Effects of common culinary cooking techniques on the antioxidants in collard greens

This thesis explores the effects of different cooking techniques on the antioxidant activity in collard greens. Chapter 1 is a literature review covering the topics of antioxidants, nutrition, cooking techniques and the effect of thermal treatment on antioxidants. Chapter 2 is a research manuscript evaluating collard greens from a local South Carolina farm exposed to seven different thermal treatments along with an untreated raw group. The thermal treatments utilized were saute, both long and short simmer, the saute treatment applied to both a long and short simmer treated group and the reserved cooking water from both a long and short simmer treatment group. After treatment, the total phenolic content (TPC) expressed in gallic acid equivalents/sample concentration (GAE/conc.) , 2,2-diphenyl-1-picrylhydrazyl (DPPH) and ferrous ion chelating (FIC) antioxidant assays were performed on all treatment groups. The saute treated group showed the highest TPC (8.2858 GAE/conc.) followed by the raw group (8.0361) and the short simmer + saute group (7.6227). The raw group showed the highest DPPH activity (7.7952 % inhibition/conc.) followed by the saute group (7.5877) and the short simmer + saute group (7.4753). In both of these assays the addition of a saute treatment to either short or long simmered treatment increased the antioxidant activity of samples compared to just the short or long simmer treatment alone. Additionally both TPC and DPPH assays showed greater antioxidant activity in the cooking water reserved from a long simmer treatment compared to the reserved cooking water of a short simmer treatment suggesting significant (p≤0.05) leeching of antioxidants from collard greens into the water related to the duration of aquathermal treatment. Similar trends were not found in the results of the FIC chelating assay where both long and short simmer treatment groups showed the highest chelating abilities and the reserved cooking water from both treatments showed the lowest chelating abilities. This suggests that chelators contained in collard greens are not water soluble and therefore not negatively affected by aquathermal treatments.