Nondestructive detection of kiwifruit infected with Penicillium expansum based on electrical properties

Kiwifruit is extremely susceptible to spoilage by Penicillium expansum during postharvest storage, leading to decreased fruit market value. Therefore, rapid and efficient quality testing of kiwifruit is essential to maintain its good storage quality. Quality, biochemical parameters, and relevant electrical parameters were measured in the frequency range of 0.1–3980 kHz of kiwifruit which was divided into wound control and wound inoculation groups. Principal component analysis and correlation analysis further filtered the characteristic frequency and sensitive electrical parameters. The prediction models for non-destructive detection of kiwifruit blue mold were based on sensitive electrical parameters. The results showed that inoculation with P. expansum reduced the storage quality of kiwifruit and enhanced the activity of defense enzymes. The characteristic frequencies of the wound control group and the wound inoculation group were 3980 kHz and 0.1 kHz, respectively. Electric conductivity σ can be used as a commonly used sensitive electrical parameter. The prediction model was established based on firmness and σ was highly accurate, the residual values were all between − 2 and 2, and the verification experiments showed that the correct recognition rate was 82%, which provided a basis for non-destructive monitoring and accurate diagnosis of kiwifruit infected with P. expansum.