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The pinto bean has been linked to the prevention of multiple diseases due in large part to the presence of phenolic antioxidants, which are higher in beans than in many fruits and vegetables. These components deliver health properties beyond basic nutritional characteristics by scavenging free oxygen radicals. However, these benefits are most likely due to the ability of these chemically diverse phenols to impart greater protective properties as additives or synergists acting in combination. However, optimal parameters to isolate these compounds (in terms of ratios and types) from a given natural source are not known. Without this knowledge, understanding the responsible components and their possible synergistic / additive / potentiate mechanistic interactions is problematic at best.
Therefore, the objective of this project, which is a step toward achieving the long-term goal, was to apply response surface techniques to obtain pinto bean extracts with high total phenols (TP) flavonoids (TF) and antioxidative capacities (AC). This project was completed by using a three factor face centered composite - response surface design that consisted of adjusting the solvent polarity ratio (organic vs water) of six different solvents (methanol, methanol – HCl, ethanol, ethanol – HCL, acetone, acetone – HCl), while also modifying for mix time and solid / solvent ratio. The most effective factors relative to maximum TF and TP yields were a solvent composition of 50% and solid ratio of 10% and a 60 min mix time, although the solvents were different. 50% Acetone: water without HCL was the most effective for extracting TP, while 50% methanol:water without HCl yielded the highest TPs and AC values. Other solvents produced even higher values, but the data did not fit the models, which could be due to variability in the assays or pinto bean particle size, or that a higher order model is needed. Still, the data suggest that HCl is not needed for these extractions, as it did not aid and often resulted in lower AC and phenolic values. Furthermore, compositional analysis of select samples shows that slight changes in the processing parameters, as well as the solvent used, resulted in different profiles.
Advisor: Vicki Schlegel