Biological Analysis of Prebiotics in Various Processed Food Matrices

The addition of prebiotic to a variety of food products has become a more common occurrence in recent years. Although research on the stability of prebiotics has been conducted, knowledge of the stability of prebiotics in processed foods is limited. The purpose of this research was to determine the biological stability of five prebiotics in a variety of food matrices when processed under various conditions. A biological test, the prebiotic activity assay, was used to test for stability of six food products (muffin, cookie, granola bar, breakfast cereal, sports drink, and bread) containing five different prebiotics (fructooligosaccharides (FOS), inulin, galactooligosaccharides (GOS), resistant starch, and polydextrose). The prebiotic activity assay reflects the capability of a prebiotic to support the growth of a probiotic strain relative to an enteric strain and relative to growth of both on a non-prebiotic substrate. Due to the complex matrices of the food products as well as low concentrations of prebiotics, the prebiotic activity assay was not sufficiently sensitive to assess biological stability in these food products. Additional food products (cracker, granola, and sports drink) were produced without background sugars and included a higher concentration of prebiotic, 10%. The prebiotic activity assay was used to assess the biological stability of prebiotics within these food matrices. Overall, FOS and inulin were stable when exposed to mild to moderate heating, but were biologically degraded when exposed to an acidic environment and moderate heat. GOS was stable when exposed to mild to moderate heat as well as when exposed to an acidic environment that was processed with moderate heat. Resistant starch posed problems with being accurately tested for prebiotic stability, and no strong conclusions were able to be made based on the results obtained through this method. The prebiotic activity assay was able to assess the biological stability of prebiotics in food matrices when exposed to several processing conditions, although the assay was better suited for certain prebiotics as well as certain food matrices. iii Acknowledgements I would like to express my sincerest gratitude to those who helped guide, support and encourage me throughout my research and studies as well as those who made this research possible. I would like to acknowledge the United States Department of Agriculture for providing the grant funding this research. I would like to thank Dr. Marx for his help in providing statistical analysis for this data. Thank you to Michelle Hoffman and Emily Ang …