Study On Dielectric Properties Of Persimmon Fruit And Influence Of 1-MCP On Physiological Characteristic Of Persimmon Fruit

Dielectric properties of postharvest persimmon fruit are studied by using a HIOKI 3532-50 LCR tester. Dielectric parameters mainly include dielectric constant, loss facto, conductance, inductance in parallel equivalent circuit mode impedance, impedance, real part and false part of impedance. The research focuses on an investigation of the relationship between dielectric properties and mature character, with a purpose to make a further inquiry into feasibility non-destructive test for persimmon fruit based on dielectric properties. Besides, a subsequent study on physiological and biochemical characteristics of persimmon fruit is also made, in the interest of learning feasibility of 1-MCP treatment for keeping deastringent persimmon treated with CO2. The results of which will bring some implications to the improvement of preservation technology of persimmon fruit.The results are as follows:(1) Both impedance and inductance in parallel equivalent circuit mode of persimmon fruit shows an obvious decrease with increasing frequency, and conductivity of persimmon fruit a clear increase. Both dielectric constant and loss factor assume change tendency in the peak within the frequency range.(2) Research findings show that dielectric properties change is significantly correlated with maturation. Both impedance and inductance in parallel equivalent circuit mode of persimmon fruit tend to decrease with a longer shelf life at room temperature at a constant frequency, while conductivity, dielectric constant and loss factor tend to increase. 1MHz is the characteristic frequency of persimmon fruit where constant of senile persimmon fruit is 3.5 times more than that of fresh one.(3) Changes of dielectric parameter aroused by variety of frequency reflect the response feature of persimmon fruit to electric field frequency. This is fundamental to fruit test using dielectric properties. Compared with former research, all of impedance, inductance in parallel equivalent circuit mode and conductance were newly introduced parameters in this study. More comprehensive dielectric studies on fruit are conducted, which enrich the theoretical bases in the dielectric nondestructive test.(4) 1-MCP treatment probably can restrain the decline of firmness of deastringent persimmon fruit at room temperature, and reduce rate of soften fruit. Crispness-keeping effect of 1-MCP treatment on deastringent persimmon fruit indicates very effective results, thus will likely bring about a nice application prospect.(5) 1-MCP treatment tends to postpone the appearance of respiration and ethylene production peak, and reduce areas of respiration and ethylene production peak.(6) 1-MCP treatment appears to depress the strengthening in the activity of LOX and the increase in content of MDA, and to control breakage of membrane attribute to lipid peroxidation; 1-MCP treatment can also depress the activity of PPO and alleviated brown efficient.(7) 1-MCP treatment combining with CO2 treatment is a good way for deastringency and firmness. This method is propitious to store and commodity of persimmon fruit.