JPS59217145A - Total sugar amount measuring apparatus - Google Patents

Abstract

PURPOSE:To measure the total sugar continuously and quickly by mixing a strong electrolytic solution being fed from a reagent pipeline with a sample liquid or a washing liquid alternately fed from a sample pipeline or a washing pipeline, thereby measuring and calculating the conductivity of measuring liquid. CONSTITUTION:A strong electrolytic aqueous solution of NaCl or the like being supplied from a reagent storage tank is fed to a pump 8 through a filter 9. The solution from the pump 8 flows through a reagent pipeline 1 through a damper 10 and fed to a mixer 5 via a mixing point (MP)11. A washing liquid comprisng pure water and the like is fed to a washing pipeline 3 thrugh a filter 9, the pump 8 and the damper 10 and further, a sample liquid such as food sample is fed to a sample pipeline 2 from a sample source through a pump 13 and a filter 14. The sample liquid and the washing liquid are switched alternately with a switching valve 4 and forced to an MP11. The measuring liquid mixed with a mixer 5 is measured on the conductivity with a flow through type 4 electrode cell 6 and the total sugar amount is computed from a conductivity signal with an arithmetic processing circuit 7 to be displayed.

Description

Detailed Description of the Invention This invention provides a total sugar content measurement method that allows the total sugar content (total amount of monosaccharides and disaccharides) contained in food to be determined continuously, easily, quickly, and accurately by conductive dust measurement. It is related to the device.

There are various factors that determine the quality of food.
Among these, sweetness is an important factor that controls food quality.

However, there is a method for measuring the total sugar content (hereinafter referred to as sugar content) of monosaccharides (glucose, fructose, galactose, etc.) and disaccharides (sucrose, lactose, maltose, etc.) that are the main components of sweetness contained in foods. As of now, chemical methods (phenol-sulfuric acid method and orcinol-sulfuric acid method)
There are no other reliable methods or equipment, and this has become a major bottleneck not only in terms of food production and manufacturing, but also in terms of research. For example, the optical rotation method (optical rotation needle) used in the sugar industry
is essentially unusable in natural products such as fruits, since various sugars and organic substances with different degrees of optical rotation coexist.

In addition, the refractive index measurement method (refractometer), which is currently the only on-site analysis method that is widely used, has an error rate of 13% because it measures the amount proportional to the total soluble solid content rather than the sugar content.
exceed. On the other hand, the above-mentioned chemical methods not only require skill, but also are complicated and time-consuming to operate, so they are basically not suitable for on-site analysis. From these current circumstances,
The development of methods and devices that can accurately, simply, and quickly measure sugar content has been an urgent requirement for the food industry.

In order to meet such demands, the present inventors have previously developed a completely new viscous NMI) method based on an electrochemical method, that is, an electrical conductivity measuring method.

The measurement method proposed by the present inventor is to measure the actual conductivity of various coexisting substances such as organic acids and inorganic components by adding a certain amount of strong electrolyte (potassium chloride or sodium chloride) to a food sample, that is, a multi-component mixed system. control the impact on the rate,
At the same time, the aim is to measure the amount of sugar z as a specific amount proportional to the change in rate, as shown in the following equation.

Kc = cl, AO eneee... (1) A
o tpIρ ψ ψρ where C is the sugar concentration in the food sample) and I (Q is the conductivity of the sugar-electrolyte solution. Also, A, Q %ψ,
1 is the effective cross-sectional area, resistivity, and length when the sugar-electrolyte solution is regarded as a conductor, and ρ is the sugar density.

That is, the final method is the conductivity when non-conductive spheres (sugar) of density ρ are uniformly dispersed in a concentrated (06~I D, J) strong electrolyte solution as a medium-conductor at a concentration C? 1
! The measured electrical conductivity does not depend on the type of sugar, but only on the sugar concentration (weight %). In other words, this is the ideal time for measuring total sugar content.

However, the measurement of electrochemical properties of electrolyte solutions, that is, standard two-way treatment, is difficult for dilute solutions (<10"M
) & This is possible only for 0, 6 to I used in the final method.
The example in which a concentrated solution such as M (actually measured conductivity: 6 to 118 m-') was handled is quite η poor. In other words, it is impossible to accurately measure sugar content using the powder method, that is, to put the powder method into practical use with existing measuring devices.

On the other hand, the development of modern industry demands labor-saving, speedy, and accurate process control and measurement, and the continuous and automation of the analysis process is essential for the generalization of this measurement method.

