CN101551353A

CN101551353A - Method for checking celery quality change without loss by using dielectric property

Info

Publication number: CN101551353A
Application number: CNA2008100446483A
Authority: CN
Inventors: 秦文; 辛松林
Original assignee: Individual
Current assignee: Individual
Priority date: 2008-06-06
Filing date: 2008-06-06
Publication date: 2009-10-07

Abstract

The invention relates to a method for checking celery quality change without loss by using dielectric property, which is an invention in the field of the quality check of agricultural products. The new method relates to the relevant contents of the fields of electrics, physics and agricultural product storage and preservation and is based on the crossed subjects. The original identification on the quality of the agricultural products such as celery, and the like is realized by the qualitative judgment of people sense organs or the quantitative judgment of experimental instruments or reagents, the former has higher subjectivity and haphazardry, and the latter is more accurate and has complexity and labor and time consumption. The method is between the qualitative judgment and the quantitative judgment, judges the quality change by using the fluctuant change of the self dielectric parameter in the celery storage process and can rapidly check the internal quality (freshness) of the celery without loss and can be used for judging the freshness grade of the celery.

Description

A kind of method of utilizing the dielectric property checking celery quality to change

Technical field

The invention belongs to the agricultural product quality detection range, particularly lossless detection method and device can be applied to preserve and the on-line monitoring of field of circulation celery quality.

Background technology

Along with improving constantly of people's living standard, the consumption figure of quality vegetables is increased day by day.Celery is the generally edible a kind of vegetables of China, not only contains nutritional labelings such as rich in protein, vitamin, mineral element, and contains special step-down, reducing blood lipid, anticancer isoreactivity material, is considered to important natural health care.But it is adopted the back freshness and descends soon, and quality changes greatly, often shows surperficial shrinkage and here withers, takes off phenomenons such as greenish-yellowization, gloss go down, tissue wears out.Monitoring to its quality mainly relies on sensory evaluation and chemical method, when adopting the sensory testing, often contain subjective factor, this has just influenced the correct evaluation to the celery quality undoubtedly, conventional physico-chemical method sampling operation complexity, analytical test time are long, robotization, intelligent degree are not high, are difficult to realize quantification and extensive continuous detecting.Seek a kind of simple, fast, harmless detection method is to the preservation and freshness of celery and cargo carrier is significant and promotional value.

At present, the research of dielectric property is a research focus in physical properties of food field, is applied to the product quality analysis in food scientific research, for the Non-Destructive Testing of fresh vegetables quality provides a new way.Dielectric property is used for agricultural product quality detects only cereal crops moisture determinations such as pair cereal in the existing literature data record, and utilize dielectric property to detect the report of the fruit fresh material degree of regular shape, but for the research report of the basic electrical characteristics of greengrocery material and quality Dynamic Non-Destruction Measurement seldom, particularly the material that has stem, out-of-shape, size to be difficult to determine again of the existing leaf as the celery does not appear in the newspapers especially.The present invention does not at home and abroad appear in the newspapers.

Summary of the invention

In order to realize that quick nondestructive detects the celery quality, the present invention utilizes in the self-control plane-parallel capacitor monitoring celery postharvest storage process response condition to extra electric field, this device is characterised in that: comprise that a signal receives and process instrumentation (dielectric parameter surveying instrument, LCR-3532, HIOKI), signal output and pen recorder (computing machine), measurement mechanism (plane-parallel capacitor that has radome) and connecting line etc.Radome in the measurement mechanism is made by the net metal silk, two 15cm * 15cm that plane-parallel capacitor adopts, and the thick corrosion resistant plate of 0.1cm can be adjusted spacing as the two poles of the earth by cross-over block between two-plate.

Plant tissue can be similar to regards two phase composition systems as: one is the iuntercellular tissue that is made of cell membrane, cell membrane mutually, and it has significantly semiconductor property and dielectric property, has bigger resistance.Another is intracellular fluid and extracellular fluid mutually, and they contain multiple conductive ion and have ionic conductivity, and resistance is less, and its electric rerum natura and water percentage have significantly correlationship.Cell membrane, the cell membrane of fresh and alive plant material are thicker, and ion permeability is poor, and resistance is very big, electric capacity is less.When cytoactive reduces, cause cell membrane, cell membrane dissolving, attenuation on the one hand, its ion permeability is increased, electric capacity increases, and resistance reduces.Simultaneously, the increase of conductive ion moving resistance raises its resistance in the cell liquid because the minimizing of cell moisture causes again.These two kinds of processes affect the conductive capability of plant jointly.Electric capacity increases when the former influences greater than the latter, otherwise then electric capacity descends.Therefore, utilize the variation of the change reflection quality of vegetable of dielectric parameter to have feasibility in the vegetable storage process.

