the quality of vegetables and fruits include lipoxygenase, polyphenol oxidase (English version), polygalacturonase (English version), chlorophyllase (English version), etc. When verifying the effect of blanching, catalase and peroxidase, which are highly resistant to heat, are often used. There is also the purpose of softening the tissue to prevent tissue damage due to freezing. There are also effects such as preventing changes in color and aroma, preventing changes in nutrients, removing residual pesticides, etc., and reducing harmful microorganisms. Disadvantages include the loss of water-soluble or heat-sensitive nutrients and the generation of wastewater.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

[0004]

Patent Document 2

[0005] When frozen vegetables produced by the method described in the section of "Background Art" achieve only enzyme inactivation and Escherichia coli killing conditions by blanching, they must be heated and consumed after thawing. When enzyme inactivation, Escherichia coli, and coliform group killing conditions are achieved, and when only coliform group killing conditions are achieved, they can be consumed without heating after thawing. When the enzyme is inactivated, the texture deteriorates and it is not delicious. Normal sterilization is performed with hot water at around 100 degrees (95 to 100 °C). When trying to achieve coliform group killing conditions under these conditions, the enzyme is inactivated. Also, since it is directly in contact with hot water, umami components and nutrients leak out.

[0006] According to the Mass Cooking Manual (revised on June 16, 2017), When serving vegetables and fruits, heating or disinfection is essential. Therefore, in medical meals (meals for inpatients and residents in medical facilities, nursing and welfare facilities, etc.), especially in hospital meals, only heated vegetable salads can be provided, and for patients who cannot eat raw vegetable salads, cooks are providing warm vegetable salads. Generally, in medical meals, only warm vegetable salads are served, and warm vegetable salads have a poor texture and are not delicious.

Summary of the Invention

[0007] An object of the present invention is to provide, as a medical salad, frozen vegetables that can be stored for a long time compared to fresh cut vegetables, etc., and that can be eaten as they are (without heating) after thawing, have a good taste, a good texture, and are delicious, and are sterilized frozen vegetables.

Means for Solving the Problems

[0008] An object of the present invention is to consume frozen vegetables without heating after thawing, without making enzyme inactivation the purpose of blanching. By controlling microbial management, heating conditions, and cooling conditions, a non-heated intake product can be produced. Regarding microbial management Standard for frozen foods (from the Ministry of Health, Labour and Welfare website) (1) Non-heated intake frozen foods (among frozen foods, those that are manufactured or processed and then frozen, and are considered not to require heating when served for eating) must have a bacterial count (total viable count) of 100,000 or less per gram of the sample, and the coliform group must be negative. (2) Frozen foods for intake after heating must have a bacterial count (total viable count) of 3,000,000 or less per gram of the sample, and Escherichia coli must be negative.

[0009] Conventional methods for manufacturing frozen vegetables involve cutting the vegetables and performing blanching for the purpose of inactivating enzymes. In this case, the inactivation of enzymes, the reduction of Escherichia coli and the coliform group, and rapid freezing are carried out to produce the product. In the present invention, the purpose of blanching is divided into two: enzyme inactivation and coliform group killing conditions. The purpose is narrowed down to good palatability, and only the killing of the coliform group is achieved under heating conditions of low temperature and short time. Therefore, even in the frozen state, browning of the vegetables progresses, so productization is achieved by setting a short shelf life. If the coliform group killing conditions (central temperature 75°C for 1 minute or more) are satisfied, it can be eaten without heating after thawing. Definition of terms Medical salad: Frozen vegetables that can be stored for a long time compared to fresh cut vegetables, etc., but can be eaten as they are (without heating) after thawing, with good taste, texture, and delicious, sterilized frozen vegetables Heat-resistant and cold-resistant bag: A bag for putting ingredients, which can be used for heat sterilization and freezing. IQF: Refers to INDIVIDUAL QUICK FROZEN. It means rapid individual freezing.

