<div>Shifts
in the human diet to more refined foods and ingredients have contributed to the
rise in metabolic disease rates associated with long-term consumption of foods
causing swift rises in blood glucose response. Foods which result in a more
moderate blood glucose curve are considered healthier by increasing satiety and
reducing oxidative stress. Sorghum products contain naturally slowly digested
starch. The matrix of sorghum porridges contains kafirin protein bodies which
cross link around gelatinizing starch molecules, while similar nascent matrices
in other cereals aggregate and collapse. The 3-deoxyanthocyanidin pigments
unique to sorghum may be accountable for the difference in matrix stability.
The density of the starch entrapped in the matrices is thought to partially
inhibit α-amylase access to the starch, reducing overall starch digestion and
thereby mitigating glucose response. The purpose of this work was to increase our
understanding of how phenolic compounds in sorghum interact with endosperm
proteins to create a stable matrix, and to explore if the knowledge might be
translated to other starchy cereal products. In the first study, phenolic
extracts from flours (sorghum, corn masa, white rice) were characterized for
phenolic content, antioxidant activity, phenolic components, and their ability
to interact with a model protein system (ovalbumin) in order to examine protein
polymerization. In the second study, specific
phenolic compounds in sorghums (<i>p</i>-coumaric,
sinapic, and gallic acids; (+)-catechin; and apigeninidin, a
3-deoxyanthocyanidin found in sorghums) were interacted in the model protein
system at different concentrations to observe extent and type of protein
polymerization, and promising compounds subjected to fluorescence quenching
spectroscopy to examine the nature of the interactions. The final study explored the effects of apigeninidin addition to a
yellow corn flour and naturally present anthocyanin (blue corn) on starch
digestion and microstructure of porridges by utilizing an <i>in vitro</i> α-amylase assay and confocal microscopy. </div><div>The slow digestion of starch in cooked sorghum products
can be attributed to the 3-deoxyanthocyanidin compounds present in the grain
participating in sulfhydryl-disulfide interchanges which results in extensive
kafirin cross-linking surrounding starch granules. While other phenolic and
redox-active components may affect matrix formation and stability,
3-deoxyanthocyanidins appear to have the most direct influence, and their
ability to modify food protein matrices appears to have a direct result on
starch digestion <i>in vitro</i>.</div>
| Identifer | oai:union.ndltd.org:purdue.edu/oai:figshare.com:article/8312204 |
| Date | 15 August 2019 |
| Creators | Leigh C R. Schmidt (6869153) |
| Source Sets | Purdue University |
| Detected Language | English |
| Type | Text, Thesis |
| Rights | CC BY 4.0 |
| Relation | https://figshare.com/articles/Investigating_Phenolic-Mediated_Protein_Matrix_Development_for_Potential_Control_of_Cereal_Starch_Digestion/8312204 |
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