Date of Graduation

5-2015

Document Type

Dissertation

Degree Name

Doctor of Philosophy in Food Science (PhD)

Degree Level

Graduate

Department

Food Science

Advisor

Ya-Jane Wang

Committee Member

Dan Davis

Second Committee Member

Luke Howard

Third Committee Member

Andrew Proctor

Fourth Committee Member

Suresh Thallapuranam

Keywords

Acetylation, Isoamylase, Modified starch, Soluble complex, Starch, Starch-inclusion complex

Abstract

Starch-inclusion complexes have been proposed as delivery tools for bioactive molecules; however complexation yield is generally low with low solubility, which may limit the bioavailability of the included molecule. It was proposed that chemical (acetylation) and/or enzymatic (isoamylase and beta-amylase) modifications of starches prior to complex formation with fatty acids of different structures, including stearic, oleic and linoleic acid, may help increase complexation yield and solubility of the resulting starch complexes. Potato starch had a significantly higher complexation yield than common corn and high amylose (~70%) corn starches after debranching combined with a beta-amylase treatment. Debranched waxy maize starch and potato amylose displayed exothermic co-operative binding with hexanoic acid during the isothermal titration calorimetry (ITC) measurements. Acetylation improved the solubility of starch complexes and increased the amount of included fatty acids in both soluble and insoluble starch complexes compared with the unacetylated starches. The degree of acetylation was generally higher for the soluble complexes than for the insoluble ones, which also increased recovery of soluble complexes but decreased the recovery for the insoluble complexes. Complexation between acetylated starches and fatty acids decreased with an increase in degree of unsaturation following the order of stearic acid > oleic acid > linoleic acid. Acetylation of debranched starch alone or in combination with the beta-amylase treatment can be employed to increase complexation yield as well as to improve the solubility of complexes. This may potentially prove beneficial in food or pharmaceutical application because an increase in solubility can improve complex digestibility, and this may ultimately increase the bioavailability of the included molecules.

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