JPH01178861A - Sensor for measuring freshness - Google Patents

Abstract

PURPOSE:To conduct the comprehensive evaluation of freshness of fish and flesh by measuring a sample directly, by a method wherein an oxygen-saturated buffer solution is supplied constantly to the fore end part of an oxygen electrode to which an immobilized microorganism is fitted and an introduction port is covered with a membrane which is permeable to a substance to be measured. CONSTITUTION:When an introduction port 4 is brought into contact with a sample, a substance to be measured is introduced from the sample 12 into the main body 3 of an apparatus through a membrane 5 and comes into contact with an immobilized microorganism fitted to the fore end part of an oxygen electrode 2 of a sensor 1 for measuring freshness. Accordingly, the respiratory activity of the germ is increased by low-molecular peptide, a free amino acid, sugar, etc. which are substances to be measured and exist in the sample, and as the result, the quantity of dissolved oxygen in a buffer solution in the main body 3 of the apparatus decreases. This change is detected by the oxygen electrode 2 and recorded as an electric response in a recorder 7.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a sensor for measuring freshness, and more particularly to a sensor for measuring freshness that utilizes the characteristics of microorganisms.

[Conventional technology]

The freshness of fish and livestock meat (beef, pork, etc.) is not only an important factor in determining its commercial value, but also an important factor from a hygiene perspective.

Many methods have been proposed for measuring the freshness, such as measuring the K value and measuring volatile base nitrogen.

[Problem that the invention seeks to solve]

However, most of the above measurement methods focus on individual substances that are hardly or not present in the salmon meat stage and are produced and increased over time due to autolysis and putrefaction. It is not possible to evaluate the freshness of
Moreover, the measurement required an extremely long time.

Therefore, in contrast to the conventional methods described above, the present inventors have developed and have already proposed a freshness measurement technology that uses microbial sensors to comprehensively evaluate the chemical changes occurring in the mountains. (Patent Application No. 1983-22931, Patent Application No. 62-2
78'lO1).

The above freshness measurement technology uses peptone, which is one of the nutritional sources for culturing microorganisms, as a low-molecular peptide derived from melted casein. We were surprised to find that this is the preferred source of nutrients, and we use a microbial sensor for freshness measurement, which is made by attaching immobilized microorganisms to the tip of an oxygen electrode.
The degree of increase in free amino acids, low-molecular peptides, sugars, etc. in the sample, that is, the degree of decrease in freshness, is measured as the amount of increase in the respiratory activity of microorganisms. In other words, low-molecular-weight peptides, free amino acids, sugars, etc. generated in the sample increase the respiratory activity of microorganisms and reduce the amount of dissolved oxygen in the sample. This change is detected with an oxygen electrode and constantly monitored. It is measured as an electrical response using the method.

According to the above technology, various chemical changes related to the freshness of fish or livestock meat can be comprehensively, quickly and simply measured, and the freshness can be determined.

However, in the above-mentioned one-time measurement technique developed by the present inventors, there is a problem in that a sample liquid containing the substance to be measured must be prepared in advance from the sample fish or livestock meat by a hot water extraction method or the like. was there.

Therefore, an object of the present invention is to provide a sensor for measuring freshness that can quickly and easily perform a comprehensive freshness evaluation of fish and livestock meat, and without having to prepare 4 sample liquids in advance. There is a particular thing.

[Means for solving problems]

As a result of various studies, the present inventors installed an inlet shielded by a specific membrane in a freshness measurement sensor equipped with a device body that has a built-in oxygen electrode with immobilized microorganisms attached to the tip. It has been found that by bringing the inlet into contact with a sample such as fish meat under predetermined conditions, the freshness of the sample can be directly measured and the above objective can be achieved.

The present invention has been made based on the above findings, and provides the following inventions.

The device has a built-in oxygen electrode with immobilized microorganisms attached to the tip, and the tip of the oxygen electrode has an oxygen-saturated state of 4
The device is configured such that Ji liquid can be supplied at all times, and the device main body is provided with an introduction port for bringing the substance to be measured into contact with the sample to be measured, and the inlet port is configured to allow the substance to be measured to permeate through the sample. A freshness measuring sensor (integrated structure) that is specially shielded by a transparent membrane.

