JP7778049B2 - Method for producing washed baby leaves and method for reducing the number of bacteria in washed baby leaves - Google Patents

Description

The present invention relates to a method for producing washed baby leaves and a method for reducing the number of bacteria in washed baby leaves.

In recent years, ready-to-eat vegetables have become increasingly popular, such as bagged or cupped leafy vegetables, cut vegetables, salads, etc. This is because these products are already washed and sterilized, eliminating the need for additional cleaning.

However, there are various problems with ready-to-eat vegetables, specifically the difficulty of disposing of unsold items, controlling orders, etc. The cause of these problems is that ready-to-eat vegetables are fresh foods and therefore have a short shelf life.

Therefore, technologies have been developed to improve the expiration date of ready-to-eat vegetables, examples of which are as follows: Patent Document 1 discloses a method for preserving cut vegetables, specifically, by applying a sterilizing solution to the cut vegetables before storing them and then rinsing them with water.

Patent Document 2 discloses a method for producing leafy vegetables, specifically, a sterilizing solution is applied to the leaves before storing them, and after further application of the sterilizing solution, the leaves are washed with water.

Japanese Patent Application Laid-Open No. 2004-65149 Japanese Patent Application Laid-Open No. 2008-237208

The problem to be solved by the present invention is to reduce the number of bacteria on washed baby leaves.

Baby leaves generally have high bacterial counts after harvest and storage, so it is important to reduce the bacterial count when producing washed baby leaves.
Because it is a fresh food, heat sterilization is not recommended, and washing is an important process for reducing the number of bacteria.

In order to solve this problem, the present inventors have conducted extensive research and discovered the relationship between the moisture adhesion rate of baby leaves and the effect of reducing the number of bacteria after washing. From this perspective, the present invention can be defined as follows.

The method for producing washed baby leaves according to the present invention comprises at least washing. The baby leaves to be washed here are baby leaves, and the moisture adhesion rate of the baby leaves is 1
.0% or less.

The method for producing washed baby leaves according to the present invention comprises at least dewatering and washing. Here, what is removed is the water adhering to the baby leaves, and what is washed is the baby leaves from which the water has been removed.

In addition, it is preferable that the moisture adhesion rate of the baby leaves obtained by dehydration is 1.0% or less, and dehydration is preferably carried out by drying the baby leaves after harvesting or by using a moisture-absorbing packaging material when transporting the baby leaves after harvesting.

The cleaning solution used for cleaning preferably contains at least hypochlorous acid or hypochlorite, and the number of bacteria on the baby leaves obtained by dewatering and cleaning is as follows:
It is preferably 1.0×10 ⁵ CFU/g or less.

Furthermore, the temperature range for distribution of washed baby leaves produced by this production method is chilled, and the general viable bacterial count of the washed baby leaves produced 24 hours after production is 1.
Preferably it is less than 0×10 ⁶ CFU/g.

The method for reducing the number of bacteria in washed baby leaves according to the present invention comprises at least washing. Here, baby leaves are washed, and the baby leaves have a moisture adhesion rate of 1.0% or less. The method for reducing the number of bacteria in washed baby leaves according to the present invention comprises at least dewatering and washing. Here, what is removed is the water adhering to the baby leaves, and what is washed is the baby leaves from which the water has been removed.

In addition, it is preferable that the moisture adhesion rate of the baby leaves obtained by dehydration is 1.0% or less, and dehydration is preferably carried out by drying the baby leaves after harvesting or by using a moisture-absorbing packaging material when transporting the baby leaves after harvesting.

The cleaning solution used for cleaning preferably contains at least hypochlorous acid or hypochlorite, and the number of bacteria on the baby leaves obtained by removing water and cleaning is as follows:
It is preferably 1.0×10 ⁵ CFU/g or less.

Furthermore, the temperature range for distribution of the washed baby leaves obtained by this method is chilled, and the general viable bacterial count of the washed baby leaves obtained by this method 24 hours after production is preferably less than 1.0 x 10 ⁶ CFU/g.

The mechanism by which the effects of the present invention are obtained is presumed to be as follows: By reducing the moisture on the surface of baby leaves before washing them, the cleaning solution with bactericidal effect can more easily penetrate into the leaves, thereby enhancing the bactericidal effect.