This invention was made in consideration of the above circumstances, and it is possible to continuously process and measure a large number of food sample liquids such as fruit juice easily, quickly, and accurately, and to determine the sugar content regardless of the skill level of the technician. It is an object of the present invention to provide a total sugar amount measuring device that can accurately determine the amount of sugar.

The total sugar content measuring device of the present invention will be explained below with reference to the drawings.

Figures 1 and 2 show a practical example of the total sugar content measuring device of the present invention. The total sugar content measuring device shown in this example consists of a reagent conduit 1 for delivering a strong electrolyte solution, a sample conduit 2 for delivering a sample solution, a cleaning pipe 3 for delivering a washing solution, and a sample pipe for the above-mentioned sample. A switching valve 4 that switches between the pipe line 2 and the cleaning pipe line 3 to alternately flow the sample liquid and the cleaning liquid; a mixer 5 that uniformly warms the combined strong electrolyte solution and sample liquid or the strong electrolyte solution and the cleaning liquid; A flow-through type four-electrode cell 6 (hereinafter abbreviated as flow cell) is used to flow the measurement liquid mixed in the mixer 5 and measure the conductivity of the measurement liquid, and the sugar content is calculated from the conductivity signal from this flow cell 6. A multi-channel microtube pump (hereinafter abbreviated as pump) 8 is used to pump the solution through the reagent conduit 1 and the cleaning conduit 3, and a switching valve is used. 4 uses a hexagonal valve.

A highly concentrated aqueous electrolyte solution such as sodium chloride (NaC61) and potassium chloride (Kcal) sent from a reagent storage tank (not shown) is first passed through a filter 9 in which the tube body is filled with glass wool or the like in the reagent conduit 1. After the foreign matter is removed, it is sent to the pump 8.

The pump 8 is a microtube pump having 5 channels, one channel is allocated to the reagent conduit 1, and the remaining 4 channels are allocated to cleaning conduits as will be described later. The strong electrolyte solution and the cleaning liquid flowing through the cleaning liquid pipe line 3 are pumped at a flow rate ratio of 1:4.

The strong electrolyte solution leaving pump 8 is sent to damper 10. This dan
As shown in FIG. 3, there are two damper bodies 10a each made of a hollow cylindrical body, and a resistance tube 10b made of a small diameter tube.
The strong electrolyte solution that has passed through this damper 10 is sent to a mixer 5 via a mixing point (hereinafter abbreviated as MP) 11.

Further, a cleaning liquid made of pure water or the like is supplied to the cleaning pipe line 3 from a cleaning liquid tank (not shown). The cleaning liquid supplied to this cleaning pipe line 3 is filtered through a filter 9 similar to the reagent pipe line 1.
After foreign matter is removed by four branch lines 12...
・Sent to. This branch line 12 is composed of a tube having the same diameter as the reagent pipe line 1, and each branch line 1
The cleaning liquid flowing through the dampers 1 and 2 is pumped by the pump 8 at the same flow rate as the strong electrolyte solution flowing through the reagent pipes 1, respectively.
Forced to 0. The cleaning liquid that has passed through the damper 10 is combined again and sent to the switching valve 4 at a flow rate four times that of the electrolyte solution.

Further, from a sample source (not shown), a sample conduit 2
A sample solution of a food sample, for example fruit juice, flows into the container.

A pump 13 is provided in the sample conduit 2 , and the sample liquid flowing therein is sent to a filter 14 . This filter 14 serves as an air trap that removes insoluble solids from the sample liquid and prevents air bubbles from flowing into the pipe.
The sample liquid that has passed through is sent to valve 4 through I and Il.

The switching valve 4 is made of a hexagonal valve, and this switching valve 4 includes:
In addition to the sample pipe line 2 and the washing pipe line 3, there is also a switching valve 4.
A connecting pipe 15 that sends the sample liquid or washing liquid that has been pressure-fed to the MPII, a discharge pipe 16 that discharges these, and both ends of a sample injection pipe 17 having a predetermined volume for measuring the sample solution are connected. ing.

