Date of Graduation


Document Type


Degree Type



Davis College of Agriculture, Natural Resources and Design


Human Nutrion and Foods

Committee Chair

Kristen E Matak


Electron beam (e-beam) irradiation is an effective non-thermal processing step for the reduction of Salmonella in peanut butter. The objective of this study was to evaluate the effects of e-beam irradiation on the quality of peanut butter. Peanut butter samples were exposed to e-beam doses of 0 (control), 3.2, 7.0, or 27.7 kGy, confirmed by film dosimetry. Doses correlated with a 5- and 12-log reduction of Salmonella respectively; with 27.7 kGy representing an extreme dose. Samples were examined over a 15-day period at 22°C. Color analysis (L, a*, b*), spreadability, and thiobarbituric acid reactive substances test (TBARS) for lipid oxidation were measured over a two-week storage period. Fatty acid profiles were measured on days 3 and 15 and amino acid profile was measured on day-15. Protein degradation was measured on day-15 by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-Page). TBARS showed an increase in malondialdehyde (MDA) formation with e-beam dose (P0.05). No changes in total saturated fatty acid content, total unsaturated fatty acid content, total monounsaturated fatty acid content, or total polyunsaturated fatty acid content were observed by dose or over time (P >0.05). No changes in crude or total protein were observed; however decreases in serine, tyrosine, histidine, and arginine were observed with dose ( P<0.05). SDS-PAGE showed decreases in band pixel density at 27.7 kGy, indicating degradation of proteins (P0.05). Significant changes in color ( P<0.05) were observed as e-beam dose increased. These results demonstrate e-beam irradiation when applied to peanut butter to produce significant changes in color and protein degradation. No changes were observed in total protein content, or total saturated and unsaturated fatty acid content. Future studies may include sensory evaluation and consumer acceptance studies.