9-51: Possible co-products from Sweetgum (Liquidambar styraciflua L.)

Sweetgum (Liquidambar styraciflua L.) is an understory, hardwood species that has a widespread distribution in the southeast United States, and is of interest due to its co-existence in forest management areas that are logged for softwoods such as pine.  Sweetgum trees must be harvested prior to logging, and represent a residue biomass that can be utilized in the production of cellulosic biofuels.  In addition, valuable co-products can be extracted by distillation from the sweetgum leaves, fruit and annual stems.  These co-products include flavonoids, such as shikimic acid, which is a component of an antiviral drug, and terpenoids, which are thought to have therapeutic properties similar to tea tree oil.  The antimicrobial properties of sweetgum extracts may develop into a use in the food industry. Listeria monocytogenes, a gram-positive foodborne pathogenic bacterium, can cause listeriosis, which has a mortality rate of nearly 28%. The objective of this study is to determine if antimicrobial compounds, such as flavonoids and terpenoids, can be extracted from sweetgum prior to its conversion to biofuels. It is important that the compounds are extracted by water distillation so that the extraction step does not hinder the ensuing pretreatment, enzymatic hydrolysis and fermentation steps.  Water is an excellent solvent for the extraction of co-products because it does not interfere with biomass conversion to energy by decreasing yields or adding processing steps. Preliminary results indicate that sweetgum water extracts have inhibitory effects against L. monocytogenes and Escherichia coli O157:H7.