JPH0629868B2 - Freshness judgment method by contact and non-contact of fruits and vegetables - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for determining the freshness of fruits and vegetables such as fruits and vegetables by contact and non-contact.

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, sugar content, 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 discrimination method. Most of them.

However, there is no effective automatic judgment method for the internal quality of fruits and vegetables, which is the most important for consumers, and it is unavoidable that the lots are rated by destructive inspection by sampling. There was a request for automation.

The present invention has been made in order to meet the above-mentioned conventional demands, and its object is to be able to reliably and quickly automatically determine the internal quality such as freshness and ripeness of fruits and vegetables by an extremely simple method. The object of the present invention is to provide a freshness judging method by contact and non-contact of fruits and vegetables, which can prevent variation in inspection and save labor in sorting work.

Means for Solving Problems (1) The electrical characteristics of fruits and vegetables can be replaced with a parallel equivalent circuit of a resistor R and a capacitor C or a series equivalent circuit as shown in FIG.

The present inventor has made a disc-shaped test piece cut out from fruits and vegetables such as apples, peaches, oysters and tomatoes and sandwiched between the electrodes, or a needle-shaped electrode is directly inserted into the fruits and vegetables, and the electrodes are arranged in parallel. The resistance and the parallel equivalent capacitance and the series equivalent resistance and the series equivalent capacitance were measured at various measurement frequencies.

As a result, in general, series equivalence due to the decrease in freshness of fruits and vegetables,
It has been found that the resistance value tends to decrease and the capacitance value tends to increase regardless of the parallel equivalence.

On the other hand, in order to measure the resistance and the capacitance of the whole fruits and vegetables in a non-destructive manner, as shown in FIG. 1, the fruits and vegetables are placed directly on the surfaces of the V-shaped metal electrodes 1 and 2, and the electrodes and When the parallel equivalent resistance R _p , parallel equivalent capacitance C _p , series equivalent resistance R _s , and series equivalent capacitance C _s of the
Parallel equivalent resistance R _p , parallel equivalent capacitance depending on the contact state of the surface of
It was found that the measured values of C _p and the series equivalent capacitance C _s were greatly varied.

In order to reduce the variation, it was necessary to closely sandwich a sponge-like electrode impregnated with salt water between the electrodes 1 and 2 and the fruits and vegetables 3.

However, regarding the series equivalent resistance R _s , even if the fruits and vegetables 3 are directly placed on the surfaces of the metal V-shaped electrodes 1 and 2 and the measurement is performed in an uncertain contact state, the variation is other than the above measured values.
It was found that it was extremely small compared to R _P , C _P , C _S. That is, the series equivalent resistance value is less affected by the contact state than the other measured values C _S.

Figure 4 is obtained by measuring the equivalent series resistance and reactance of the needle electrode to the plug 10Hz~10MHz for different None (twentieth century) freshness, horizontal axis represents the equivalent series resistance R _S, apparently freshness The series equivalent resistance is remarkably reduced due to the decrease.

Fig. 5 shows a pear of different freshness (twentieth century) using V-shaped electrodes 1 and 2 shown in Fig. 1, and non-destructively setting the series equivalent resistance R _S to 1
It was measured from 0 KHz to 10 MHz, and it was found that in this case as well, the series equivalent resistance (logarithmic display) was remarkably decreased due to the decrease in freshness, and the reproducibility was also good. That is, the pear with a high degree of freshness indicated by a circle is in the area A, most of the pears with a low degree of freshness indicated by a triangle is in the area B, and the partially decomposed pear indicated by a ● and the drop impact indicated by a cross. It was found that most of the pears that had received damage and had internal damage entered region C.
Although not shown, apples and the like have a similar tendency.

(2) At frequencies above 1MHz, the number between the electrode and the fruit
Resistance can be measured by capacitive coupling even if a gap of about mm is provided and one side or both sides are in non-contact state. FIG. 6 shows the effect of the size of the oyster on the series equivalent resistance R _S when the upper electrode 11 is not contacted at 13 MHz. The fruits and vegetables 3 are placed directly on the lower electrode 10. In this case, in order to perform a stable measurement, if the position of the upper electrode 11 is fixed, the influence of the fruit diameter is remarkable, and even if the oysters of the same maturity as the broken line in the figure have, the series equivalent resistance R _S between the electrodes 10 and 11 is increased.
Is different. Therefore, when the positions of the electrodes 10 and 11 are controlled so that the series equivalent capacitance C _S measured at the same time is kept constant (2 μF), the influence of the fruit diameter is reduced as shown in (solid line in the figure), and the accurate determination of the ripeness is made. Can be done.

[Embodiment] An embodiment of the present invention will be described below with reference to the drawings.

