JPS6228649A - Sugar content measuring instrument - Google Patents

Abstract

PURPOSE:To non-destructively measure the sugar content of a fruit by providing an instrument to irradiate a microwave to a fruit and to measure the wave scattered therefrom, comparing the value estimated from the assumed value of the attenuation coefft. of the fruit and the actually measured value and estimating the sugar content of the fruit. CONSTITUTION:The microwave emitted from a microwave oscillator 34 is radiated from an antenna 32 to the fruit 31 through a demultiplexer 35 and the wave reflected from the fruit is received by the antenna 32. The incident wave and the reflected wave are compared by a computer 38 via a receiver 37 by which the distance up to the fruit 31 is calculated. The distance from the antenna 33 is similarly calculated and the outside shape of the fruit 31 is known. The microwave radiated from the antenna 32 is received through the fruit 31 by an antenna 31 and the attenuation quantity thereof is measured. The measured value is compared with the value assumed from the outside shape in the computer 38 and the attenuation coefft. of the fruit 31 is corrected. The sugar content of the fruit 31 is calculated by repeating such process.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a sugar content measuring device for non-destructively measuring the sugar content of plants, particularly mature fruits.

[Background of the invention]

There are differences in plant quality between fruit and leafy vegetables, including appearance, shape, two colors, gloss, aroma, freshness of 2M degrees, and acidity.

Refers to a very wide range of contents such as chemical components such as vitamins and minerals. Among these, sugar content is extremely important as an indicator of quality for fruits and vegetables. However, conventional devices do not destroy sugar content, as shown in ``Wakayama Orchard Experiment: ``Identification of Pericarp Color and Pericarp Damage by Quantifying Reflection of Different Wavelengths'', Core Joint Research Results Report, March 1980''. If you try to measure it directly, you quantify the color of the peel and indirectly estimate the viscosity. The sugar content estimation accuracy of such a device is not sufficient to withstand screening. Therefore, at present, viscosity cannot be measured except by means such as a refractometer that destroys the fruit and measures it.

[Purpose of the invention]

An object of the present invention is to provide a viscosity measuring device capable of non-destructively measuring the sugar content of fruit.

[Summary of the invention]

The present invention focuses on the fact that sugar content has a strong correlation with dielectric constant, and is characterized by a configuration in which the sugar content of the part of the fruit pulp that is the target of taste is directly measured using microwaves.

Figure 1 shows the relationship between viscosity and dielectric constant. In this experiment, a solution consisting of distilled water and sucrose was placed in a glass cell, the glass cell was placed between transmitting and receiving antennas, and the relationship between the amount of attenuation and the sugar content was observed. The frequency is 2.6 GHz, and around this frequency the amount of attenuation corresponds to the dielectric constant. The amount of attenuation is based on the amount of attenuation when the aqueous solution is removed from this cell and replaced with air.

In this way, there is an extremely good correlation between the sugar content and the dielectric constant (attenuation amount) of microwaves. Therefore, it should be possible to estimate the viscosity from the measurement of the amount of attenuation.

Fruits are composed of pericarp, pulp, core, etc., but there is not a uniform correlation between these tissues depending on the fruit, and the sugar content of the pulp cannot necessarily be estimated from the amount of attenuation of microwaves passing through the fruit. Therefore, there is a need for a method to measure the attenuation (permittivity) of only the fruit pulp without being affected by the fruit skin or fruit core.

In the present invention, fruits are irradiated with microwaves and the amount of attenuation of the scattered waves is measured from multiple directions. The dielectric constants (attenuation coefficients) of the pericarp, pulp, and core are determined from these measured data, and the principle will be explained using a virtual fruit with a double cylinder structure shown in FIG. 2.

The microwaves emitted by the transmitting antenna spread in a fan-like manner, but scattering at the interface between the peel and pulp can be considered to approximately follow the laws of geometric optics.

