Tristearin as a model cuticle for high-throughput screening of agricultural adjuvant systems

The widely varied compositions and structures of plant cuticles create problems in the identification of suitable model systems for laboratory testing of adjuvants. We have compared the behavior of an extracted cuticle wax with tristearin, a well characterized crystalline triglyceride, which we propose as a model cuticle for ranking new adjuvant systems for their propensity to disrupt the cuticle barrier. The interaction of adjuvant products and their components with the extracted cuticle wax and tristearin was determined using differential scanning calorimetry and small angle X-ray scattering approaches. The interaction of the additive with tristearin caused a concentration-dependent change in the crystallite level, and correlated between the extracted wax and tristearin. Tristearin was subsequently used to compare the effectiveness of a range of adjuvant products and their major components. This approach has utility to quantify the effects of adjuvant components and enable more judicious selection of adjuvant candidates to progress to plant trials.