JP2023175591A - Temperature time integration indicator - Google Patents

Abstract

To provide a temperature time integration indicator for determining deterioration state of a food product such as a perishable food or a box lunch in which quality deteriorates due to proliferation of microorganisms or the like or a product material which is sensitive to temperature, using a material harmless to food without a risk of contamination, and allowing easy visual recognition by a continuous display from the start of measurement.SOLUTION: Contacting a non-volatile or low volatile liquid with an adsorbent causes the adsorbent to start diffusing. A temperature time integration indicator features a continuous visual indication of quality deterioration of food and beverage caused by microorganisms or the like.SELECTED DRAWING: Figure 1

Description

The present invention relates to a temperature-time integration indicator that can display the temperature-time integration history by irreversible changes in color and scale, indicating how long a sample, such as food, has been exposed to temperatures that cause deterioration. .

The following reports have been made as an indicator for determining the deterioration status of foods or temperature-sensitive products whose quality deteriorates due to the growth of microorganisms, such as fresh foods and boxed lunches.
(a) Deterioration is indicated by the color development of the ink or reactant, which changes color depending on the rising temperature and time. (Patent Documents 1 to 11)
(a) Diffusible dye diffuses into the dye diffusion layer as the temperature rises and over time, and the dyeing shows the temperature history. (Patent Documents 12 to 15)
(c) A specific active agent layer is brought into contact with the microorganism, and the time-temperature history is indicated by a color change indicator or gas generation caused by the metabolism of the microorganism. (Patent Documents 16-17)
Japanese Unexamined Patent Publication No. 62-190467 Publication No. 197485, Showa 62-197485 Japanese Patent Application Publication No. 10-307192 Japanese Patent Application Publication No. 11-296086 Patent Publication No. 2003-511695 Japanese Patent Application Publication No. 11-14616 Japanese Patent Application Publication No. 5-99754 Japanese Patent Application Publication No. 5-126969 Japanese Patent Application Publication No. 2002-129139 Patent Publication No. 2012-514620 JP2019-43860A Patent Publication No. 2004-340671 Japanese Patent Application Publication No. 5-149797 Japanese Patent Application Publication No. 10-267761 Patent Publication No. 2008-516190 Patent Publication No. 2005-87044 Patent Publication No. 2007-525664

The conventional technology has the following drawbacks.
(A) Since this indicator should originally be attached to foods, etc., it is desirable to use materials that are safe even if they are mixed into foods.
In the case of (a) and (b), if the indicator or dye uses chemicals that are toxic and unsuitable for consumption, if the indicator is damaged and the contents are scattered, or if the attached food etc. It will become contaminated.
The same is true when microorganisms are used as in (c), and foods, etc. are contaminated with high concentrations of microorganisms. As for the type of microorganisms to be used, selecting microorganisms that actually cause corrosion may improve the accuracy of the indicator, but placing such microorganisms together with food may cause accidents. sell.
Even if the selection of microorganisms is replaced with yeast or lactic acid bacteria, which have relatively little effect on the human body, if there is damage, there will still be contamination, and if microbial testing is performed during quality inspection, the number of microorganisms will be excessive. This may lead to the product being judged as defective, and the taste and other quality may deteriorate or gas may be emitted.

(B) Conventionally, the deterioration status of a specimen could only be displayed in several discontinuous stages, or even if it was continuous, it was difficult to distinguish colors etc., and the deterioration status could not be clearly displayed. there were. In the case of methods that use microorganisms, the amount of gas generated and the color change of the indicator due to metabolism remain almost unchanged for a certain period of time after the reaction starts, and then the reaction progresses rapidly. It is difficult to judge how many hours remain until it is safe.

In order to overcome this problem, the present invention covers a color-coded display scale according to the degree of safety or a corresponding clearly distinguishable display scale on a paper, a thin layer or a thin film used as an adsorbent.
When a non-volatile or low-volatile liquid permeates the adsorbent, its transparency increases and the display scale underneath can be seen. The display scale is now visible.
For example, by color-coding the lower display scale so that safe areas are displayed in blue, caution areas are displayed in yellow, and dangerous areas are displayed in red, the degree of danger of the sample can be easily confirmed continuously on one display scale. It becomes possible.

