Relationship between Postharvest Physiology, Quality and Electrical Properties of Kiwifruit Infected with Penicillium expansum

In order to improve the way of nondestructive detection of kiwifruit and provide a new method to investigate whether the kiwifruits is infected with Penicillium expansum (P. expansum), the quality, physiological indicators and the relevant electrical parameters within the frequency range of 100 Hz~3.98 MHz of Hongyang kiwifruit which were infected with 15 μL 1×106 CFU/mL P. expansum spore suspension in the storage period were measured, while the control group was infected with sterile water. The characteristic frequency and sensitive electrical parameters were screened out through principal component analysis and correlation analysis, and the mathematical models were further established. The results showed that the characteristic frequency of control group treated with sterile water and the inoculated group treated with P. expansum was 3 956.5 kHz and 251 Hz, respectively, the sensitive electrical parameters were equivalent series resistance Rs and equivalent series capacitance Cs, respectively. As for the control group, β-1, 3-glucanase (GLU) activity was highly correlated with Rs, and as for inoculated group, the titratable acid TA content was significantly correlated with Cs (P< 0.01). The mathematical regression equations were also established, which indicated that the electrical parameters can better reflect the quality of kiwifruit. As long as the measurement of electrical parameters, the value of GLU activity or TA content can be calculated to determine whether the kiwifruit was infected with P. expansum. The study provided a theoretical basis for the nondestructive detection of kiwifruit penicilliosis. © 2021, Chinese Society of Agricultural Machinery. All right reserved.