JPH06105233B2 - How to determine the freshness, maturity and internal quality of fruits and vegetables - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for determining the freshness / ripening degree and internal quality of fruits and vegetables such as fruits and vegetables.

2. Description of the Related Art Currently, at fruits and vegetables collection and sorting facilities, sorting of fruits and vegetables in size, weight, shape, etc. is automated. on the other hand,
Among the quality aspects such as freshness, ripeness, damage, and decay of fruits and vegetables, it is possible to select the damage and decay of the epidermis that can be visually judged by an optical discriminating method. How is it?

Problems to be Solved by the Invention However, there is no effective automatic discrimination method for the freshness and ripeness and the quality of the inside of fruits and vegetables, which are most important for consumers, and it is unavoidable to perform a destructive inspection by sampling and grade the incoming lot. The current situation is that there was a demand for automation.

The present invention has been made in order to meet the above-mentioned conventional requirements, and the purpose thereof is to be able to reliably and quickly automatically determine the freshness / ripening degree and internal quality of fruits and vegetables by an extremely simple method, Means for solving the problem of providing a method for determining the freshness / maturity of fruits and vegetables and the internal quality that can prevent inspection variations and save labor in sorting work Generally, the electrical characteristics of fruits and vegetables. Is, as shown in FIG.
It can be replaced with a parallel equivalent circuit of resistance and capacitance.

The present inventor either sandwiches fruits such as apples, peaches, oysters, tomatoes, etc. between plate-shaped electrodes (which may be formed with a curved concave surface so that they can easily come into contact with the outer surface of the fruits and vegetables) or needles on the fruits and vegetables. The parallel equivalent resistance and parallel equivalent capacitance between the electrodes were measured at various measurement frequencies with the electrodes in the shape of electrodes inserted directly.

As a result, it was difficult to find a certain tendency in the relationship between individual high-frequency capacitance values and high-frequency electrical resistance values and freshness, maturity, and internal quality. as shown, the parallel equivalent resistance value Rf ₁ measured at a certain frequency f _1, the horizontal axis the ratio Rf ₁ / Rf ₂ parallel equivalent resistance value Rf ₂ measured at a higher frequency f ₂ which, on the other hand, the frequency f parallel equivalent capacitance value Cf ₁ when measured in ₁
And the parallel equivalent capacitance value Cf ₂ measured at frequency f ₂ Cf ₁ / Cf
Examining the distribution of many fruits and vegetables of the same type with ₂ as the vertical axis, it was found that there was a tendency for the relationship between freshness and quality of fruits and vegetables and electrical characteristics.

That is, although there are some differences depending on the variety of fruits and vegetables,
As is clear from Fig. 3, Rf is generally the most fresh.
_If the value of ₁ / Rf ₂ is large and internal tissue destruction occurs, Rf ₁ / R
The f ₂ value decreases and Cf ₁ / Cf ₂ increases. Further, Rf ₁ / Rf ₂ the decrease in freshness may occur decreases, of which spoilage occurs Cf ₁ / Cf ₂ is relatively large, shrivel when Cf ₁ / Cf ₂ tends to decrease.

The present invention discriminates the freshness, maturity and quality of fruits and vegetables by applying the above-mentioned principle. The first discrimination method is to set fruits and vegetables between a pair of electrodes and
The equivalent resistance at each frequency is measured by applying electric fields of different frequencies, and the ratio of the equivalent resistances at the two kinds of frequencies is calculated from these measured values, and the calculated value is determined in advance. It is characterized in that the freshness and ripeness of fruits and vegetables are determined in comparison with a standard, and a command signal is input to a display and / or a sorting actuator.
In the second discrimination method, fruits and vegetables are set between a pair of electrodes, an electric field of two kinds of frequencies is applied between the electrodes, and the equivalent resistance and the equivalent capacitance at each frequency are measured, respectively. Equivalent resistance ratio and equivalent capacity ratio are calculated from the measured values, and these calculated values are compared with preset discrimination criteria to determine the freshness, ripeness and internal quality of fruits and vegetables for display and / or selection. It is characterized in that a command signal is inputted to the actuator.

