Date of Award
Doctor of Philosophy
S. Michael Kilbey, Vermont P. Dia, Tao Wu
The cuticle of all higher-plants is covered in lipidic layers of amorphous and crystalline waxes. The chemical composition and structure of cuticular waxes impart numerous functional properties to the surfaces of plants. Moreover, plant waxes are valuable industrial products with myriad applications; the postharvest coating of agricultural commodities for preservation serves as a salient example. There is an unfulfilled need in the agricultural sector for alternative wax materials to reduce reliance on imported waxes of botanical origin. Plant waxes are inherently complex mixtures composed of n-alkanes, as well as aliphatic alcohols, aldehydes, fatty acids, ketones, esters, and derivatives thereof. As such, it is difficult to ascertain the individual and synergistic functions of constituent entities.
The overarching objective of the present work was to elucidate whether the functionality of a bulk wax mixture could be traced to specific constituent entities. The systematic study of the individual and synergistic functions of plant wax constituents is necessary for the design of alternative wax materials for postharvest coatings.
The first chapter presents the purpose for undertaking this work, an overview of the chemistry, structure, and functionality of plant waxes, postharvest coating technologies, knowledge gaps, and objectives. The second chapter details the synthesis, chemical modification, and physical characterization of structural analogues of hydrogenated castor oil. The third chapter details the synthesis and physical characterization of 12 distinct plant wax constituents and a systematic investigation of their individual and synergistic functions. The fourth chapter details the synthesis and physical characterization of aliphatic aldehydes as well as an analysis on the implications for wax crystal growth. The fifth chapter details the chemical characterization of Cannabis sativa processing by-products, the study of which was originally undertaken in order to identify uses for a wax-like by-product of no commercial value. The last chapter presents a summary of key findings and introduces ideas for future work.
Leyva Gutierrez, Francisco Miguel Angel, "Chemistry and Functionality of Plant Waxes: Applications Toward Postharvest Coatings. " PhD diss., University of Tennessee, 2022.