Macronutrient-flavonoid interactions, effects in model food matrices
Macronutrient-flavonoid interactions have been well documented through the years. Chapter 1 of this document provides an introduction of the literature documenting the theoretical and mechanical framework of their importance in human health, biological interactions, macronutrient interaction, and general bioaccessibility and bioavailability. Though macronutrient interactions have been characterized, often the levels utilized are above those that may be seen in processed food products due to undesirable effects. This document covers the effects two commonly used plant extracts, green tea extract and grape seed, may have on the macronutrient functionality in model food matrices. In Chapter 2 the effects of crude extracts (green tea and grape seed) and a purified green tea extract (composed primarily of EGCG) were examined for their effects on various protein functions within a gel, emulsion, and foam matrix. Due to their occurrence in many packaged food products the dairy proteins, sodium caseinate and whey protein isolate were utilized. These extracts were incorporated into each of the above stated matrices at levels that may be plausible in consumer packaged food products with minimal effects on the sensorial properties. It was determined that though level of incorporation were modest, an impact may still be had on the functional properties of these matrices. The addition of grape seed and green tea extracts may moderately alter gelation properties, including gel strength and gelation time. Likewise, emulsion stability was negatively modified while foam stability exhibited an inverse alteration. Similar functional testing of functionality in carbohydrates were reviewed in Chapter 3, using wheat starch and κ-carrageenan, both commonly found in processed foods, representing a digestible and non-digestible carbohydrate, respectively. The crude green tea and grape seed sourced extracts were incorporated into the carbohydrate systems to determine the effects on starch pasting and polysaccharide gelation using dynamic rheology. In wheat starch pastes the incorporation of the plant extracts exhibited a dose dependent response that resulted in a decrease in gelatinization temperature and time however offered minimal overall impact on the final viscosity. Similarly the impact on the gelation of κ-carrageenan in the presence of green tea or grape seed extract was minimal in regards to its flow properties. Chapter 4 evaluated how the bioaccessibility of flavan-3-ols from the plant extracts were impacted by their incorporation into the protein and/or carbohydrate matrices. Each of the crude green tea and grape seed extracts, along with the purified EGCG green tea extract were combined in the aforementioned food matrices and digested using a three stage static in vitro digestion model to determine the effects on bioaccessibility. These studies indicated that carbohydrate and protein matrices modulate the bioaccessibility of flavan-3-ols. Both types and structures of the macronutrients resulted in a modulated effect of overall relative bioaccessibility. The composition of the extract may have a modulating effect on bioaccessibility of the individual flavan-3-ols present. Chapter 5 reviewed the results of these studies to offer final overall conclusions and potential next steps for further research.
Ferruzzi, Purdue University.
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