The device body is equipped with an oxygen electrode with immobilized microorganisms attached to the tip thereof, and the tip of the oxygen electrode is provided with an oxygen saturated buffer so that it can be constantly supplied with the buffer. A contact section connected via a liquid is provided in series, and the contact section is provided with an inlet for bringing the substance to be measured from the sample into contact with the sample, and the inlet is configured as described above. A sensor for measuring freshness (separate structure) characterized by being shielded by a membrane that allows the substance to be measured to pass through.

[Effect]

In the freshness measurement sensor configured as described above, the substance to be measured can be taken into the main body of the apparatus from the sample gage 4 through the inlet, so that the freshness of the sample can be directly measured.
1! 'l can. Further, by providing the introduction port in a contact portion separate from the main body of the device, the direct measurement can be performed more easily and conveniently.

〔Example〕

Next, a first embodiment of the freshness measurement sensor of the present invention will be described.
This will be explained based on the diagram.

FIG. 1 is a half-sectional view schematically showing an embodiment of the sensor for measuring freshness of the present invention, and FIG. 2 is a schematic half-sectional view showing an oxygen electrode with immobilized microorganisms attached to the tip, which constitutes the sensor. It is a diagram.

The freshness measuring sensor 1 shown in FIG.
and a discharge port 3b are formed so that an oxygen saturated buffer solution can be constantly supplied to the tip of the oxygen electrode 2.

The apparatus main body 3 is provided with an inlet 4 for bringing the substance to be measured from the sample into the apparatus main body 3 by bringing it into contact with a measurement sample (not shown in FIG. 1). , the inlet 4 is connected to a membrane 5 through which the substance to be measured is permeable.
is shielded by.

This membrane 5 is attached around the lower part of the device main body 3 with an O-ring 6 in the figure.

The membrane 5 can be used without any particular restriction as long as it is a membrane through which the substance to be measured can permeate, but specific examples include dialysis membranes, membrane filters, and ultrafiltration membranes.

Furthermore, there are no particular restrictions on the method for attaching the immobilized microorganisms to the tip (electrode portion) of the oxygen electrode 2, but as shown in FIG. 22 in sequence, and then the dialysis membrane 2
An example can be given of covering 3. Note that the Teflon membrane 21 and the dialysis membrane 23 each have an O ring 24.
and 25 are fixed around the oxygen electrode 2.

Further, the oxygen'@ electrode 2 is inserted from above the device main body 3, and the mounting member 31 is screwed onto the upper part of the main body 3.
is fixed.

Next, the operation of the freshness measuring sensor of this embodiment will be explained with reference to FIG. 3 as well.

FIG. 3 is a schematic diagram of an example of a measurement system including the freshness measuring sensor 1 of this embodiment. The measurement system shown in the figure is basically immersed in a constant temperature water bath 7 and maintained at a constant temperature. an oxygen-saturated buffer 8, a pump 9 for supplying the buffer 8 to the freshness measurement sensor 1, a pump 9as for discharging the buffer 8 from the freshness measurement sensor 1 to the outside of the measurement system; It is comprised of a recorder IO for recording the electrical response of the freshness measuring sensor 1. Outside of this,
In the figure, reference numeral 11 denotes an air introduction tube, which blows air into the buffer solution 8 to bring the amount of dissolved oxygen in the buffer solution 8 into a saturated state in order to obtain a stable electrical response.

First, the buffer solution 8, which is stable under predetermined conditions, is
It is supplied to the freshness measurement sensor 1 at a predetermined flow rate to define a reference state for measurement. This appears on the recorder 10 as a stable baseline.

Next, as shown in the figure, the membrane 5 of the freshness measuring sensor 1 is
The inlet 4, which is shielded by the inlet, is brought into contact with the sample 12, and this state is maintained for a predetermined period of time, and the electrical response at that time is recorded on the recorder 10.

The freshness measured by the freshness measurement sensor 1 of this embodiment is determined and evaluated based on the peak height or peak area recorded on the recorder 10.

That is, by bringing the inlet 4 into contact with the sample as described above, the substance to be measured is introduced from the sample 12 into the main body 3 of the apparatus through the membrane 5, and the substance to be measured is introduced into the main body 3 of the apparatus from the sample 12 through the membrane 5. and is configured to contact immobilized microorganisms attached to the microorganism. Therefore, the respiratory activity of the iM organism increases due to the substances to be measured, such as low-molecular peptides, free amino acids, sugars, etc. present in the sample, and the amount of dissolved oxygen in the buffer solution in the fruiting device main body 3 decreases. This will be it. This change can be detected by the oxygen electrode 2 and recorded on the recorder 7 as an electrical response.