Examples Hereinafter, examples of the present invention will be described with reference to the drawings.

In FIG. 1, 1 and 2 are a pair of electrodes which constitute a sensor section. A fruit 3 such as an apple is sandwiched between these electrodes 1 and 2. The fruits and vegetables 3
In order to reduce the contact resistance between them and each electrode 1 and 2 and to prevent the fruits and vegetables 3 from being scratched,
Felt (or sponge-like substance) impregnated with salt water 1
a and 2a are inserted and attached to each of the electrodes 1 and 2.
To prevent the adherence of salt water to the measurement object, a thinner rubber film may be covered. Further, the electrodes 1 and 2 are rotatably attached to the insulating support portions 4 and 5 via the pivot portions 4a and 5a,
When the fruits and vegetables 3 are set, the inclination angle thereof is automatically adjusted within a predetermined range so that no gap is formed in the contact portion with the fruits and vegetables 3.

The pair of electrodes 1 and 2 can change the measurement frequency
It is connected to the connection terminals 6a and 6b of the C and R meters 6, respectively. There are various measuring methods for the C and R meters 6, but rather than measuring C and R individually, using a vector voltmeter and a vector ammeter, the vector voltage applied to the fruits and vegetables 3 and the inside of the fruits and vegetables 3 are measured. It is desirable that the vector current flowing can be measured and the equivalent parallel capacitance C and the equivalent parallel resistance R between the electrodes 1 and 2 at the same point can be calculated. Needless to say, when measuring only the resistance value as in the first aspect of the invention, the C and R meters 6 are R meters.

The C and R meters 6 are connected to a microcomputer 7 which outputs calculation command signals and calculations for determining freshness and quality of fruits and vegetables.

Further, the microcomputer 7 is connected to a display 8 for displaying quality and an actuator 9 for selecting.

Next, a method of determining freshness / quality by the above device will be described.

First, before setting the fruits and vegetables 3 between the electrodes 1 and 2, the residual impedance and the floating admittance between the electrodes 1 and ₂ at the constant frequencies f ₁ and f ₂ on each side were measured once and used as zero offset data. It is prepared so that the equivalent parallel capacitance C and the equivalent parallel resistance R of only the fruits and vegetables 3 can be measured.

When the fruits and vegetables 3 are set between the electrodes 1 and 2, the first measurement frequency f is set between the electrodes 1 and 2 by a command from the microcomputer 6.
An electric field of ₁ (100Hz to 100KHz: preferably about 10KHz) is applied, the vector voltage applied to the fruits and vegetables 3 and the vector current flowing therein are measured, and the samples corresponding to f ₁ are paralleled in the C and R meters 6. The equivalent capacitance CF ₁ and the parallel equivalent resistance Rf ₁ are measured.

Next, an electric field of the second measurement frequency f ₂ (preferably about 100 KHz to 100 MHz: 1 MHz) is applied between the electrodes 1 and 2 by a command from the microcomputer 7, and the fruits and vegetables 3 corresponding to f ₂ are also applied.
The parallel equivalent capacitance Cf ₂ and the parallel equivalent resistance Rf _{2 of} are measured.

These measurement data are sent to the microcomputer 7, and the parallel equivalent capacitance C measured at different measurement frequencies f ₁ and f ₂ is used.
The ratio Cf ₁ / Cf ₂ of the ratio Rf ₁ / Rf ₂ parallel equivalent resistance R measured at different measuring frequencies f ₁ and f ₂ is calculated.

Then, the microcomputer 7 was previously tested with experimental data.
According to the criteria for the relationship between the areas of Cf ₁ / Cf ₂ and Rf ₁ / Rf ₂ and the freshness / quality of the fruits and vegetables 3 (see FIG. 4) stored in FIG. ₁ / Rf ₂ , Y = Cf
_The computer 7 compares and determines which quality region A to D the coordinates (X, Y) of ₁ / Cf ₂ are in, or which region is closest, and determines the quality.