By switching this switching valve 4, the sample liquid and washing liquid that have been pressure-fed to this switching valve 4 can be alternately transferred to MPII.
Pressure is sent to First, when the switching valve 4 is switched to the state shown by the solid line in FIG. 1, the cleaning liquid is sent from the cleaning pipe line 3 to T', 4 P 11 via the connecting pipe 15. Further, the sample liquid sent from the sample pipe line 2 is discharged from the discharge pipe 16 via the sample injection pipe 17. Next, when the switching valve 4 is switched to the state shown by the dotted line in FIG.
The sample liquid present in the sample injection tube 17 is pushed out by the cleaning liquid sent from the cleaning pipe line 3 and sent to MPll.

In MPII, the strong electrolyte solution sent from the reagent conduit 1 and the sample liquid or washing liquid sent via the switching valve 4 are combined and sent to the mixer 5. On this occasion,
A predetermined amount of the sample solution that merges with the strong electrolyte solution in the sample injection tube 17 is pumped 1° from the cleaning conduit 3 to the pump 8.
It is pushed out by the cleaning liquid that is sent at a flow rate four times that of the strong electrolyte solution. Therefore, the sample liquid and the strong electrolyte solution are mixed in predetermined amounts at a predetermined ratio, and the measurement liquid produced by them is a solution containing the strong electrolyte at a predetermined concentration.

The strong electrolyte solution and the sample solution or the strong electrolyte solution and the cleaning solution that have been combined in this MPII are mixed uniformly in the mixer 5, and the mixed solution is used to separate the measurement solution or the previous and subsequent measurement solutions and to clean the 74-cell 6. becomes. This mixer 5 is made up of a thin tube wound into a coil, and the measurement liquid and mixed liquid that have passed through this mixer 5 are sent to a flow cell 6.

The flow cell 6 is for measuring the electrical conductivity of the measuring liquid, and as shown in FIG. 4, its main body 6a is formed of polyacetal resin or the like into a substantially hollow columnar shape. The hollow space (5i%) of this flow cell 6 is a probe chamber 6b through which the measurement liquid and the mixed liquid flow.

This probe chamber 6b includes a pair of current-carrying electrodes 6c, 6c arranged at both ends of the probe chamber 6b, and a pair of current-carrying electrodes 6c, 6c arranged at both ends of the probe chamber 6b.
a pair of probe electrodes 6 d, disposed between 6 c and 6 c;
6a are provided, and these electrodes 6c, 6c
- Platinum is preferably used for 6as6a.

The conductivity of the measurement liquid sent from the mixer 5 to the probe chamber 6b of this flow cell 6 is measured by the current-carrying electrodes 6c, 6c and the probe electrodes 6a, 6a, and the mixed liquid is sent to the probe chamber 6b and each group si6. Q, 6 o・
After washing 6d and 6d, the temperature of the liquid is measured by the temperature sensor 18 and sent to the filter 19.

This filter 19 is for removing solid matter that may be generated due to salting out when a highly concentrated strong electrolyte solution and a sample liquid are mixed. The measurement liquid and mixed liquid passed through the filter 19 are sent to the resistance tube 20.

This resistance tube 20 is made of cedar bark and is made of a thin tube with a diameter of about 100 mm, and is used to increase the resistance when the measurement liquid or mixed liquid flows, and to increase the liquid pressure in the probe chamber 6b of the flow cell 6. . The measurement liquid and mixed liquid that have exited the resistance tube 20 are discharged from the discharge port 21.

Next, the arithmetic processing circuit 7 connected to the current-carrying electrode 6a, 6as probe electrodes 6a, 6a, and temperature sensor -18 of the flow cell 6 will be explained.

As shown in FIG. 2, first, a standard resistor 22 is provided in series with the current-carrying electrode 6as6a, and these are set to a predetermined value by a sine wave AC oscillator 23 and a constant current circuit 24, regardless of the liquid resistance of the measuring liquid. A predetermined current is applied at a frequency.

Next, a differential amplifier 25 is connected to the probe electrode 6d%6d. This differential amplifier 25 sends the potential difference between the probe electrodes 6d and fz1, which is proportional (inversely proportional) to the liquid resistance (conductivity) of the solution flowing in the probe chamber 6b, to the differential amplifier 26 as a conductivity signal. A differential amplifier 27 is also connected to the standard resistor 22, and a signal of a predetermined voltage is sent from the differential amplifier 27 to the differential amplifier 26.The standard resistor 22 is connected to the probe electrode 6a.