In addition, the response of the freshness measurement sensor 1 in the measurement system shown in Figure 3 shows that the lower the freshness of the sample, the more low-molecular-weight peptides, 'f1-released amino acids, sugars, etc. increase due to autolysis or the action of microorganisms. So it gets bigger. Therefore, as described above, the freshness of a sample can be judged by the peak height or peak area recorded on the recorder 10, and the worse the freshness is, the larger the peak height or peak area becomes.

As explained above, according to the freshness measuring sensor 1 of this embodiment, the comprehensive freshness evaluation of the sample 12 can be performed quickly and easily, and without any pre-treatment of the sample 12 (destroying the sample). Kotona () can be measured directly.

Next, the freshness measuring sensor of the present invention will be described in more detail.

The microorganisms used in the microbial sensor for measuring freshness of livestock meat of the present invention can be used without any particular restriction as long as they utilize substances that are produced and increased as freshness decreases. Examples include the putrefactive bacteria shown in . In general, aerobic microorganisms that are harmless from a food hygiene perspective and whose respiratory activity correlates with the freshness index can be preferably used. In addition, when immobilizing microorganisms and attaching the immobilized microorganisms to the tip of an oxygen electrode, it is preferable to cover the tip with a dialysis membrane or the like.

[Table-1] Achr bacteria that can be used for microbial sensors
omobacter butyri
・Achromobacter lipolyticum
(Achromobacter livoliiticum) 8lcali
genes (Alcaligenes) Alcali (Heres viscosus (Alcaligenes viscosus) Alteromonas putrefaciens (
Alteromonas piutrifaciens) Bacil
lus alvei Bacillus cereus Bacillus circulans Bacillus firmus 13aC4llHlicheniformis Bacillus macerans (Bacillus stearothermophilis) ) Bacillus
s 5ubtilis (Bacillus subtilis) Enterobacter aerobenes (Enchabacter aerohenames) Enterobacter cloacae (Enchabacter cloacae) Flavobacterium (Flavobacterium) Lactobacillus Lactobacillus casei Lactobacillus fermentum LacLobacillus heterohioch
Lactobacillus hiochii Lactobacillus hiochii Lactobacillus flus Leuconos toc Micrococcus auranticus ) Gate 1crococcu
s candidus (Microconcus candidus) Micrococcus flavus (Micrococcus flavus) Micrococcus freudenreichi
i (Micrococcus frudenleichii) Micr
ococcus ureae Micrococcus varians Mixococcus ProLeus m1rabiris Pseudomonas fluorescens ( Pseudomonas fluorescens) (Pseudomonas fluorescens)
Pseudomonas (Pseudomonas) Serratia marcescens (Serratia marcescens)
Marcesoscens) Serratia (Streptococcus thermophilus) Vibri.

(Vibrio) In addition, in order to immobilize the above-mentioned microorganisms and attach the immobilized microorganisms to the tip of the oxygen electrode, for example, the culture solution in which the microorganisms are cultured is filtered with a membrane filter. This can be done by adsorbing and immobilizing microorganisms on the oxygen electrode, cutting out the filter on which the microorganisms have been adsorbed and immobilized to an appropriate size as necessary, and attaching the filter to the tip of the oxygen electrode.

Further, the oxygen electrode used in the freshness measurement sensor of the present invention is not particularly limited, and various types can be used.

Further, as the freshness measuring sensor of the present invention, the first
For example, as shown in FIG. 4, the device body 3 is provided with a configuration substantially similar to that of the above embodiment, but the device body 3 is not limited to what is shown in the figure. The opening 4 may not be provided, but may be provided in the contact portion 14 which is connected to the main body 3. The contact portion I4 and the main body 3 are connected by a pipe 13 for supplying a buffer solution into the main body 3, and are connected to each other via the buffer solution. Therefore, when applying the freshness measurement sensor 1 of the embodiment shown in FIG. 4 to the measurement system of FIG. 14, and then the buffer solution 8 is supplied into the device body 3 via the outlet 14b, the pipe 13 and the supply port 3a of the device body, and is then discharged from the outlet 3b. Incorporate into measurement system. The measurement is carried out in the same manner as in the previous embodiment by bringing the inlet 4 of the contact section 14 into direct contact with the sample 12.