Brief description of the drawings

[0010] Experiment ▲1▼ Fresh cabbages were shredded (3×3×30 - 50 mm), 200 g were filled into heat-resistant and cold-resistant bags, Vacuum package, TIFF0007690706000001.tif10100 and perform heating, Install a button thermometer (Rh manager) with a diameter of about 1 cm at the center of the cabbage, and perform measurement. After the central temperature of the cabbage reaches 75 °C, Measure the residual enzymes in the cabbage at 1 minute, 2 minutes, 3 minutes, and 4 minutes. In this experiment, since heating is performed at a constant temperature of 80 °C, the central temperature does not exceed 80 °C. For the measurement method of residual enzymes, the "Peroxidase Activity Measurement Method" was used. There are many types of enzymes, but here, the activity of peroxidase, which is heat-resistant, will be measured. First, collect 5 g of the sample (shredded cabbage) and control the temperature to room temperature. Use a knife to finely chop the 5 g sample and put it into a test tube. Add 1 ml of 1% guaiacol dilution, 1 ml of 0.5% hydrogen peroxide dilution, and 5 ml of distilled water to the test tube respectively, and stir. Completely mix the sample and the reagent in the test tube. Add the reagent. If there is a change to brown after 2 minutes, it is judged that the enzyme remains. If there is no change, it is judged that the enzyme has been inactivated. Result: No inactivation of the enzyme was confirmed at any time. When the measurement was carried out until 13 minutes, the enzyme did not inactivate. Experiment ▲2▼ Cut fresh cabbage into pieces (3×3×30 - 50 mm), TIFF0007690706000002.tif10116 and perform heating, After putting the cabbage into hot water, Measure the residual enzymes in the cabbage at 1 minute, 2 minutes, 3 minutes, and 4 minutes. The measurement method of residual enzymes is the same as that in Experiment ▲1▼. Result: No inactivation of the enzyme was confirmed at any time.

Example 1

[0011] The shredded cabbages, Chinese cabbages, Komatsuna, and daikon leaves produced by the present invention are produced by the production method described below. The harvested cabbages, Chinese cabbages, Komatsuna, and daikon leaves are visually sorted, washed, cut into pieces of 3×20 - 50 mm, washed again, immersed in an aqueous sodium hypochlorite solution with a concentration of 100 ppm for 10 minutes for sterilization, then washed, and dehydrated in a dehydrator for 60 seconds. The dehydrated vegetables are filled into heat - resistant and cold - resistant bags at 500 g per bag and vacuum - packed. The vacuum - packed vegetables are sterilized (at 92°C for 10 minutes), and subjected to boiling heat sterilization that satisfies the coliform death condition (75°C for 1 minute or more) at the central temperature of the vegetables. After heat sterilization, cooling is carried out with running water (water temperature 10°C or lower), and the vegetables that are rapidly frozen (at - 30°C) are used as frozen shredded cabbages, Chinese cabbages, Komatsuna, and daikon leaves.

