JPS6385342A - Method for classifying internal quality of vegetables and fruits having arbitrary shape - Google Patents

Abstract

PURPOSE:To discriminate and classify the internal quality of vegetables and fruits regardless of the size and shape thereof, by measuring the electric constant of vegetables and fruits between electrodes in an immersion liquid and comparing the same with the electric constant of the immersion liquid. CONSTITUTION:An insulating container having a pair of electrodes 1, 2 provided to both side walls thereof is filled with an immersion liquid 4 having definite resistivity, and vegetables and fruits 5 to be measured are immersed in the liquid. When the resistivity of the vegetables and fruits 5 is higher than that of the liquid 4, the resistance between the electrodes 1, 2 becomes larger than that when only the liquid is present and, when the resistivity of the vegetables and fruits 5 is lower than that of the liquid 4, the resistivity between the electrodes 1, 2 is lowered by the immersion of the vegetables and fruits 5. The increment and decrement of this resistance between the electrodes is different depending on the size of the vegetables and fruits 5 but the change direction thereof has no relation to the size or shape of the vegetables and fruits 5. When the vegetables and fruits are desired to be classified into a plurality of ranks, as many containers having immersion liquids having resistivities to serve as the threshold values thereof are prepared as the number of classifying ranks and classification is performed on the basis of the increment and decrement DELTAR of the resistances between the electrodes before and after immersion.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is a method for measuring internal quality such as freshness, ripeness, sugar content, damage, and spoilage of fruits and vegetables of any shape based on differences in their size and shape. Regardless, it relates to a method of determining and classifying fruits and vegetables based on their resistivity or dielectric constant, or the number of microwaves loaded or the phase constant.

[Prior art and its problems] Currently, in fruit and vegetable collection and sorting facilities, among the quality aspects of fruits and vegetables such as freshness, ripeness, sugar content, acidity, damage, and rottenness, it is necessary to screen for skin damage and rottenness that can be determined by appearance. is possible using an optical discrimination method.

However, the most important factors for consumers are freshness, ripeness, sugar content,
Currently, there is no effective automatic method for determining the internal quality of fruits and vegetables, such as internal damage, and it is unavoidable to perform destructive inspections using sampling to grade incoming lofts, and there has been a demand for automation.

In recent years, internal qualities such as freshness, ripeness, sugar content, and spoilage of fruits and vegetables have been shown to correspond to complex dielectric constants such as the permittivity and resistivity (or conductivity) of fruits and vegetables in a certain frequency range, or the attenuation constant and phase constant of microwaves. Utilizing the correlation with electrical material constants, the internal quality of fruits and vegetables can be measured by measuring the capacitance and electrical resistance of fruits and vegetables between electrodes, or the amount of attenuation and phase of microwaves due to fruits and vegetables between transmitting and receiving antennas. Techniques are being developed to evaluate

The most difficult problem in such electrical measurements is that many fruits and vegetables have complex shapes, and even specific fruits and vegetables vary in size and shape. The problem lies in the fact that the capacitance, electrical resistance, or the amount of attenuation and phase of microwaves are greatly influenced by the size and shape of the fruits and vegetables, in addition to the permittivity and resistivity of the fruits and vegetables themselves, or the attenuation constant and phase constant of the microwaves.

Therefore, in order to determine the permittivity and resistivity of fruits and vegetables, it is necessary to separately measure the size and shape and use that data to perform complex correction calculations, or to use methods such as CT, but it is difficult to judge the quality of fruits and vegetables. Because these methods are not suitable for processing due to processing time and cost, there is a need for a simple method that can accurately measure the dielectric constant and resistivity of fruits and vegetables, regardless of their size, weight, or shape. It was getting worse.

Furthermore, in general, the electrical characteristics of fruits and vegetables can be replaced by a parallel equivalent circuit of resistance and capacitance corresponding to their complex permittivity.

The inventor of the present invention calculated the parallel equivalent resistance and parallel equivalent capacitance between the electrodes by sandwiching fruits and vegetables such as apples, peaches, oysters, and tomatoes between plate-shaped electrodes, or inserting needle-shaped electrodes directly into the fruits and vegetables. Measurements were made at various measurement frequencies.

Now, use 4 needle-like electrodes with a thickness of 2 mm and a length of 20 III LI1.
Insert it into the apple with a spacing of 0+a+a, and make the capacitance (parallel equivalent) and electrical resistance (parallel equivalent) between the electrodes 1
00H7. An example of measurement up to IOMHZ is shown in FIG.