In the case of the embodiment shown in FIG. 4, the inlet 4 for contacting the sample and taking in the substance to be measured from the sample is provided in the contact part 14, which is separate from the main body 3 of the apparatus. , measurement of the sample 12 can be performed more easily and conveniently.

Next, the sensor for measuring freshness of the present invention will be specifically explained by giving an experimental example in which the sensor is used to measure freshness.

Experimental example Samples of commercially available tuna fillet and beef cubes with different freshness were prepared by changing storage conditions such as temperature and time, and the measurement system shown in Figure 3 was used to measure each sample. At the same time as measuring the freshness, a sensory test was conducted on the sample.

Figure 5 shows the relationship between the two when the horizontal axis is the peak height recorded on the recorder lO and the vertical axis is the degree of deterioration of freshness (the larger the number on the scale, the lower the freshness). This is the graph shown in .

The sensory test was conducted by grilling each sample like a steak and actually eating it. As a result, it was found that there is a close relationship between freshness and taste as determined by sensory tests, with the lower the freshness, the lower the taste. The area above scale 3 on the vertical axis was rotten and could not be eaten.

As is clear from FIG. 5, biosensor 1 of the present invention
There was a close relationship between the peak height recorded during measurement and the freshness of tuna meat (fish meat) and beef (livestock meat), and a correlation was also observed between the taste.

In addition, in the above measurement, Simon
Alteromonas buterifaciens cultured in S'medium at pH 7.2 and temperature of 25°C was used.

The immobilized microorganism film was prepared by using a membrane filter to adsorb and immobilize 1 ml of the culture solution containing the above-mentioned indicator bacteria, and then cutting out the obtained feeder into a circular shape with a diameter of 3I. was used.

Furthermore, the conditions of the measurement system were as follows.

Loose j! i-solution diphosphate buffer (0, L M> pH 7, 0 temperature
28℃ Flow rate 0.6 ml/min
.

Number of bacteria on the immobilized microorganism film: 5XLO' pieces/cd In addition, in this experimental example, a membrane filter with a pore diameter of 2 μm was used as a membrane for shielding the inlet provided in the sensor for measuring freshness.

〔Effect of the invention〕

The freshness measuring sensor of the present invention has the effect that comprehensive freshness evaluation of fish meat and livestock meat can be performed quickly and easily by directly measuring a sample.

[Brief explanation of the drawing]

Figure 1 is a half-sectional view schematically showing an embodiment of the sensor for measuring freshness of the present invention, Figure 2 is a schematic diagram showing an oxygen electrode with immobilized microorganisms attached to the tip, and Figure 3 is a diagram for measuring freshness. FIG. 4 is a half-sectional view showing an outline of the freshness measuring sensor of another embodiment, and FIG. 5 shows the freshness of the sample and the output value of the freshness measuring sensor. It is a graph showing the correlation. 1... Sensor for freshness measurement 2... Oxygen electrode 4... Inlet port, 5... Roku 12... Sample 22... Immobilized microorganism patent applicant Taiyo Fishery Co., Ltd. Figure 1 Figure 2 Figure 3

Claims (2)

[Claims] (1) The device body includes an oxygen electrode with immobilized microorganisms attached to the tip thereof, and is configured such that an oxygen saturated buffer solution can be constantly supplied to the tip of the oxygen electrode, and the device body includes: A sensor for measuring freshness, characterized in that an inlet is provided for bringing in a substance to be measured from the sample by bringing it into contact with the sample, and the inlet is shielded by a membrane through which the substance to be measured is permeable. (2) The apparatus body is equipped with an oxygen electrode having a built-in immobilized microorganism at its tip, and is configured such that an oxygen saturated buffer solution can be constantly supplied to the tip of the oxygen electrode, and the apparatus body has the above-mentioned A contact part connected via a buffer solution is provided in series, and the contact part is provided with an inlet for bringing into contact with the measurement sample and taking in the substance to be measured from the sample,
A sensor for measuring freshness, characterized in that the inlet port is shielded by a membrane through which the substance to be measured can pass.