The present invention makes it possible to enhance the effect of reducing the number of bacteria when washing baby leaves. By reducing the number of bacteria in baby leaves, the shelf life of washed baby leaves can be improved. Such washed baby leaves can be eaten without further washing.

1 is a flow chart showing a method for producing washed baby leaves according to the present embodiment. Difference in bacterial count after washing with or without dewatering

<Baby leaf>
Baby leaf refers to leafy vegetables that are about 10 to 90 days old after sowing. In the present application, when the term "baby leaf" is used, it does not matter whether the type of baby leaf is singular or plural, and specifically, it may refer to one type of baby leaf or a mix of several types of baby leaf. The size of baby leaf varies depending on the type of plant and is not limited, but from the perspective of ease of eating, it is 4 cm or more and 15 cm or less, preferably 12 cm or less, and more preferably 10 cm or less.

Plants used for baby leaves are not particularly limited as long as they are edible, but examples include vegetables of the Brassicaceae, Amaranthaceae, Asteraceae, Umbelliferae, Liliaceae, and Chenopodiaceae families. Specific examples include sunny lettuce, green curl, lettuce, mizuna, beet, mustard greens, green mustard, arugula, spinach, red takana, romaine, red oak, tatsoi,
These include Xiaohongcai, Lollo Rossa, Red Asian Mustard, Pinot Green, White Kale, Red Kale, Detroit, and Pak Choi.

<Containerized salad>
The containerized salad according to the present invention (hereinafter referred to as "containerized salad") refers to a salad that is packaged and contains at least washed baby leaves. The temperature range in which the containerized salad is distributed is preferably the so-called chilled (refrigerated) range. The chilled range is a distribution temperature range of 10°C or below where the salad does not freeze. The chilled range is preferably 0°C to 10°C, and more preferably 0°C to 5°C.

<Method of manufacturing washed baby leaves>
Figure 1 shows the flow of the manufacturing method of washed baby leaves. This manufacturing method of baby leaves mainly consists of cultivation, harvesting (S10), transportation (S20), sorting (S30),
The process includes dewatering (S40), washing (S50), soaking (S60), spin-drying or drying (S70), and packaging (S80).

<Cultivation and Harvesting (S10)>
The method for cultivating baby leaves is not particularly limited, and examples include hydroponic cultivation, soil cultivation, cultivation in the open field, and cultivation in a closed plant factory. Hydroponic cultivation has the advantage of being less affected by weather and less susceptible to bacterial adhesion. Cultivation in a closed plant factory is also preferable from the standpoint of hygiene and stable production. The method for cultivating and producing baby leaves described herein is the content described in JP 2017-060441 A.

The baby leaves thus cultivated are harvested by any method, including but not limited to manual harvesting, mechanical harvesting, or a combination thereof.

<Transportation (S20)>
One of the purposes of transporting harvested baby leaves is to wash them. The method of transportation is not particularly limited, and may be, for example, containerized, bagged, or packed in cardboard boxes. However, from the viewpoint of reducing the moisture content of baby leaves, it is preferable to pack them in a packaging material with a dehumidifying effect during transportation. This can be used as an alternative to the water removal process described below. It also enhances the bacterial count reduction effect during washing, described below.

<Sorting (S30)>
The criterion for sorting baby leaves is whether they are damaged or not. Damaged means that the baby leaves (leaves and petioles) are broken, chipped, or torn, and the internal tissue structure of the leaves is damaged. Some baby leaves may not look good. Removing damaged baby leaves improves the appearance of the final product.

<Water removal (S40)>
The purpose of dehydrating baby leaves is to enhance the bacterial count reduction effect during washing, which will be described later. For this purpose, dehydration should be performed before washing. The method of dehydration is not particularly limited, and includes leaving the leaves to stand, blowing air, cold air, hot air, centrifugation, vacuum suction, and the use of moisture-absorbing materials, or a combination of these. Dehydration can also be achieved during transportation by using a dehumidifying material in the packaging. The target for dehydration is not particularly limited, but is preferably a moisture adhesion rate of 1.0% or less. This enhances the bacterial count reduction effect of washing.