A non-volatile or low volatility liquid will diffuse up the adsorbent at a greater rate as the temperature increases.
Furthermore, under the same conditions, reproducibility of the diffusion rate was confirmed.
Utilizing these two characteristics of diffusion rate and the property of the adsorbent whose transparency increases as liquid permeates therein, a temperature-time integration indicator with good reproducibility is provided.

In the following two points, effects not found in conventional products can be obtained.
(a) The present invention can be produced without using harmful substances.
For the adsorbent, display scale, and container, select substances that are not harmful to human consumption, or those that do not detect harmful substances in elution or leaching tests. If you choose one of these, even if the indicator is damaged due to an accident and its contents are scattered, the attached food etc. will not be contaminated with harmful substances or microorganisms and you can safely eat or use it.

(b) The temperature and time display of the adsorbent starts from the moment the partition with the non-volatile or low-volatile liquid is removed, and the temperature and time display continues continuously at any time until the limit display time is reached. It can be confirmed.
In addition, the display scale is divided by color, scale shape, etc. in order to display the degree of safety and risk, and the user can select from a number of methods that are easy to visually judge.

The basic structure of the present invention is as follows.
(a) Non-volatile liquid or low-volatility liquid (1) and container enclosing it (2)
(b) Adsorbent (3) with display scale and container to enclose it (4)
(c) a removable or openable partition (5) that interrupts the connection between (2) and (4);

The display scale support in the present invention is not particularly limited in terms of material, size, length, width, color, etc. The display scale support may be an adsorbent.

The display scale in the present invention is not limited to other conditions as long as it is not a component raw material that dissolves in the non-volatile liquid or low-volatility liquid used.
However, it is desirable that it is not a harmful substance.

The non-volatile liquid or low-volatile liquid in the present invention is preferably a food such as soybean oil, noodle oil, rapeseed oil, or olive oil, but other substances are liquid at room temperature and are non-volatile or As long as it has low volatility, there are no restrictions on what can produce that effect.
Further, there is no restriction at all as long as it has transparency to the extent that the display scale can be seen.
In the case of volatile liquids, they evaporate from the adsorbent, making accurate measurements impossible.
Furthermore, as the temperature of the liquid evaporated in the container decreases, dew condenses and wets the adsorbent, making accurate measurements impossible.

The adsorbent in the present invention is a substance or a combination of substances, such as paper, fiber, plastic, etc., which causes wicking by capillary action, and when a non-volatile liquid or a low-volatility liquid permeates into the adsorbent, There are no other restrictions as long as the display is transparent enough to allow the hidden display scale to be seen through.

The container in the present invention must be transparent, strong enough to hold and fix the adsorbent, non-volatile liquid or low-volatility liquid, and be made of a material that does not absorb or permeate the non-volatile liquid or low-volatile liquid. There are no restrictions.

The partition in the present invention is a material that does not adsorb or penetrate non-volatile liquids or low-volatility liquids, and there are no other limitations as long as it has the strength to block liquid.

Hereinafter, the present invention will be explained in more detail based on Examples, but the present invention is not limited to the following Examples.
In addition, the test method in Examples is as follows. Example 1 assumes a temperature time integration indicator for lunch boxes.

Adsorbent: Commercially available copy paper is used as the material.
Create two pieces approximately 85mm long, 2mm wide, and 70μm thick.
On one of the sheets, a display scale and color indicating the degree of safety are printed.
The scale is printed with 0.1mm lines every 1mm.
The printing material used is commercially available carbon toner for jet printers. The printed adsorbent is attached to another sheet of adsorbent with the printed side facing inside. (See [Figure 4])
This makes the surface look like a solid white piece of paper.

Non-volatile liquid: Uses cooking oil (olive oil).
Container for non-volatile liquids: Made of polypropylene. It is cylindrical with a length of about 35 mm, a thickness of about 0.1 mm, and an inner diameter of about 4 mm, with one side closed. (See [Figure 3] 2)
Absorbent cotton was stuffed into the cylinder to a length of about 25 mm to serve as a holder for the nonvolatile liquid. (See [Figure 3] 1)

Adsorbent container: Made of polypropylene.
It is cylindrical with a length of about 90 mm, a thickness of about 0.1 mm, and an inner diameter of about 4 mm, with one side closed. (See [Figure 3] 4)
The outer diameter of the adsorbent container is set to be slightly smaller than the inner diameter of the nonvolatile container.
The adsorbent container (see 4 in FIG. 1) is fixed by having its open end inserted into the open end of the non-volatile liquid container (see 2 in FIG. 3).

