Kalli Martinez, Undergraduate
Emily Gaston, ESRM
Environmental Science and Resource Management
Microplastics are small pieces of plastic that are no bigger than 5mm, found in terrestrial, marine and urban environments. This project specifically looks at microplastic abundance and distribution throughout the brewing process between three Ventura County breweries (Brewery A, B, C). The samples collected were three samples each of city water, post-R.O. water, pre- and post-boil, and final product (hazy and clear IPA). These stages were selected due to the likelihood of being contaminated to microplastics throughout the brewing process. The samples were centrifuged to separate solids and liquids, run through a vacuum filtration, digested for 24-hours using Fenton’s Reagent and 30% Hydrogen Peroxide in a water bath at 23.7˚C, then filtered. Microplastics on the filters were enumerated and characterized by color and type. The results showed how microplastic abundance fluctuates throughout the brewing process and how the difference in brewing styles can have an effect on microplastic abundance. In Brewery A, stages where there was an addition of ingredients is when more microplastics were found. Brewery B showed an abundance of microplastics in the Post-Boil stage. Brewer C showed no contamination trend that could be noted. Conversely, stages where the beer was not exposed to open air or went through a form of boiling and filtration had less microplastics. From these results, it can be concluded that stages that were exposed to open air had contamination from airborne plastics. Stages where ingredients and their products were being boiled had less microplastics. Between the three breweries, the clear IPAs had significantly less microplastics than the hazy IPA. This is could be due to the amount of final filtration or clearing reagent added that the clear IPA goes through to sieve out unwanted ingredients to get a certain taste. General contamination across all stages sampled and their blanks could come from a number of sources, however, it is thought to come from transfer, air, containers, or even the researchers themselves.