Dielectric spectrum of ripe papaya and navel orange fruit juices from 1 to 50 GHz using time domain reflectometry

This paper investigates the complex dielectric properties, consisting of the real part, i.e., dielectric constant (ε') and the imaginary part, i.e., dielectric loss (ε''), of ripe papaya and navel orange fruit juices utilise the time domain reflectometry (TDR) technique. Filling a significant gap in existing literature, the study focuses on fruit juice complex dielectric properties measurement within the frequency (f) range 1GHz ≤ f ≤ 50 GHz to know the frequency dependence variation. Experimental measurements were conducted at 23 °C using fruit samples processed into filtered juices. The ε'-f curves reveal distinct dielectric behaviours between papaya and orange juices. Papaya exhibited significantly higher ε' up to 18 GHz, but this trend reversed thereafter. Similar opposing behaviors were observed in the ε''-f curves. Both juices displayed relaxation frequencies, with papaya peaking at 8 GHz and orange at 10.5 GHz. The study has the potential to advance food processing procedures, boost product standards and stimulate innovation across several sectors.