Wang, Lei2017-03-142017-03-142016-12https://hdl.handle.net/11299/185115University of Minnesota Ph.D. dissertation. December 2016. Major: Nutrition. Advisor: Chi Chen. 1 computer file (PDF); ix, 196 pages.Temperature is a fundamental parameter in nature that determines the physical properties of materials, the rate and extent of chemical reactions, and the scale and direction of thermal radiation. Energy associated with high temperature can affect the survival and wellbeing of a living organism, directly through heat stress, and indirectly through exposure and consumption of thermally-processed food and chemicals. In this project, the direct influences of thermal energy on a biological system were examined by the metabolomic analysis of heat stress (HS)-elicited metabolic effects in pigs, while the indirect influences of thermal energy on a biological system were investigated by the chemometric analysis of heating-induced chemical changes in frying oils and the metabolomic analysis of metabolic changes induced by the consumption of thermally-oxidized cooking oils in mice. The results of these metabolomics and chemometric analyses are summarized as follows: (1) HS greatly affected diverse metabolites associated with amino acid, lipid, and microbial metabolism, including urea cycle metabolites, essential amino acids, phospholipids, medium‐chain dicarboxylic acids, fatty acid amides, and secondary bile acids. More importantly, many changes in these metabolite markers were correlated with both acute and adaptive responses to heat stress. (2) Thermal stress-elicited degradation of triacylglycerols and formation of lipid oxidation products (LOPs) in vegetable oils occurred simultaneously at frying temperature. Specific aldehydes and aldehyde clusters could be more effective indicators of lipid oxidation status for frying oils and fried foods than many traditional markers. (3) Feeding heated soybean oil (HSO) significantly altered the composition of the metabolome by introducing diverse LOPs and altering the metabolism of lipids, amino acids, and antioxidants. Among these metabolic changes, the decrease of serum tryptophan and the increase of urinary tryptophan metabolites were caused by HSO-elicited activation of tryptophan-NAD+ catabolic pathway. Overall, these results from metabolomic and chemometric analyses provide mechanistic insights on thermal energy-induced chemical and metabolic events.enThesis or Dissertation