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Enzymatic and chemical syntheses and purification of sucrose fatty acid esters
Abstract
Sucrose fatty acid esters are surfactants that are a combination of sucrose, a water-soluble compound, with a non-polar fat. Their unique properties provide for a wide range of applications in foods, pharmaceuticals, cosmetics and detergents, to name a few. This study investigates new approaches in synthetic methods, both chemical and enzymatic, as well as novel purification and chromatographic studies. Lipase-catalyzed transesterifications between triglycerides in vegetable oils and sugars were explored. Experiments which vary sugars, lipases, vegetable oils, emulsifiers, temperature and water content are reported. The solubility of the sugars in oil and their stereochemistry were important factors in the success of these experiments. High-performance liquid chromatography (HPLC) and thin-layer chromatography (TLC) methods are described for separating sucrose monostearate isomers. The HPLC procedure provides baseline separation of purified monoester isomers into three main peaks at room temperature, and completely separates monoesters with different acyl chain lengths (C$\sb{14}$, C$\sb{16}$, C$\sb{18}$). The TLC method separates up to six of the eight possible positional monostearate isomers, which can be further differentiated by specific color development with a visualizing agent. Isomers collected from HPLC were subjected to treatment with invertase, then resolved and detected by TLC to determine fatty acid substitution patterns on the sucrose molecule. A method is described for the conversion of sucrose esters exhibiting a high degree of acylation to sucrose esters which are mono or disubstituted. This is accomplished by chemically catalyzed transfer of acyl functions from a highly acylated sucrose ester molecule to the hydroxyl groups of free sucrose. This chemical transesterification system was studied under various reaction conditions to find the optimal conditions for the highest yield of sucrose monoester production. A purification system is described which utilizes a two-solvent system, ethanol-water, to precipitate the sucrose esters in the initial step of purification, directly from the reaction solvent. This method removes the sucrose and other unreacted starting materials, color and odor resulting from decomposed starting reactants. This purification system does not require prior distillation of the reaction solvent, pH adjustment or the addition of acids or salts. A high quality sucrose ester product relatively free of reaction solvent is the result.
Subject Area
Organic chemistry
Recommended Citation
Dean, Maria A, "Enzymatic and chemical syntheses and purification of sucrose fatty acid esters" (1991). ETD collection for University of Nebraska-Lincoln. AAI9208104.
https://digitalcommons.unl.edu/dissertations/AAI9208104