<Cleaning (S50)>
The purpose of washing baby leaves is to remove foreign matter and reduce the number of bacteria. Examples of foreign matter include mud, soil, sand, etc. that adhere to baby leaves. The means for washing baby leaves is not particularly limited, but preferably involves contact with sterilized water. The method of contact is not particularly limited, but examples include immersion, spraying, etc. Baby leaves are washed once or twice or more times. The effect of the solution used for washing is to reduce the general viable bacterial count. Such washing solutions are not particularly limited, but examples include hypochlorous acid, hypochlorite, chlorite, sodium hydroxide, potassium hydroxide, calcined calcium, hydrochloric acid, acetic acid, peracetic acid, citric acid, fumaric acid, ozone, etc., with hypochlorous acid, hypochlorite, and chlorite being preferred. Preferred conditions for hypochlorous acid, hypochlorite, and chlorite are concentrations of 10 to 200 pmol/L.
The pH is preferably 4.8 to 8.0, and more preferably 5.0 to 7.0. These factors enhance the effect of reducing the number of bacteria.

<Wetted temperature>
When contacting the sterilizing water, the temperature of the sterilizing water is 0°C to 30°C, preferably 0°C to 20°C, more preferably 0°C to 15°C, and most preferably
The temperature range is 0 to 10°C. If the temperature of the sterilizing water is too high or too low, it will cause significant damage to the baby leaves. For example, they will be more likely to absorb the odor of the sterilizing water, they will be more likely to wilt, and they will not keep as long.

<Liquid contact time>
The contact time is not particularly limited, but is 10 seconds to 60 minutes, preferably 10 seconds to 15 minutes, and most preferably 10 seconds to 10 minutes. If the contact time with the sterilized water is too short, it is difficult to reduce the general viable cell count. On the other hand, if the contact time is too long, damage to the baby leaves will be significant.

<Water soaking (S60)>
The purpose of soaking baby leaves in water is to remove the disinfectant. That is, soaking in water is required when the leaves are exposed to sterilized water. In other words, this step is omitted as appropriate. The means of soaking in water is not particularly limited, but preferably includes immersion in water, spraying with water, etc.

<Soaking water>
The water for soaking is not particularly limited, but may be, for example, tap water, well water, purified water, etc. In addition, chlorine contained in water that has undergone necessary sanitary measures (see Enforcement Regulations of the Water Supply Act (Ministry of Health and Welfare Ordinance No. 45 of December 14, 1957)) is not subject to removal during soaking.

<Water soaking temperature>
The temperature for soaking in water is 0° C. to 30° C., preferably 0° C. to 20° C., and most preferably 0° C. to 10° C. If the temperature for soaking in water is too high or too low, the baby leaves will be significantly damaged.

<Water soaking time>
The time for soaking in water is not particularly limited, but is preferably 1 second to 60 minutes, more preferably 5 seconds to 30 minutes, and most preferably 10 seconds to 10 minutes.
If the soaking time is too short, the fungicide removal effect will be reduced, while if the soaking time is too long, the damage to the baby leaves will be significant.

<Dehydration or Drying (S70)>
The purpose of dehydrating or drying washed baby leaves is to improve the appearance of the baby leaves after washing. The dehydration or drying method is not particularly limited, and may be standing, blowing air, cold air, hot air, centrifugation, vacuum suction, the use of moisture-absorbing materials, or a combination thereof. Considering damage caused by contact between baby leaves and damage caused by pressure due to centrifugation, it is preferable to avoid centrifugation and dry by blowing air. The target for water removal is not particularly limited, but preferably the moisture adhesion rate is 3.0% or less. Details of the moisture adhesion rate will be described later.

<Packaging in containers (S80)>
The baby leaves are packed in containers. The packaging material used for packing the leaves into containers is not particularly limited, but may be a polyethylene bag, a cup, or the like.

