Annually, approximately 150 million metric tonnes of food goes to waste in the U.S., potentially causing economic loss and environmental pollution. Fermentation of food waste to produce acetone, butanol and ethanol (ABE) via fermentation has the potential to valorize food waste by producing value-added chemicals. However, the composition of food wastes from different sources vary, which affects ABE fermentation performance and hinders the commercialization of food waste fermentation. The objective of this study is to investigate the compositional variation of food waste collected weekly for 16 weeks (a total of sixteen samples) and determine how this variation affects ABE fermentation performance. Samples collected from Southgate Center, a food processing facility operated by Virginia Tech Dining Services, was characterized for use as a feedstock for ABE fermentation. Water, sugar, starch, fiber, protein, fat and ash concentrations in each of food waste samples were determined. ABE fermentation of these wastes was performed using Clostridium beijerinckii via batch fermentations. Correlations of ABE and butanol yields with the individual components of food waste composition were performed to better understand which components are key to ABE fermentation. Overall, this study demonstrated the feasibility of using food waste as a viable feedstock for ABE fermentation and investigated the effect of variation of food waste composition on the ABE fermentation performance. In the 16 collected samples, each major compositional attribute exhibited high variability. The concentration of total soluble sugar, defined as glucose, fructose, sucrose for the purposes of this experiment, ranged from 0.5 to 53.5% (dry basis) among different food waste samples. The concentration ranges of total starch, neutral detergent fiber (NDF), crude protein, crude fat and ash were 0 to 23.4% (dry basis), 0.6 to 25.8%, 5.5 to 21.2%, 0.1 to 37.9%, 1.4 to 13.7%, respectively. The high variation of food waste composition resulted in a high variation of ABE yield when these food wastes were subjected to fermentation by C. beijerinckii. The total ABE concentration following fermentation ranged between 6.9 to 17.0 g/L with an average value of 13.2 g/L. ABE and butanol concentrations are positively correlated with starch and equivalent glucose, i.e., the sum of initial free glucose and glucose that could be theoretically hydrolyzed from starch and sucrose during fermentation, but is negatively correlated with NDF concentrations. / Master of Science in Life Sciences / Nearly 40% of food in the U.S. goes to waste, causing a huge amount of economic loss and environmental pollution. Use of microorganisms to ferment food waste is a viable way to mitigate many of the issues associated with food waste. Put simply, fermentation is a biological process in which an organic substrate, such as food waste, is consumed and a more valuable product is produced. In this study, different food wastes were collected from the campus food processing center weekly for 16 weeks. Water, sugars, starch, fiber, protein, fat and ash contents of the collected food wastes were determined. Fermentation of these food wastes were conducted using a microorganism called Clostridium beijerinckii. The results showed that there was a high variation amongst the composition of the food waste samples. The concentration of total soluble sugar (glucose, fructose, sucrose) ranged from 0.5 to 53.5% (dry basis) among different food waste samples. The concentration ranges of total starch, neutral detergent fiber (NDF), crude protein, crude fat and ash were 0 to 23.4% (dry basis), 0.6 to 25.8%, 5.5 to 21.2%, 0.1 to 37.9%, 1.4 to 13.7%, respectively. The variation of food waste composition also led to different fermentation yields. It was also found that a higher glucose content in food waste results in a higher fermentation product yield; however, a higher fiber content in food waste results in a lower fermentation product yield.