Generally, the resistivity of fruits and vegetables decreases due to tissue destruction and decay, but in this case, due to complete decay, the resistance R between the electric current F@ is about 1710.

Using this destructive measurement method, it is possible to accurately measure the electrical properties, but when measuring non-destructively by contacting an electrode from the outside of the fruit, it is affected by the size and shape of the fruit. At the same time, the contact resistance between the pericarp and the electrode fluctuates, making it difficult to measure small differences in resistivity. Also,
In contact measurement, fruits and vegetables may be damaged due to detachment of the electrode.

Therefore, a non-contact, non-destructive method for accurate measurement is needed.

[Object of the invention] The present invention has been made in view of the above-mentioned conventional problems, and
The purpose of this is to use a non-destructive, non-contact, and extremely simple method to produce products ranging from simple shapes such as watermelons and melons that differ only in size to those that have a constant size and shape, such as eggplants and potatoes. Regardless of the size or shape of fruits and vegetables, we can accurately measure and classify their permittivity and resistivity, and determine the freshness and ripeness of fruits and vegetables, even for fruits and vegetables that do not grow or have complex shapes such as spinach. An object of the present invention is to provide an internal quality sorting method for fruits and vegetables of arbitrary shapes, which can be applied to automatic determination of internal quality such as sugar content, sugar content, damage, etc., which can prevent variations in inspection and save labor in sorting work. .

[Structure 1 of the Invention The internal quality sorting method for arbitrarily shaped fruits and vegetables of the first invention utilizes the fact that the internal quality of fruits and vegetables correlates with their electrical material constants, and the method uses the fact that the internal quality of fruits and vegetables correlates with their electrical material constants, Alternatively, in a system that measures the microwave attenuation and phase between transmitting and receiving antennas in an immersion liquid to determine and classify its internal quality, the internal quality of fruits and vegetables is determined by comparing it with the electrical material constants of the immersion liquid.・It is characterized by being divided into sections, and its first embodiment is one equipped with measurement electrodes.
Depending on the rank of resistivity or permittivity of the fruit or vegetables you want to sort, fill immersion liquid with a threshold resistivity or permittivity in two or more containers, and measure the resistance between the electrodes before and after soaking the fruit or vegetables. This method is characterized by determining and classifying internal quality based on increases and decreases in electric capacitance. In a second embodiment, a container equipped with measurement electrodes is filled with a standard immersion liquid, and vegetables and fruits are immersed in the container. When the measuring frequency is swept under the condition that the measuring frequency is swept, the internal quality of fruits and vegetables is determined and classified by the frequency at which the resistance or capacitance between the electrodes is the same as in the case of only the immersion liquid. In the embodiment of 3, in one or more containers equipped with transmitting and receiving antennas, attenuation chambers WL* or phase are set as a threshold value depending on the rank number of the attenuation constant or phase constant of fruits and vegetables to be sorted. The method is characterized in that each device is filled with an immersion liquid having a constant value, and the internal quality is determined and classified based on the increase or decrease in the microwave attenuation or phase amount between the transmitting and receiving antennas before and after immersing the fruits and vegetables. In this case, when a standard immersion liquid is filled in a container equipped with transmitting/receiving antennas and the measurement frequency is swept with fruits and vegetables immersed, the microwave attenuation between the antennas is equal to that in the case of only the immersion liquid, or Determine the internal quality of fruits and vegetables using the frequency that is the phase amount.
It is characterized by being divided into sections.

[Example] Hereinafter, an example of the present invention will be described with reference to the drawings.

As shown in FIG. 1, an immersion liquid 4 having a constant resistivity is filled in an insulating container 3 having a pair of electrodes 1°2 on both side walls.
Fruits and vegetables 5 to be measured are immersed in this dipping liquid 4.

However, the water level before and after immersion is kept constant by means such as the over 70-pipe 6.

When the resistivity of the fruits and vegetables 5 is greater than the resistivity of the immersion liquid 4, the resistance between the electrodes 1 and 2 will be greater than when only the immersion liquid 4 is used. If the resistance is smaller than the ratio, the resistance of the electrode 1.2 is lowered by immersion of the fruits and vegetables 5.

While this increase/decrease in the inter-electrode resistance varies depending on the size of the fruit or vegetable 5, the direction of change is not related to the size or shape of the fruit or vegetable 5.

