Date of Award

4-2024

Degree Name

Master of Science

Department

Chemistry

First Advisor

Andre Venter, Ph.D.

Second Advisor

Ekkehard Sinn, Ph.D.

Third Advisor

Ramakrishna Guda, Ph.D.

Keywords

Atmospheric pressure chemical ionization, electrospray ionization, hops bittering compounds, hops sample, HPLC, ICE-4 standard

Access Setting

Masters Thesis-Open Access

Abstract

Hops acids are essential components in the beer brewing process containing alpha acids (α-acids) and beta acids (β-acids) as the major hops bittering compounds. Quantifying these acids is vital for quality control and determining bitterness levels and hops variety profiles. Current industry standards, like High-Performance Liquid Chromatography with Ultraviolet detection (HPLC-UV) and Ultraviolet Spectroscopy (UV-Vis), though effective, are time-consuming and solvent-intensive, providing incomplete information.

This research introduces a novel method using mass spectrometry with atmospheric pressure chemical ionization (APCI-MS) to analyze hops bittering acids without chromatographic separations. This approach offers rapid analysis, high throughput, and eco-friendliness.

Comparison with direct electrospray ionization mass spectrometry (ESI-MS) focuses on differences in figures of merit of the calibration curves, ionization suppression, and accuracy. APCI-MS boasts significant advantages: analyzing samples in about 1 minute versus HPLC’s 15- 30 minutes, while using less solvent. Additionally, APCI-MS shows lower detection limits, reduced ion suppression, and improved accuracy compared to ESI-MS. This method promises to streamline hops analysis in brewing, enhancing efficiency and data quality.

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