Date of Graduation
5-2025
Document Type
Thesis
Degree Name
Bachelor of Science in Agricultural, Food and Life Sciences
Degree Level
Undergraduate
Department
Food Science
Advisor/Mentor
Scott Lafontaine
Abstract
The production of India Pale Ales (IPAs) has significantly grown within the U.S. craft beer industry, with IPAs accounting for nearly 44% of the total craft beer production by 2022. This increase in IPA production correlates with a rise in U.S. aroma hop cultivation, as IPAs typically undergo dry hopping, a process that enhances their aromatic profile. In a study conducted by Lafontaine et al., (2022), it was found that different hop cultivars can impact levels of metallic character in a final product from dry hopping. When specifically analyzing iron concentrations, it can be seen that the ranges of iron in dry hopped be varied from 10.9-40.4µg/L depending on the beer style and hop cultivar. However, due to lack of research in flavor thresholds for beer, brewers are currently unaware of the specific concentration levels at which these transition metals begin to negatively impact the flavor characteristics of their beer. This lack of clarity makes it difficult for brewers to control metal concentrations effectively and avoid undesirable off-flavors. This study aims to determine the flavor thresholds of iron sulfate (FeSO₄) and iron III chloride (FeCl₃) in nonalcoholic beer (NAB). A sensory analysis involving 22 panelists was conducted using a triangle test methodology to assess detection thresholds for these two transition metals. Results showed that the detection thresholds for FeSO₄ ranged from 75.52-605.28 µg/L, while FeCl₃ ranged from 47.48-818.83 µg/L, with all observed thresholds exceeding typical iron concentrations found in dry-hopped beers (Lafontaine et al., 2022). These findings suggest that iron alone does not contribute to metallic off-flavors in beer. However, the study indicates a need for further research into the interaction of iron with other transition metals in beer, which may affect flavor perception. This research provides valuable data for brewers to refine metal concentrations in beer production, potentially enhancing sensory quality in both alcoholic and non-alcoholic beers.
Keywords
Triangle test; Metallic flavor thresholds; Nonalcoholic beer; Dry hopping
Citation
Hood, A. (2025). Determining the Flavor Thresholds of Iron Sulfate and Iron (III) Chloride in Nonalcoholic Beer. Food Science Undergraduate Honors Theses Retrieved from https://scholarworks.uark.edu/fdscuht/19