The quality of agricultural product such as celery was differentiated it is by the qualitative judgement of people's sense organ or the quantitative judgement of instrument or reagent by experiment, the former subjectivity and randomness are bigger in the past; The latter is comparatively accurate, but comparatively complicated, wastes time and energy.This invention is between qualitative and quantitative is judged, utilize in the celery storage undulatory property of self dielectric parameter to change the variation of judging its quality, can realize that quick nondestructive detects the inside quality (freshness) of celery, and be used to judge the celery grade of freshness.

The dielectric property measurement result is except outside the Pass having with the experimental subjects celery, and the humiture of voltage, two-plate spacing and air has certain relation also and between the plate when measuring.Obtain following result in the preliminary experiment process of carrying out the quick nondestructive detection: dielectric parameter is along with the spacing of two-plate changes the variation that presents undulatory property, and in distance between plates was the 1cm-7cm scope, along with the increase of distance between plates, impedance and inductance increased, and electric capacity reduces; Under the constant substantially situation of humidity, along with the rising of temperature, impedance and inductance reduce, and electric capacity increases.Therefore, in carrying out the Non-Destructive Testing process that the celery quality changes, we choose voltage between fixing distance between plates and plate, and change under the little environment in the temperature difference and humidity and to measure.

Description of drawings

Fig. 1 pick-up unit synoptic diagram

Fig. 2 battery lead plate synoptic diagram

Fig. 3 control circuit synoptic diagram

Embodiment

1. the grouping of sample

The celery sample is divided into three groups at random, place the variation of measuring dielectric parameter between the plane-parallel capacitor with first group, physical and chemical index of second group of per 6 hours mensuration, comprise indexs such as color, weight-loss ratio, respiratory intensity, ascorbic acid content, activity of catalase and hardness, the 3rd group is control group, and does repeated experiments.

2. the measurement of dielectric property

First group of celery sample placed between two parallel plate electrodes, and the statistical study of in 1V～5V scope voltage fluctuation being measured as a result determines that 3V is best mensuration voltage.In 100Hz～5MHz scope, choose 17 frequencies and measure,, determined the frequency of 100kHz for measuring by the calculating of measured value mean deviation, standard deviation and the coefficient of variation under the different frequency.Choose the F=100kHz frequency celery dielectric property in the storage is carried out METHOD FOR CONTINUOUS DETERMINATION.Numerical fluctuations every 6 hour record measuring process middle impedances and electric capacity changes.

3. the mensuration of physical and chemical index

At the celery duration of storage, celery color, weight-loss ratio, respiratory intensity, ascorbic acid content, activity of catalase and hardness measured in per 6 hours, measure altogether 8 times.All physical and chemical indexs are all measured 3 times, average.

4. opening relationships function

Respectively that the impedance in 48 hours is corresponding with every physical and chemical index with electric capacity, carry out correlation analysis.

By correlation analysis as can be seen, the correlativity of electric capacity and weight-loss ratio is best, and the coefficient of determination is 0.9488, therefore, can utilize the method for the relation function of electric capacity and weight-loss ratio that the celery quality is carried out on-line monitoring.

Claims

1. method of utilizing the dielectric property checking celery quality to change, it may further comprise the steps:

(1) utilize the stainless steel metal plate to be made into plane-parallel capacitor, the quality of the sample that is placed in one in order to monitoring changes.

(2) in frequency condition is 100Hz～5MHz scope, voltage conditions is to measure under the experiment condition in 1V～5V scope interval.

(3) celery is carried out the detection of physical and chemical index, detect index and comprise color, weight-loss ratio, respiratory intensity, ascorbic acid content, activity of catalase and hardness, the measurement result of result and dielectric parameter is analyzed, obtained having best correlativity between weight-loss ratio and the capacitance.

2. according to the described measurement mechanism of claim 1, be the capacitor that two parallel steel plates are formed, be lined with cross-over block between parallel-plate, the capacitor outside is covered with the tinsel gauze screen, is connected to ground wire on the gauze screen.

3. according to the described measuring condition of claim 1, segmentation is chosen 17 Frequency points and is measured in 100Hz～5MHz scope, by the calculating of measured value mean deviation, standard deviation and the coefficient of variation under the different frequency, has determined the frequency of 100kHz for measuring.The statistical study of in 1V～5V scope voltage fluctuation being measured as a result determines that 3V is best mensuration voltage.

4. according to claim 1 is described being measured as of celery physical and chemical index measured once in per 6 hours, set up the related function of electric capacity and weight-loss ratio.