<Moisture adhesion rate>
The moisture adhesion rate of baby leaves is the value obtained by dividing the amount of moisture attached to the leaves by the weight of the leaves after the moisture has been removed, and multiplying the result by 100. The specific method for measuring the moisture adhesion rate is as follows: The weight (A) of the leaves with moisture attached is measured. Then, the moisture attached to the leaves is wiped off with moisture-absorbing paper or the like, and the weight (B) of the leaves after the moisture has been removed is measured. The moisture adhesion rate can be calculated using the following formula:
Moisture adhesion rate (%) = 100 x (A - B) / B
<Number of bacteria>
The number of bacteria in the baby leaves measured is the general viable bacterial count. The method for measuring the general viable bacterial count is as follows:
Any known method may be used, and specifically, the Food Sanitation Inspection Guidelines (Japan Food Sanitation Association, 2014)
This is a pour plate method using a standard agar medium in accordance with the Japanese Industrial Standards (JIS No. 2004). Washing (S50) can reduce the viable bacterial count by 1.0 to 3.0 orders of magnitude. The viable bacterial count after washing (S50) is preferably 1.0 x 10 ⁴ to 1.0 x 10 ⁵ CFU/g. The viable bacterial count after 24 hours from the production of washed baby leaves is preferably 1.0 x 10 ⁶ CFU/g.
The preferred general viable cell count after 72 hours from the production of washed baby leaves is 1.0×10 ⁶ CFU/g or less, more preferably 1.0×10 ⁵ CFU/g or less.
FU/g or less. This allows the food to be eaten without washing afterwards. In addition, according to the hygiene standards for boxed lunches and prepared dishes (Kanshoku No. 161, June 29, 1979, amended by Eishoku No. 188, Eiryu No. 211, and Eika No. 119, October 12, 1995),
The general viable cell count is 1.0×10 ⁶ CFU/g or less.

The baby leaf according to the present invention is embodied in Example 1. However, the scope of the claims according to the present invention is not limited to these Examples.

<Baby leaf>
The baby leaves used in this example were a mixture of pinot noir, spinach, beet, and arugula.

<Measurement of bacterial count>
The measurement of the number of bacteria in this measurement is based on the Food Sanitation Inspection Guidelines (Japan Food Sanitation Association, 200
The procedure was carried out in accordance with the 4th year.

<Comparative Example 1>
In Comparative Example 1, the baby leaves after harvesting were packed into bags, placed in plastic containers, and transported to a factory. After sorting, they were washed with washing water containing hypochlorous acid, soaked in water, and then dried by exposing them to air. The moisture adhesion rate was measured before washing, and the number of bacteria was measured before washing, after drying, and 72 hours after drying.

Example 1
In Example 1, the baby leaves were washed, soaked in water, and dried in air under the same conditions as in Comparative Example 1 after harvesting, except that they were packed into bags, placed in cardboard boxes with the bags open, and transported to the factory. The moisture adhesion rate was measured before washing, and the bacterial count was measured before washing, after drying, and 72 hours after drying. The test was conducted under the same conditions as in Comparative Example 1, except that cardboard boxes were used for transportation.

<Evaluation results, summary>
Taking the above test results into consideration, it was found that the rate of moisture adhesion to the surface of baby leaves was reduced by using hygroscopic cardboard packaging instead of containers during transportation after harvest. Then, by sterilizing this with washing water that has a bactericidal effect, the effect of reducing the number of bacteria was enhanced.
Even 72 hours after production, the bacterial counts of the washed baby leaves remained low compared to the section transported in containers.

This shows that reducing the moisture adhesion rate on the surface of baby leaves, especially reducing the moisture adhesion rate to 1.0 or less, increases the effect of reducing the number of bacteria during washing. It has also been found that the use of the method of the present invention can extend the shelf life of the leaves.

The field in which the present invention is useful is a method for producing washed baby leaves and a method for reducing the number of bacteria in washed baby leaves.

Claims (2)

A method for producing baby leaves, comprising at least the following steps:
Harvesting: The harvested leaves are baby leaves, and
Packaging: The baby leaves are harvested and packed in moisture-absorbing packaging.
Transportation: The baby leaves are packed and are transported to the cleaning process.
The moisture adhesion rate of the transported baby leaves is 1.0% or less,
Washing: It is the transported baby leaves that are washed. The method of claim 1,
The moisture-absorbing packaging material is cardboard.