The Study On Relationship Between Electrical Properties And Physiological Characteristics Of Kiwifruit And Peach

The variation rules of electrical properties and physiological characteristics of peach and kiwi were synchronously measured by using electronic instrument of Japan 3532-50 LCR and physiological and biochemical technology and the relationship between them compared. The general goals of this study were:1) to distinguish different species of kiwi (Hayward, Qinmei) and different species of peach (Qinwang, Qinguang No 2) by using electrical properties.2) to distinguish different maturity of'Hayward'kiwifruit by using electrical properties.3) to select sensitive electric parameters and characteristic frequency to distinguish the damage of the kiwi.4)to select sensitive electric parameters to quantize quality parameters of fruits.5) to accumulate the data on the change regularity of the kiwi electric properties and provide evidence for further exploiting the new and non-destructive inspecting instrument.The main research results were as follows:1. With the electronic instrument of LCR, the system analysis of the relationship among 14 electrical parameters of kiwifruit and peach was carried out. The electrical parameters include impedance (Z), static capacitance in series equivalent circuit mode (Cs), static capacitance in parallel equivalent circuit mode (Cp), inductance in series equivalent circuit mode (Ls), inductance in parallel equivalent circuit mode (Lp), admittance (Y), impedance phase angle (0), loss coefficient (D), reactance (X), Q factor (Q), effective resistance in series equivalent circuit mode (Rs), effective resistance in parallel equivalent circuit mode (Rp), conductance (G) and susceptance (B). The result showed that 14 electrical parameters is function of frequency;with the frequency shift, Z,θ,Cs,Cp,D,Rs,Rp and X change with cubic function curve; with the frequency shift, Y,Ls,Lp,G,B changes with power function. The same result on apple was found by Ma H J that 7(Z,θ,Cp,Lp,D,Rp,Rs) important parameters can feature the fruit electrical properties. It also provides a basis of electrical test parameters, simplifies the formalities and saves time and cost for the subsequent research.2. log10Z and log10f as well as log10Lp and log10f have a good linear relationship of fruits of kiwi and peach, R2 exceeded 0.95. Kiwi and peach can be distinguished by using value D within the 100Hz～1.58KHz frequency range under 24 electrical frequency. Kiwi and peach can be distinguished by using valueθand Rs within the 100Hz-6.31 KHz frequency range. Kiwi and peach can be distinguished by using value G within the 100Hz～100KHz frequency range. Within 15.8 KHz-100 KHz frequency range, kiwi(Hayward, Qinmei) and peach(Qinwang, Qinguang No 2) the four kinds of fruit can be distinguished by using value Z. Within 100Hz～158KHz frequency range, the four kinds of fruit can be distinguished by using value Cp.3. Under the condition of being stored at room temperature (25℃), the relationship of 4 fruit quality parameters (firmness, total soluble sugar, total acid, Moisture content) and 3 electrical parameters (Z, Cp, Lp) were studied. The results showed that the effective forecast model can be established and electricity parameter can mark nectarine fruit quality for correlation coefficients are significant among them. The feasibility of the model was verified by practice test. The study indicated that it was feasible to estimate the fruit quality by using electrical parameters, which was significant and useful in both practice and theory.4. The relationship of fruit 14 Physical parameters and 6 electrical parameters were studied when fruits were storied at room temperature (20℃). The results showed that the correlation between electric parameters (Lp, G and D) and physical parameters was low. So it can not use the 3 electrical parameters to mark the variation of physiological indexes. Z, Cp andθcan be used as sensitive electric parameters to symbolize physiological changes of the fruits in the characteristic frequency. The characteristic frequency of Z is 0.1 kHz and 2.51 MHz; the characteristic frequency of Cp is 1MHz and 1.58MHz; the characteristic frequency ofθis 0.1 kHz.5. The physical parameters of firmness and total acid (TA) of fruits of'Qinmei'kiwi were increased and total soluble sugar (TSS) was decreased with the extension of storage time at room temperature (20℃). It indicated that membrane integrity of cell became low for relative electrical conductivity of fruits increases. The ethylene production rate and respiration production rate changed as single peak and the peak time of ethylene production rate was in advance. The reducing of content of starch and cellulose was positively correlated with the declining of fruit firmness. It is can be inferred that amylase and PE play a main role first, then Cx and PG according to the activity peak time of softening relevant enzymes of kiwi.6. In this part,'Hayward'kiwifruit of appropriate harvest and late harvest was treated as the material to investigate the effects of 0.5μL/L of 1-methylcyclopropene (1-MCP) on post-harvest physiological biochemistry during room temperature (20℃). The results were:1) 1-MCP inhibited ethylene production speed and respiration intensity.2)1-MCP inhibited the lose of 'Hayward' kiwifruit firmness, titratable acids and vitamin c (Vc) content.3) 1-MCP increased the activity of the Peroxidase (POD), catalase (CAT) and Superoxide dismutase (SOD). In brief,1-MCP treatment delayed kiwifruit's ripening and softening. Compared with the degree of ripenessⅠ, kiwifruit of degree of ripenessⅡwas not suitable for preservation because the firmness falling was faster than the periodⅠ. Meanwhile, ethylene production rate was higher than periodⅠand the peak time was in advance. Z can distinguish different maturity of kiwi at characteristic frequency of 1MHz. Cp was an indicator to pick out different maturity of kiwi at characteristic frequency of 10 KHz.7. The kiwi falling from a height of 50 cm and 80cm onto a smoothly marble floor were used to investigate the effects of injury on such firmness, MDA, activities of lipoxygenase (LOX) of'Hayward' kiwifruits. The results showed that:1) the effect of mechanical damage on firmness was the biggest.2) the treatment was increasing ethylene production speed and respiration intensity.3) the process of aging and softening of fruits were faster due to the increase of O2- production rate, LOX and MDA. Meanwhile, damage treatment could cause the change of electric parameters but not affect the overall change trend. Damage treatment could cause the decrease of Z and the increase of Lp and D but it could not affect Cp,θand G in frequency of 100 KHz,251KHz,631KHz and 1MHz. Z can distinguish the wounded and the controlled fruits at characteristic frequency of 100KHz,251KHz,631KHz和1MHz. D can distinguish the wounded and the controlled fruits at characteristic frequency of 100KHz,251KHz.