The determination result is output to the display 8 and also as a signal for operating the actuator 9 for selection.

Next, the high-frequency parallel equivalent capacitance ratio Cf ₁ / Cf ₂ and the high-frequency parallel equivalent resistance ratio of fruits and vegetables actually measured using the apparatus of the above embodiment
Examples of measurement of Rf ₁ / Rf ₂ are shown in FIGS. 4 and 5.

Fig. 4 shows the case of apple, and the measured frequency
f ₁ is 10 KHz and f ₂ is 1 MHz.

A region A in which the parallel equivalent resistance ratio Rf ₁ / Rf ₂ is relatively large is a region in which the freshness of apples is high. When this apple with high freshness is dropped on the floor several times and the inside is damaged (in the case of an apple, the inside of the apple immediately changes to brown due to the impact of falling), its coordinates (X, Y) = (R _10K / R _1M , C _10K / C _1M ) values moved to region B. Area C where the freshness is further reduced and rotten
He also entered area D.

FIG. 5 shows the case of determining the maturity of tomatoes. Tomatoes with a certain degree of bluishness are in region E, tomatoes ripe in red are in region F, tomatoes that have become red and overripe are in region G. It is included.

In addition, f _{1 of the} above measurement frequency is (100 Hz to 100 KHz) and f ₂
Has been set to (100KHz~100MHz), f _2, it is desirable to select the f ₁ and f ₂ such that the frequency of 10 times or more of the f _1.

Also, instead of the X-axis resistance ratio R _10KHZ / R _1MHZ , the absolute value of the vector impedance Z | Z | = R Cosθ ratio _Can be judged to some extent, but the resistance ratio R _10KHZ / R
_1MH had higher accuracy in determining freshness.

Furthermore, X / Y = (Rf ₁ / Rf ₂ ) / (Cf ₁
/ Cf ₂ ) can be used as the comprehensive freshness judgment value.

Effect of the Invention Instead of conventional destructive inspection by sampling, non-destructive method is used to prevent loss of commercial value of fruits and vegetables.
It is possible to accurately and promptly and automatically determine internal damage, decay, etc., prevent inspection variations, and save labor in sorting work.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic diagram of a vegetable and fruit quality judging apparatus for carrying out the method of the present invention, FIG. 2 is a diagram showing an equivalent circuit of fruits and vegetables and their electrical characteristics, and FIG. 3 is an electrical characteristics of fruits and vegetables. 4 is a graph showing a measurement example of apples, and FIG. 5 is a graph showing a measurement example of tomatoes. 1, 2 ... Electrodes, 1a, 2a ... Felt, 3 ... Fruit and vegetables, 4,5 ... Insulation support part, 4a, 5a ... Pivoting part, 6 ... C, R meter, 7 ... Microcomputer, 8 ... Quality display, 9 ... sorting actuator, C ... equivalent parallel capacitance, R ... equivalent parallel resistor, f ₁ ... the first measurement frequency, f ₂ ... second measurement frequency, Z
… Impedance, θ… Phase angle.

Claims (2)

[Claims] 1. A fruit or vegetable is set between a pair of electrodes, an electric field of two kinds of frequencies is applied between the electrodes, and an equivalent resistance at each frequency is measured, and an equivalent resistance ratio is calculated from these measured values. Freshness of fruits and vegetables characterized by calculating and comparing the calculated value with a preset discrimination criterion to determine the freshness and ripeness of fruits and vegetables, and inputting a command signal to a display and / or a sorting actuator. -A method for determining maturity and internal quality. 2. Fruits and vegetables are set between a pair of electrodes, an electric field of two kinds of frequencies is applied between the electrodes, an equivalent resistance and an equivalent capacitance at each frequency are measured, and an equivalent value is obtained from these measured values. The resistance ratio and equivalent capacity ratio are calculated respectively, and these calculated values are compared with preset discrimination criteria to determine the freshness, ripeness and internal quality of fruits and vegetables, and a command signal is sent to the display and / or the sorting actuator. The freshness of fruits and vegetables characterized by entering
How to determine maturity and internal quality.