In FIG. 1, reference numerals 1 and 2 are a pair of electrodes, which form a sensor section. These electrodes 1 and 2 are V-shaped and can be measured simply by placing a fruit 3 such as an apple on it. Even if there is a slight difference in size between the fruits and vegetables 3, it can be measured at any position of the V-shaped electrodes 1 and 2 and the gap between the electrodes 1 and 2 can be fixed. Further, as shown in FIG. 2, the V-shaped electrodes 4 and 5 may be formed in a trough shape, and the fruits and vegetables 3 may be rolled on the trough shape for measurement.

The pair of electrodes 1 and 2 are connected to the connection terminals 6a and 6b of the impedance meter or the C and R meters 6, respectively. There are various measuring methods for the C and R meters, but not only those that can directly measure the series equivalent resistance R _S , but also the parallel equivalent resistance R _P and the parallel equivalent capacitance C _P , and then the series equivalent resistance It may be of a format that can calculate R _S.

In the case of an impedance meter, the vector impedance can be measured by measuring the vector voltage applied to the fruits and vegetables 3 and the vector current flowing in the fruits and vegetables 3 by using a vector voltmeter and a vector ammeter. A resistance value may be used as an output, and an impedance meter is easier to measure than a CR meter. Therefore, the case of using an impedance meter will be described below.

The impedance meter 6 is connected to a microcomputer 7 which outputs calculation command signals and calculations for freshness / quality determination 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.

When the fruits and vegetables 3 are set between the electrodes 1 and 2, an electric field of a predetermined measurement frequency is applied between the electrodes 1 and 2 according to a command from the microcomputer 6, and a vector voltage applied to the fruits and vegetables 3 and a vector flowing therein. The current is measured and the series equivalent resistance R _{S of the} sample is measured.

This measurement data is sent to the microcomputer 7, and then compared by the computer 7 in accordance with the judgment criteria of the relation between the freshness / quality of the fruits and vegetables 3 and the series equivalent resistance, which are stored in the microcomputer 7 in advance based on the experimental data. Make a judgment and judge its quality.

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

It should be noted that an electric field of two kinds of frequencies is applied between the electrodes 1, 2, or 4, 5 to calculate the ratio of series equivalent resistance at each frequency or the ratio of series equivalent capacitance, and calculate these values. May be compared with the discrimination criterion.

Advantages of the invention (1) Instead of the conventional destructive inspection by sampling, non-destructive method that does not lose the commercial value of fruits and vegetables should be used to accurately and promptly and automatically judge the freshness, ripeness, internal damage, decay, etc. Therefore, it is possible to prevent variations in inspection and save labor in sorting work.

(2) Regardless of the size of the fruits and vegetables, the V-shaped electrode can be simply placed on top of it to pinch the fruits and vegetables, and conductive substances such as salt water can be measured without adhering to the fruits and vegetables.

(3) The series equivalent resistance, which is the criterion, is not easily affected by the contact state between the fruits and vegetables and the electrodes, and can be measured even in the uncertain contact state where the fruits and vegetables are simply placed on the electrodes.

[Brief description of drawings]

FIG. 1 is a schematic diagram of a vegetable and fruit quality judging device for carrying out the present invention, FIG. 2 is a diagram showing a modified example of an electrode, FIG. 3 is a diagram showing an equivalent circuit of fruits and vegetables and their electrical characteristics, and FIG. Fig. 5 is a graph showing the electric characteristics and tendencies of freshness and quality, Fig. 5 is a graph showing a measurement example of 20th century pear, and Fig. 6 is a graph showing a measurement example of oyster. 1, 2 ... Electrode, 3 ... Fruits, 4, 5 ... Electrode, 6 ... Impedance meter or C, R meter, 7 ... Microcomputer, 8 ... Quality display, 9 ... Selection actuator, 10, 11 ... Electrode.

Claims (2)

[Claims] 1. Fruits and vegetables are set in contact with each other on a pair of V-shaped electrodes, and an AC voltage is applied between the electrodes.
A series equivalent resistance between the electrodes is measured, the measured value is compared with a preset determination criterion to determine the internal quality of the fruits and vegetables, and a command signal is input to the display and / or the sorting actuator. Method for determining freshness by contact and non-contact of fruits and vegetables. 2. Fruits and vegetables are set between a pair of electrodes installed above and below, a high-frequency electric field is applied between the electrodes, the series equivalent capacitance and series equivalent resistance between the electrodes are measured, and the series equivalent capacitance value is measured. Determine the internal quality of fruits and vegetables by comparing the measured value of the series equivalent resistance in the state of controlling the upper electrode position so as to keep it at a predetermined value with a preset criterion,
A method for determining freshness by contact or non-contact of fruits and vegetables, characterized by inputting a command signal to a display and / or a sorting actuator.