The conductivity signal sent from 6d to the differential amplifier 26 via the differential amplifier 25 is a high blank, and the change due to the conductivity of the measurement liquid is relatively small. It is something that was given. In the differential amplifier 26, the signals sent from the differential amplifier 25 and the differential amplifier 27 are subtracted, and a conductivity signal subjected to zero subregion is sent to the voltage detector 28. The conductivity signal sent to the voltage detector 28 is converted from alternating current to direct current, and then sent to the central processing unit 29 after its voltage level is converted.

This central processing unit @29 includes the temperature sensor 18.
Temperature information of the measuring liquid sent from the temperature correction circuit 3o connected to the temperature correction circuit 3o and a conductivity signal sent from the voltage detector 28 are input. In the central processing unit 29, these information signals are processed using a relational expression of sugar concentration-measuring liquid conductivity-measuring liquid temperature, etc., which have been input in advance, and the sugar content of the sample liquid is determined. This sugar content signal is sent to the digital voltmeter 31, and the sugar content in the sample liquid is displayed and recorded.

In the life sugar amount measuring device configured in this way, the cleaning liquid and the sample liquid are alternately sent by switching the switching valve 4, and are combined with the strong electrolyte solution at the mixing point (MP) 11.
The mixer 5 uniformly mixes the mixed liquid and the measuring liquid, each having a cleaning effect, and sends them to the cell 6, where the electrical conductivity is measured. Based on this electrical conductivity, the arithmetic processing circuit 7 determines the sample liquid. Since the sugar content of the sample is calculated and displayed, the apparatus can easily and quickly process a large number of sample liquids such as fruit juice in succession, and can accurately determine the sugar content.

In addition, the mixing ratio of the strong electrolyte solution and the sample liquid for making the measurement liquid is determined by the ratio of the flow rate of the cleaning liquid that pushes the sample liquid to the MPII and the flow rate of the sample flow. It is determined by the distribution ratio of the channels to the cleaning line 3 and the reagent line 1 in the tube pump (pump) 8. Therefore, even if the amount of liquid sent by the pump 8 changes, the strong electrolyte solution and the sample liquid are mixed at a stable mixing ratio and become the measurement liquid, so the concentration of the strong electrolyte in the measurement liquid is kept stable. Accurate sugar content can be measured.

Furthermore, the flow cell 6 includes current-carrying electrodes 6 c , 6
c and probe electrodes 6a, 6a are provided, and the functions are separated as electrodes for conducting current and electrodes for measurement, so this flow cell 6 has a low electrode interface impedance even when the measurement liquid exhibits high conductivity (6 to 118 m-'). It becomes possible to accurately measure the conductivity without being influenced by the sugar content, and therefore the sugar content can be determined more accurately. Furthermore, if these T4T, poles 6C, 6C, 6ti, and 6d are made of platinum, it is possible to measure sample liquids such as fruit juice containing a large amount of colloidal polymer substances more stably and accurately than in 1.

Next, the total sugar content measuring device of the present invention will be explained in more detail by showing experimental examples.

[Experimental Example 11 Equipment Operation and Calibration Curve] Several types of sucrose solutions with known concentrations were prepared and used as sample solutions. A 4.5 M NaCe solution (room temperature saturated solution) is used as a strong electrolyte solution, and a nonionic surfactant that has little effect on conductivity is added to deionized water with a conductivity of 1 × 1 o-'S-m-' order. Tri) i-100 (product name) to 0.1
% was added as a cleaning solution. These solutions were sent to the apparatus shown in the above example, the brightness was determined, a calibration curve of conductivity-sucrose concentration was created, and its linearity was examined. On this occasion,
The measurement was carried out at 20°C, the flow rate ratio of the cleaning solution and the strong electrolyte solution was 4:1, and the Na and Ce concentrations of the measurement solution were 0.9M.
It was said that

In addition, an outline of the specifications of each component of the total sugar content measuring device is shown below.

For the reagent conduit 1, a Teflon tube with an inner diameter of 1.5 mm was used. The same tube was used for the branch line 12, and this line 12 was made of four pieces of wood. For Genbu 8, a multi-channel microtube pump MP-1001 type (trade name: Tokyo Rikaki Makoto) was used. According to this, reagent conduit 1,
The amount of liquid sent through the branch line 12 is 0 per channel.
．． The distance was 46 m and 17 minutes.

The main body 10a of the damper 10 has an inner diameter of 0.9α and a length of 3.
Resistance tube 1 using crrL polycarbonate pipe
A Teflon tube with an inner diameter of 0.25 mm and a length of 50 cm was used. A Teflon tube with an inner diameter of 2 mm is used for the sample injection tube 17, and the mixing point (MP
) 1 unit volume of sample liquid sent to 11 is 0.68
The length was set so that it was ml.