Therefore, when it is desired to classify many fruits and vegetables into a plurality of ranks based on their resistivity, as shown in FIG. ρ2. ρ,...
A container containing immersion liquid of (ρ1〉ρ2〉ρ,...)
It is sufficient to prepare them according to the number of ranks to be classified and to classify them according to the sign or negative of the increase/decrease ΔR in the interelectrode resistance before and after immersion. When fresh fruits and vegetables that are not overripe are immersed in an immersion solution with a resistivity of ρ1, the interelectrode resistance increases, so they should be ranked as rank A. If the interelectrode resistance decreases, the next lower resistivity is ρ2. They are placed in an immersion liquid of rank B or resistivity ρ, depending on the increase or decrease in the interelectrode resistance, and the rotten ones remain at the end.

The immersion liquid 4 may be water, and if an electrolyte such as common salt is added to it, the conductivity will increase and the resistivity will decrease, so the resistivity can be easily adjusted to ρ by changing the concentration of the common salt. You can adjust ρ.

A square plate-shaped electrode 1.2 of 75 m x 75 mte was installed in a cubic container 3 with an internal diameter of 85 m as shown in FIG.

Table 1 shows the measured values of interelectrode resistance when each defeated apple was immersed. In this case, the measurement frequency is 63KHz,
The immersion liquid was tap water, and the threshold resistivity was measured separately and was 4.9 Ω・c theory (conductivity 20, 4 m
s/m).

Table 1 Electrical Resistance and Changes Between Electrodes According to Table 1, the resistance between electrodes increases when fresh apples are immersed, and the resistance between electrodes decreases when internally damaged or rotten apples are immersed.

In addition, in the case of discrimination based on dielectric constant, it is exactly the same, instead of measuring the interelectrode resistance R, the electrode opening fi C is measured, and the increase/decrease ΔC in the interelectrode capacitance due to immersing fruits and vegetables in the immersion liquid is determined, and the ranking is determined. In this case, a higher concentration of salt water is required than when measuring resistance.

Furthermore, microwaves are used to measure the sugar content and acidity of fruits and vegetables, and in principle, the above method can be applied because they are related to the sterile constant and phase constant corresponding to the complex permittivity of fruits and vegetables. I can do it.

That is, as shown in FIG. 3, the transmitting antenna 7 is used instead of the electrode.
It is sufficient to measure the attenuation amount or phase amount of the microwave between them using the receiving antenna 8 and the receiving antenna 8. Using the case of only the soaking liquid 4 as a threshold value, judgment is made based on the increase or decrease in the amount of attenuation or phase amount due to soaking the fruits and vegetables 5. , can be ranked.

Furthermore, in the apparatus shown in FIG. 1, when the measurement frequency is swept from 10 KHz to 1000 KHz with an apple immersed, the interelectrode resistance R changes as shown in FIG. 4. Song #i (a) is a case of only tap water with a resistivity of 4°9 and Ω・cIl (conductivity of 20, 411 Is/m), and the frequency characteristics of resistivity are hardly seen in this frequency range. .

When a fresh, large apple is dipped in this, the apple has a large frequency characteristic, so the overall frequency characteristic including the apple and the soaking liquid becomes like a curve (b). Let the intersection of curve (b) and curve (a) be A, and its frequency be "A.

Next, when a small fresh apple is soaked, a curve (C) is obtained, but the A of the same frequency f^ as these songs #i (A) is obtained.
Intersect at a point.

On the other hand, when a large rotten apple is immersed, its resistivity is low, so the frequency characteristic of the interelectrode resistance becomes curve (d), which intersects curve (a) at point B of frequency fe. ) also intersects at the frequency 1 day) where B points.

In other words, fresh food, regardless of its size or shape,
The frequency fA equal to the resistivity of the immersion liquid (in this case 9
It intersects with the characteristic surface m (a) of only the immersion liquid at a frequency of 0 KHz), and the characteristic surface m (a) of only the immersion liquid intersects with the curve (a) at a lower frequency of 1 day (in this case, 50 KHz) for the one whose resistivity has become low.

Therefore, by immersing fruits and vegetables and finding the frequency at which the interelectrode resistance is equal to that in the case of only the immersion liquid (hereinafter referred to as the cross frequency), it is possible to know the freshness and ripeness of the fruit. If the intersection frequency is high, it is fresh; if it is low, it is overripe, damaged, or rotten.

To find the intersection frequency, you can sequentially sweep the frequencies during resistance measurement and find the frequency when ΔR = 0, but since the range of the intersection frequency is determined by the type of fruit and the resistivity of the soaking liquid, It is quick to measure the resistance R at two or three frequencies before and after that, use a computer to interpolate between them, and find the intersection with the curve (A).

