IMPROVING CALCIUM PENETRATION: MEASUREMENT AND FACTORS AFFECTING CUTICULAR PENETRATION

We developed a finite-dose diffusion system using a Ca²⁺ ion-selective electrode for evaluating factors affecting cuticular penetration.
Ca²⁺ penetration was followed using cuticular membranes (CM), enzymatically isolated from mature tomato fruit, with a finite-dose diffusion half-cell as a model system.
A Ca²⁺ ion-selective electrode was used for the determination of Ca²⁺ concentration in the receiving solution (20 mM KCl). Single droplets (1μl) of CaCl₂ solution were applied on the cuticular surface as a source of Ca²⁺. The response of the Ca²⁺ ion-selective electrode was rapid, and the response time to reach a constant value was usually 2–5 minutes.
The electrode gave a Nernstian (linear) response for calibration solutions in the range of 10^-2 to 10^-4 M Ca²⁺. Sensitivity for Ca²⁺ was in the range of 1 to 5 x 10^-6 M Ca²⁺. The electrode was fully functional for at least 3 weeks.
Transcuticular penetration of Ca²⁺ following application of 2 to 6 μl droplets of CaCl₂ at 0.05–1.0 M was readily detectable.
Steady-state flow was observed for at least 60 h.
About 0.80±0.65 % (n=13) of the applied Ca²⁺ penetrated within 19 h.

II Workshop on Pome Fruit

T. Ohkouchi, Martin J. Bukovac, G. Noga

tomato fruit cuticles, Ca²⁺ ion-selective electrode

https://doi.org/10.17660/ActaHortic.1998.466.19