Barnette, B. M.1 and Shellhammer, T. H.1, (1)Oregon State University, Corvallis, OR, USA
Poster
Brewer’s spent grain has commercial and nutritional value, yet it may contain hop acids. This study focused on the adaptation of ASBC Method of Analysis Hops-14 to quantify residual hop acids contained in brewer’s spent grain. Trials to determine the presence of iso-alpha, alpha, and beta hop acids in dried spent grain were carried out to test the feasibility of detection and quantification by HPLC analysis. Dose and recovery studies were carried out to evaluate the recovery rates in spent grain dosed with a mixture of purified hop acids. Once the method was validated for its ability to detect the hop acids under controlled conditions, an evaluation of limit of detection (LD) and limit of quantification (LQ) was carried out to better understand the limitations of the modified Hops-14 method. Recovery rates of the various hop acids ranged from 94% to 106%. The method yielded LD and LQ values of 0.4–1.0 mg/L and 0.6–1.4 mg/L in extraction solution, respectively, depending on the hop acid component in question. Detection limits in the spent grain were influenced by the spent grain/extraction solvent ratio and were 1.4, 1.0 and 1.8 mg/L for total iso-alpha-, alpha- and beta-acids, respectively. Further processing of the extraction solvent was deemed not necessary and clouded the chromatogram with excess baseline signal from the grain matrix. With this adaptation of Hops-14, it is feasible to evaluate a sample of spent brewer’s grain for the presence of iso-alpha, alpha, and beta hop acids.
Bradley Barnette is a first-year master’s degree student in the Brewing Science Department at Oregon State University. He received a bachelor’s degree in food science and technology, as well as a bachelor’s degree in general science from Oregon State University. His project work thus far has included method development and chemical analysis of hop samples for the Oregon State hop breeding program. His current research interests are focused on beer bitterness, beer staling and flavor stability, hop analytics, and instrumental analysis of hops and hop products.
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