Example 2

[0012] The shredded cabbages, Chinese cabbages, Komatsuna, and daikon leaves produced by the present invention are produced by the production method described below. The harvested cabbages, Chinese cabbages, Komatsuna, and daikon leaves are visually sorted, washed, cut into pieces of 3×20 - 50 mm, washed again, immersed in an aqueous sodium hypochlorite solution with a concentration of 100 ppm for 10 minutes for sterilization, then washed, and dehydrated in a dehydrator for 60 seconds. The dehydrated vegetables are filled into heat - resistant and cold - resistant bags compatible with a microwave oven and vacuum - packed. The vacuum - packed vegetables are sterilized (at 92°C for 10 minutes), and subjected to boiling heat sterilization that satisfies the coliform death condition (75°C for 1 minute or more) at the central temperature of the vegetables. After heat sterilization, cooling is carried out with running water (water temperature 10°C or lower), and the vegetables that are rapidly frozen (at - 30°C) are used as frozen shredded cabbages, Chinese cabbages, Komatsuna, and daikon leaves. The heat- and cold-resistant microwave-compatible bag heats the filled vegetables by microwave while in a sealed or semi-sealed state. The frozen vegetables heated inside the microwave bag generate steam due to the moisture of the thawed vegetables, and the steam is appropriately leaked at the pressure release mechanism 25 or the above-mentioned vent hole. By heating using such steam, the thawed vegetables are cooked into warm vegetables. Measurement of Browning Caused by Residual Enzymes in Experimental ▲3▼ Vegetables Fresh leafy vegetables (Chinese cabbage, cabbage, spinach, lettuce, green onion, onion, Komatsuna, turnip greens, butterbur, Mitsuba, chrysanthemum greens, Mizuna, celery, asparagus, cauliflower, broccoli, leek, garlic, daikon leaves) and root vegetables (daikon radish, carrot, potato, taro, turnip, burdock, lotus root, yam), and fruit vegetables (cucumber, eggplant, tomato, green pepper, pumpkin, sweet corn, green bean, green pea, green pea, edamame) were cut, washed, filled into heat- and cold-resistant bags, vacuum-packed, and based on the methods of Experiment ▲1▼ and Experiment ▲2▼, only coliform bacteria were sterilized without inactivating the enzymes, cooled, frozen, and stored at -18°C, and it was measured whether browning caused by residual enzymes occurred. In the case of Chingen vegetables, Komatsuna, and daikon leaves, browning caused by residual enzymes was observed within two weeks from the measurement, but it was still sellable. Four weeks from the measurement, the green leaf part became darker, and the color of the white stem part became darker. Since browning was observed in part of the leaves, it was considered unsellable. Regarding cabbage, no browning was observed even after 6 months had passed.

Claims

1. Harvested, washed, Cut into thin strips, Fresh Chinese cabbage, cabbage, spinach, lettuce, green onions, onions, komatsuna, bok choy, butterbur, mitsuba, chrysanthemum, mizuna, celery, asparagus, cauliflower, broccoli, chives, garlic, daikon leaves, daikon, carrots, potatoes, taro, turnips, burdock, lotus root, mountain yams, cucumbers, eggplants, bell peppers, pumpkins, green beans, and snow peas are packed in heat-resistant and cold-resistant bags and then vacuum-packed. Sterilized by heating with water or steam, The core temperature is 75°C to 80°C. Kills coliform bacteria, Does not inactivate the peroxidase enzyme. Quickly freeze, After thawing, Can be consumed without heating. How to make frozen vegetables.

2. Harvested, washed, Cut into thin strips, Fresh Chinese cabbage, cabbage, spinach, lettuce, green onions, onions, komatsuna, bok choy, butterbur, mitsuba, chrysanthemum, mizuna, celery, asparagus, cauliflower, broccoli, chives, garlic, daikon leaves, daikon, carrots, potatoes, taro, turnips, burdock, lotus root, mountain yams, cucumbers, eggplants, bell peppers, pumpkins, green beans, and snow peas are packed into heat-resistant and cold-resistant bags and then packed into microwave-safe bags, Vacuum packed, Sterilized by heating with water or steam, The core temperature is 75°C to 80°C. Kills coliform bacteria, Does not inactivate the peroxidase enzyme. Quickly freeze, After thawing, Can be consumed without heating. How to make frozen vegetables.

3. The heat sterilization is performed at 80 to 92°C. The core temperature is 75°C for 1 minute or more, which is the condition for killing coliform bacteria. In addition, the treatment is performed under conditions that do not aim at inactivating the peroxidase enzyme, so that the core temperature is kept at 80°C or less. The method for producing frozen vegetables according to claim 1 or 2.

4. 3. The method for producing frozen vegetables according to claim 1 or 2, wherein the expiration date is determined based on the change over time in browning caused by residual peroxidase enzyme.

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