For the mixer 5, a stainless steel tube with an inner diameter of 08 m1I+1 and a length of 80 cm was wound into a coil with an inner diameter of 10 mm. The probe chamber 6b of the flow cell 6 has a length of 5 cIn, with a diameter of 51 Trms at both ends and a diameter of 1 Trms at its center.
There were 5 questions. Current-carrying electrodes 6o and 6a were provided at a distance of 5cIrL at both ends of the probe chamber 6b with a diameter of 3mm, and their protrusion dimension was 3mm. These current-carrying electrodes 5c and 6c have a diameter of 1
A platinum wire was used for the connection. Also, the central diameter of the probe chamber 6b is 1
．． In the part 5, probe electrodes 6 a, 6 at-
They were provided at intervals of 2 cIn, and their protruding dimensions were a little less than os mm. This probe electrode 6d.

A platinum wire with a diameter of 0.5 wire was used for 6d. The cell constant θ of this Freisel 6 is θ=1.114X10 regardless of the flow rate.
~1 was 0 energized electrode of this flow cell 6 60% 6Q
Connect a standard resistor 22 of Ω to 1.5, and set the frequency to 1 kn.
At e, a current of 25α0 μA was passed regardless of the liquid resistance, and the conductivity of the measurement liquid was measured by a constant current method.

As a result of the measurement in this manner, the conductivity signal 32 shown in FIG. 5 was obtained from the differential amplifier 26. The sample peak 33 of this signal 32 indicates the liquid resistance of the measurement liquid, and this value is processed using the cell constant θ of the flow cell 6 to determine the conductivity, and the results are plotted for each concentration of sucrose solution, as shown in Figure 6. The calibration curve shown in was obtained.

It can be seen from this calibration curve that a good linear relationship is established between the concentration of the sucrose solution and the conductivity of the measurement liquid in this device (correlation coefficient γ=-0,999).

[Experimental Example 2, Continuous Operation of the Apparatus] The apparatus shown in Experimental Example 1 was operated under the same conditions as Experimental Example 1, during which a 20 W/W% sucrose solution was injected as a sample liquid at predetermined intervals. . The sucrose concentration was determined from the conductivity of the measured solution using the calibration curve shown in FIG. 6, and the value 1 hour after the start of operation was set as 100 and relative display was obtained, and the results shown in FIG. 7 were obtained. This result shows that the measurement error caused by continuous operation of this device for 12 hours is 3.8% at maximum.

However, this ratio is sufficiently small compared to the permissible measurement error of ±5% in chemical analysis and @mechanical analysis, and since the error increases at an almost constant rate with operating time, it is possible to Correction is possible, and if this correction is performed, continuous measurement over a long period of time can be performed with higher accuracy.

EXAMPLE Using the total sugar content measuring device shown in Experimental Example 1, the reproducibility of measurement and the time required for analysis were investigated under the same conditions.

When a 10 w/w% sucrose solution was continuously injected 10 times as a sample solution, an error of only ±0.05 w/w% occurred. Further, the time required from injecting the sample to obtaining a response was a little less than 1 minute.

EXAMPLE The sugar content in citrus juice, apple juice and sugar beet root juice was measured using the same conditions and equipment as shown in Experimental Example 1 and compared with the sugar content determined by the phenol-sulfuric acid method.

First, prior to the measurement of citrus juice, a relational expression of sugar content-conductivity-liquid temperature was determined using a model sample liquid, and this was input into the central processing unit 29.

As a model sample solution, a solution was used in which sucrose, glucose, and fructose were mixed as sugars at a weight ratio of 7:2 to 10, and a predetermined amount of citric acid and potassium citrate was added. Table 1 shows the results obtained for Citrus fruit juice such as Satsuma mandarin juice, Hatsusaku fruit juice, and commercially available fruit juice-containing drinks.

Table 2 also shows apples (Fuji, Tamakai,
Table 3 shows the results of measuring the sugar content in the juice of betel leaf root.

Table 1 Citrus juice and juice-containing beverages Table 2
As can be seen from apple juice Tables 1 to 3, a good correspondence was obtained between the two, and it was demonstrated that the apparatus of the present invention can determine the sugar content with an accuracy comparable to that of the phenol-sulfuric acid method.

