• A multifrequency dielectric analysis (10–1000 kHz) was conducted to optimize electrostatic separation of saffron stigma and style. • Maximum dielectric contrast (156%) was achieved at 40°C and 10% moisture content, enhancing separation efficiency. • Moisture content had the strongest influence on dielectric properties, particularly in style tissues. • Dielectric constant (ε') increased with temperature and moisture, but decreased with rising frequency. • Statistically significant interactions among temperature, moisture, and frequency confirm the need for multidimensional optimization. Traditional separation of saffron stigma-style differentiation has historically exploited disparities in dielectric constants such as relative permittivity (ε'). This study investigates the conditions under which the dielectric properties of saffron stigma and style diverge most significantly, demonstrating that optimized combinations of temperature and moisture can substantially enhance the contrast between these two tissues. The study employed a systematic investigation of thermal and hygroscopic parametric influences on electrostatic responses to identify optimal separation. The multifrequency analysis (10, 100, and 1000 kHz) revealed maximal permittivity contrast at approximately 40°C and 10% moisture content, with the style exhibiting consistently elevated ε' relative to the stigma. Multifactorial ANOVA confirmed that temperature, moisture content and frequency each had a statistically significant effect on dielectric properties (P < 0.05), with moisture content showing the greatest influence particularly in style tissue. Significant interaction effects further indicate synergistic relationships among the parameters. Quantification of parametric dependencies revealed a positive correlation of ε' with temperature and moisture content but exhibited an inverse relationship with excitation frequency. The observed 156% dielectric constant deviation under optimized conditions (40°C and 10% moisture content) resolves prior limitations attributed to analogous dielectric profiles, enabling improved electrostatic separation. These findings also advance industrial applications, including dielectric spectroscopy protocols and energy-efficient drying processes of saffron, by leveraging precise environmental conditions modulation into saffron processing workflow.
Mazloumzadeh et al. (Sun,) studied this question.