Sensory Odor Evaluation of Trap Grease and Trap Grease Biodiesel

Waste oils and greases from commercial restaurants, also known as trap grease, are potential feedstocks for sustainable biodiesel production. A significant challenge in producing biodiesel from trap grease is the very strong and offensive odor it can possess. The odor can be attributed to several factors including the volatile chemical compounds created during fermentation and biodegradation of oils and fats. Sensory assessment evaluations were performed on several samples of trap grease, trap grease biodiesel, and reference materials to illustrate different aspects of their odor profile and to gain a better understanding of the odor sources so odor mitigation strategies can be developed and evaluated. Short-chain free fatty acids have been identified as a significant component in trap grease and the odor descriptors commonly associated with short-chain free fatty acids were identified in the trap grease samples evaluated. Biodiesel was prepared from trap grease and found to have a similar odor profile as petrodiesel and other commercially available biodiesels blends. The results from this study show that the odor from trap grease can be mitigated during pretreatment and biodiesel conversion steps and does not represent a significant obstacle to commercialization.