This paper describes the development of a simple method to determine the permittivity and moisture content (m.c.) of
ginger. The measurement system consists of a microwave sensor, directional coupler and a PIC microcontroller. The
microwave sensor is a square flanged open-ended coaxial (OEC) sensor made from SMA stub contact panel with outer
diameter (O.D) 4.10 mm. The microwave oven drying method was used to determine the actual m.c. of the ginger. All data
acquisition, processing and display were accomplished using a PIC 16F690 microcontroller programmed using Flowcode
software. The actual values of the permittivity of ginger were obtained by using the Agilent (now Keysight Technologies)
85070B dielectric probe along with a HP 8720B Vector Network Analyzer (VNA). The results showed good relationships
between m.c., permittivity (dielectric constant (εʹ) and loss factor (ε̋)) and reflected voltage. The calibration equations
between reflected voltage and m.c. have been established for the sensor. The measurement system provides a simple, fast
and accurate technique to predict m.c., εʹ and ε̋ of ginger from reflected voltage measurements alone. The accuracy in
determination of m.c., εʹ and ε̋ in ginger was within 2.9%, 2.7%, and 3.6%, respectively.
The maturity of mango is usually assessed by the determination of its moisture content (m.c.), soluble solid content (SSC)
and pH. However, these techniques are either time consuming, tedious or destructive. In this research, we extend the
application of the open-ended coaxial probe technique to determine m.c. and pH of Chok Anan mango from its dielectric
properties from week 5 to week 17 after anthesis. The effects of frequency and m.c. on the values of the dielectric constant
and loss factor were also investigated. The critical frequency separating the different polarizations was found to be
inversely proportional to m.c. Also, in this research we proposed a new classification of fruit ripeness related to the number
of weeks after anthesis. The actual dielectric properties, m.c., SSC and pH of Chok Anan mango were measured using
standard methods. Relationships were established between the dielectric constant, loss factor, critical frequency, pH and
m.c. The accuracy for the determination of m.c. and pH using the coaxial probe was within 1.7% and 3.0%, respectively.