In this method, fruits and vegetables can be classified into many ranks using one type of dipping liquid simply by finely dividing the threshold value of the intersection frequency f using computer software.

This method can also be applied as is to the measurement of electric capacity or the amount of microwave reduction and phase by increasing the salt concentration of the immersion liquid.

[Effects of the invention] (1) Electrical resistance and capacitance between electrodes, transmitting and receiving antenna -
In a system that evaluates the internal quality of fruits and vegetables by measuring the amount of microwave attenuation and phase between It is possible to determine the internal quality of fruits and vegetables and classify them.

(2) Even products with complex shapes such as eggplants, cucumbers, potatoes, and spinach can be processed non-destructively by simply immersing them in the soaking liquid and comparing the resistivity and dielectric constant of the soaking liquid with those of the fruits and vegetables.
Accurate discrimination and classification is possible without contact.

(3) Since the comparison is made with the resistivity, dielectric constant, etc. of the immersion liquid, there is very little discrimination error due to misalignment in the relative position of the fruit or vegetable and the electrode or antenna.

(4) By adjusting the resistivity and dielectric constant of the immersion liquid, or the attenuation constant and phase constant of the microwave, which are the threshold values, by adding an electrolyte, such as salt, it is possible to set the threshold value to an arbitrary value. , and the frequency used for measurement can also be freely selected.

(5) If the intersection frequency is used as the determination value, one immersion liquid can be divided into many ranks. Alternatively, the judgment can be made while flowing fruits and vegetables together with the soaking liquid in the pipe.

[Brief explanation of the drawing]

Fig. 1 is a schematic explanatory diagram of the measuring device of the present invention, Fig. 2 is a diagram explaining the method, Fig. 3 is a schematic explanatory diagram showing measurement using microwaves, and Fig. 4 is a diagram showing the distance between electrodes in an immersed state. Graph showing frequency characteristics. FIG. 5 is a graph showing electrical characteristics of an apple using a needle electrode. 1.2... Electrode, 3... Container, 4... Immersion liquid, 5
... Fruits and vegetables, 6... Over 70-tube, 7... Transmitting antenna, 8... Receiving antenna.

Claims (5)

[Claims] (1) Utilizing the fact that the internal quality of fruits and vegetables correlates with their electrical material constants, measure the electrical resistance and capacitance of fruits and vegetables between electrodes, or the amount of microwave attenuation and phase between transmitting and receiving antennas in an immersion liquid. A method for sorting the internal quality of fruits and vegetables of any shape, characterized in that the internal quality of the fruits and vegetables is determined and classified by comparing with the electrical material constant of the soaking liquid, in the system for determining and classifying the internal quality. (2) Fill one or more containers equipped with measurement electrodes with an immersion liquid that has a resistivity or dielectric constant that is a threshold value depending on the rank of resistivity or dielectric constant of the fruits and vegetables you want to classify. 2. The internal quality sorting method for fruits and vegetables of arbitrary shape according to claim 1, characterized in that the internal quality is determined and classified based on the increase or decrease in resistance or capacitance between electrodes before and after soaking the fruits and vegetables. (3) When a container equipped with measurement electrodes is filled with a standard immersion liquid and the measurement frequency is swept with fruits and vegetables immersed, the frequency at which the inter-electrode resistance or capacitance is the same as in the case of only the immersion liquid Determine the internal quality of fruits and vegetables using
2. A method for internal quality sorting of fruits and vegetables of arbitrary shape according to claim 1, characterized in that said fruits and vegetables are divided into sections. (4) In one or more containers equipped with transmitting and receiving antennas, each soaking liquid has an attenuation constant or a phase constant that is a threshold value, depending on the rank number of the attenuation constant or phase constant of the fruits and vegetables to be sorted. Meet and send fruits and vegetables before and after soaking
2. The internal quality sorting method for arbitrarily shaped fruits and vegetables according to claim 1, characterized in that the internal quality is determined and classified based on an increase or decrease in microwave attenuation or phase amount between receiving antennas. (5) When a standard immersion liquid is filled in a container equipped with transmitting and receiving antennas, and the measurement frequency is swept with fruits and vegetables immersed, the inter-antenna microwave attenuation or phase is the same as in the case of only the immersion liquid. 2. The internal quality sorting method for fruits and vegetables of arbitrary shape according to claim 1, characterized in that the internal quality of the fruits and vegetables is determined and classified based on the frequency that corresponds to the quantity.