Partition: Made of polyethylene, approximately 50μm thick, approximately 5mm cylindrical with one side open. (See [Figure 3] 5)
The partition was sandwiched between a nonvolatile liquid container (see 2 in FIG. 3) and an adsorbent container (see 4 in FIG. 3).

The working mechanism of this example is that when the non-volatile liquid and adsorbent are separated by a partition, by removing the partition, the non-volatile liquid is adsorbed and transferred from the adsorbent and non-volatile liquid connecting part to the adsorbent. It begins with the start of. (See [Figure 5])
The migration rate of the non-volatile liquid of the adsorbent is according to the following test results: the higher the temperature, the faster the migration rate, showing a similar trend to bacterial growth.
The adsorbent suppresses light scattering on the surface of the paper in the area where the non-volatile liquid has been adsorbed, so the scale on the back side and the color indicating the degree of safety become visible on the front side.
This allows the degree of risk of bacterial growth to be displayed.

<Test results>
In Example 1, the partition was removed under temperature conditions of 20°C, 25°C, and 32°C, and the diffusion increase of the nonvolatile liquid to the adsorbent was started, and the diffusion distance was recorded every hour. Shown below. (Unit is mm)

As a safety indicator for boxed lunches, the Food Sanitation Law states that ``If the time from serving to eating is within 7 hours, there is a low possibility of food poisoning, and if it is within 4 hours, there is almost no possibility of food poisoning.'' ing.
Furthermore, an indicator that the number of viable bacteria in general is 1,000,000 cells/g or less is also shown. (Reference 1)
This means that when the indicator bacteria is Escherichia coli and assuming midsummer, if the initial number of bacteria is 10 cells/g, the number of bacteria after 7 hours at a temperature of 32° C. will be 1,000,000 cells/g or less.
At this time, the number of bacteria after 4 hours is 1,000 cells/g or less. (Reference 2)
The following table shows the time and diffusion distance when the number of bacteria becomes 1,000,000 cells/g or less, and the time and diffusion distance when the bacteria count becomes 1,000 cells/g or less at each temperature.

As shown in Table 2, the diffusion distance increases when the indicator bacteria grows to 1,000 cells/g at each temperature, and the diffusion distance increases when the indicator bacteria grows to 1,000,000 cells/g. The distances are almost the same.
Similar results can be obtained even if the indicator bacteria are replaced with food poisoning bacteria other than E. coli. (Reference 2)
This result shows that the diffusion distance of a non-volatile liquid or a low-volatility liquid can almost accurately represent the growth rate of microorganisms.

Reference 1

"Regarding Hygiene Standards for Lunch Boxes and Preparations" June 29, 1978 Kanshoku No. 161 Notification from the Director of the Food Sanitation Division, Environmental Sanitation Bureau, Ministry of Health and Welfare

Reference 2

Fujikawa, H. , Kai, A. , Morozumi,S. (2003): A new logistic model for bacterial growth. J. Food Hyg. Soc. Japan. 44, 155-160.

Cross-sectional view of a schematic diagram of the basic structure of the invention (before removing the partition) Cross-sectional view of a schematic diagram of the basic structure of the invention (after removing the partition) Exploded perspective view of a schematic diagram of the basic structure of the invention A perspective view of a schematic diagram of the adsorbent of the invention A perspective view of a schematic diagram of the basic structure of the invention

1 A non-volatile liquid or a low-volatility liquid 2 A container for enclosing a non-volatile liquid or a low-volatility liquid 3 An adsorbent with a display scale 4 A container 5 for enclosing an adsorbent with a display scale The connection part between 1 and 3 Removable or openable partition to shut off 3.1 Adsorbent Paper strip with printed scale 3.2 Adsorbent Strip of paper without scale printing

Claims (2)

By bringing a non-volatile or low-volatile liquid into contact with the adsorbent, it starts to diffuse into the adsorbent, and continuously indicates the degree of quality deterioration of food and drink due to microorganisms, etc. Temperature time integration indicator. In claim 1, the adsorbent has a feature that when the liquid passes through the adsorbent by a diffusion phenomenon, a display scale that is hidden in the adsorbent and cannot be seen is clearly displayed when the adsorbent is immersed in the liquid. Temperature time integration indicator.

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