The attenuation coefficient of the medium between the fruit and the antenna, the pericarp, and the pulp is α5. α1. Each beam path length is QwrQ
Let g+QX. The calculated attenuation g (dB), omitting the reflection loss and directivity of the interface, is: g=200ogCαX”X+αgilt+αw Q w
) ” '・'・---(1) The beam path can be uniquely determined by determining the attenuation coefficient. For simplicity, we will write G in parentheses.

α engineering, α5. α is an unknown quantity, but g or G can be measured. Let G be the measured value of G. Now α1. α1. α
Calculate G starting from the initial value (virtual value) of 9, and
If we correct it according to the following rule, we get (α, +ΔαX)・Qx+(α1+Δαg)・f1g+
(α+Δαw)・fl w=G・・・・・・・・・
...(5) The present invention is based on this principle, and the present invention provides fruit skin and fruit pulp.

Assuming the dielectric constant (attenuation constant) of the fruit core, etc., the viscosity of the fruit pulp is estimated by repeated asymptotic calculations.

The dimensional ratio of the pericarp, pulp, and core is determined in advance using preliminary information obtained through destructive measurements. Depending on the fruit, there is no need to assume the fruit core.

It can be treated the same as fruit pulp.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to FIG. The fruit 31 is an antenna 32. Set between the antennas 33.

First, it is necessary to know the size of the fruit, and in this example, based on the same principle as radar, a method of estimating it from the phase and propagation time of radio waves returned from an antenna that irradiates microwaves is shown. The microwaves emitted from the micro oscillator 34 pass through a splitter 35 and are radiated from the antenna 32 to the fruit. The reflected wave passes through splitters 35 and 36, enters the receiver 37, and is compared with the incident wave to calculate the distance between the antenna 32 and the fruit 31.

Next, the output of the oscillator 34 passes through splitters 35 and 36, and microwaves are irradiated from the antenna 33 to the fruit, and the reflected waves are received by the same antenna and guided to the splitter 36 and receiver 37.

With this, the distance between the antenna 33 and the fruit 31 is calculated.

When the cross section of the fruit deviates from a circular shape, the outer shape of the fruit can be determined by rotating the fruit.

Through the above processing, a fruit-antenna attenuation calculation model can be created. The external shape of the fruit is known, and a damping calculation model can be created from the foreknowledge of the fruit, that is, the dimensional ratios of the pericarp, pulp, and core. Creation of such a model and the above (1) to (4)
) It is the calculator 38 that executes the convergence calculation shown in the formula and calculates the sugar content of the fruit pulp.

FIG. 4 shows the results of applying the present invention to prince melon. The horizontal axis is the amount of attenuation of the pulp determined by this method, and the vertical axis is the value obtained by taking out the pulp after measurement and applying it to a refractometer. From this, it can be seen that the viscosity of fruit pulp can be estimated with an error of ±1.5 degrees.

〔Effect of the invention〕

According to the present invention, the viscosity of fruit can be measured quickly and non-destructively, so it can be used not only in fruit sorting plants but also in production.
Appropriate commercial transactions will be established in each process of distribution and retail.

[Brief explanation of drawings]

Figure 1 is a characteristic diagram showing the relationship between the sugar content of an aqueous solution and the amount of attenuation.
Fig. 2 is a cross-sectional view of a fruit-antenna showing the principle of the present invention, Fig. 3 is a block diagram showing an embodiment of the invention, and Fig. 4 is a characteristic diagram of experimental data showing the effects of the present invention. be. 32.33... Antenna, 34... Transmitter, 35.
36... Duplexer, 37... Receiver, 38... Computer.

Claims (1)

[Claims] The apparatus is equipped with a transmitting means for irradiating the fruit with microwaves, a receiving means for measuring the scattered waves scattered by the fruit, and a computer for analyzing the output of the receiving means, and a correlation between the attenuation coefficient and the sugar content of the fruit is provided. Using this fact, the amount of attenuation of the scattered waves is estimated from the assumed values of the attenuation coefficients of the pericarp, pulp, etc., corresponding to the size of the fruit, and this is compared with the received output to correct the attenuation function of the pulp. A sugar content measuring device characterized in that it is configured to estimate the sugar content of fruit pulp by repeating the process.