In the above description, a common pump 8 was used to transport the solution in the reagent pipe line 1 and the cleaning pipe line 3, but different pumps may be used. In addition, each pipe line 1.2.3 is not limited to a pump 8.13 for transporting the solution, but it is also possible to transport the solution by using the difference in height from the storage tank (not shown) of each solution, or by using high-pressure gas. You may also use a method such as sending the solution using a liquid flow rate, and in this case, a flow rate adjustment valve or the like can be used to adjust the flow rate of the solution.

Furthermore, although a case has been described in which a 60,000 valve is used as the switching valve 4, a solenoid valve or the like may be used as the switching valve 4.

However, if a pump is used to transport the solution in this case,
The pump and solenoid valve provided in the sample pipe line 2 and the washing pipe line 3 need to be operated in conjunction with each other.

Further, the strong electrolyte solution in the reagent conduit 1 and the sample liquid in the sample conduit 2 were mixed at a ratio of 1:4, but since the measurement conditions change depending on the type of sample, this ratio can of course be changed.

When this ratio is changed, in the example apparatus shown in FIG. 1, the ratio of the number of reagent conduits 1 to the number of branch lines 12 is changed.

Furthermore, in the example apparatus shown in FIG. 1, noise is generated in the conductivity signal measured by the flow cell 6 as the switching valve 4 is switched. A bypass consisting of a thin tube provided with a valve that opens in conjunction with switching of the switching valve 4 may be provided between the end portion and the connecting pipe 15.

Furthermore, the present inventor has found that the previously developed method for measuring the total amount of sugar in food can be applied to substance G, which behaves as a resistor in the same way as sugar in a concentrated sleep solute solution. The method has been developed as a measurement method in which the concentration of the substance to be measured is determined from the electrical conductivity of a measurement solution containing a strong electrolyte. Good results have been obtained as a method for determining moss content, fat content, and moss total solid content. Therefore, it is expected that the scope of use of the measuring device of the present invention will expand in the future.

As explained above, the total sugar content measuring device of the present invention uses a strong electrolyte solution sent from the reagent pipe and a sample sent alternately from the sample pipe or cleaning pipe by switching the switching valve. The solution or cleaning solution is mixed uniformly with a mixer to form a mixed solution with a cleaning action and the measurement solution is flowed through the probe chamber of the flow cell.The 70-cell measures the bulk conductivity of the measurement solution, and the conductivity signal is obtained. is processed by an arithmetic circuit to determine the sugar content, etc.

Therefore, the measuring device of the present invention is a device that can easily, quickly, and accurately process and measure a large number of sample solutions obtained from various foods and their raw materials, and accurately determine their sugar content. Become.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing an example of the total sugar content measuring device of the present invention, Fig. 2 is a block diagram showing an embodiment of the arithmetic circuit, and Fig. 3 is a partial cross-sectional view showing an example of a damper. 4 is a partially cross-sectional perspective view showing an example of a flow cell, FIG. 5 is a rough view showing an example of a conductivity signal obtained by a differential amplifier, and FIG. The 717th calibration curve of electrical conductivity and sucrose concentration obtained using the device is a graph showing the stability of measurement when operating by connecting the r'ζ of this invention. 1... ...Reagent pipe line, 2...Sample pipe line, 3
...Cleaning pipe, 4...Switching valve, End...
Mixer, 6...Flow-through type 4 Electrode cell [
)4-cell), 7... Arithmetic processing circuit. Applicant: Fujikogyo Co., Ltd. Figure 2 Figure 5 Figure 6 Wire drawing density (9%) K: Etc.? ! Low X: Low circularity r:, 7 fields red book 0
5 10 15:00 1%
'l (four)

Claims (1)

[Claims] a reagent conduit for conveying a strong electrolyte solution, a sample conduit for conveying a sample liquid, a cleaning conduit for conveying a cleaning liquid, a switching valve for switching between the sample conduit and the cleaning conduit, and a switching valve for switching between the sample conduit and the cleaning conduit; A mixer that uniformly mixes an electrolyte solution and a sample solution or a strong electrolyte solution and a cleaning solution, a flow-through type 4-electrode cell that flows through the measurement liquid mixed in the mixer and measures conductive dust in the measurement liquid, and this flow-through type A total sugar content measuring device comprising an arithmetic processing circuit that calculates and displays sugar content from conductive dust signals from a four-electrode cell.