Date of Graduation
5-2025
Document Type
Dissertation
Degree Name
Doctor of Philosophy in Food Science (PhD)
Degree Level
Graduate
Department
Food Science
Advisor/Mentor
Wang, Ya-Jane
Committee Member
Lee, Sun-Ok
Second Committee Member
Mauromoustakos, Andronikos T.
Third Committee Member
Thallapuranam, Suresh
Fourth Committee Member
Savary, Brett
Keywords
Polyphenol; Protein; Rice; Sorghum; Starch
Abstract
Viscosity plays an important role in the food industry as it affects the quality, processing stability, and shelf-life of food and impacts physiological responses such as satiation and satiety. Greater viscosity reduces food intake by increasing the perception of satiety, primarily by delaying gastric emptying and increasing tactile stimulation. Starch is commonly added to food products as a viscosifying ingredient, which often involves chemically modifying the starch via cross-linking, to enhance its resistance to high shear, temperature and acidity. However, chemically modified starches are not “clean-label” ingredients due to the use of toxic chemicals. Therefore, further exploration is needed to develop starch-based ingredients that are solely comprised of natural and chemical-free components while preserving the functional characteristics of chemically modified starch. Recent research demonstrated that polyphenols enhance starch viscosity by interacting with proteins, highlighting their role as natural cross-linkers. Pigmented cereals are a good source of polyphenols, which interact with endosperm proteins to affect the pasting and rheological properties of starch. Nevertheless, the nature and extent of their interactions, as affected by polyphenol and protein classes, are unknown. The present study aimed to elucidate the nature and extent of polyphenol-protein interactions and their role in the viscosity development of rice and sorghum of varying bran colors. The covalent and non-covalent nature of polyphenol-protein interactions in pigmented and non-pigmented rice and sorghum and their effects on pasting properties, were studied using chemical agents and at different pH environments. The changes in molecular weight and size, and the secondary and tertiary structures of proteins, as affected by polyphenol class and concentration, were monitored via sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), high performance size-exclusion chromatography (HPSEC), circular dichroism spectroscopy (CD), and fluorescence spectroscopy, respectively. The viscosity development and protein structure were influenced by both polyphenol class and concentration. A low anthocyanin concentration in milled purple rice increased peak viscosity, and high anthocyanin levels in parboiled whole grain purple rice enhanced viscoelastic properties in an acidic environment due to the formation of covalent cross-links with glutelin. Black sorghum exhibited less breakdown in various pH environments as a result of hydrogen bonds and hydrophobic interactions between proanthocyanidins and prolamin. Polyphenol-protein interactions naturally enhanced and stabilized starch viscosity in both neutral and acidic environments, similar to chemically cross-linked starch, demonstrating their potential as clean-label ingredients with viscosifying and satiety-enhancing properties.
Citation
Jannasch, A. (2025). Polyphenol-Protein Interactions in Pigmented Cereals – a Clean-Label Approach to Tailor Starch Viscosity. Graduate Theses and Dissertations Retrieved from https://scholarworks.uark.edu/etd/5618
