Characterization of Key Aroma Compounds in Pellets of Different Hop Varieties (Humulus lupulus L.) by Means of the Sensomics Approach

Abstract

The use of hops in beer brewing is mainly based on its content of bitter acids and aroma compounds. Due to the loss of volatile odorants during wort boiling, the so-called dry hopping is a possibility to intensify the hoppy aroma in the final beer. To clarify the potential of different hop varieties for aroma modulation of beer via dry hopping, key aroma compounds of three different hop varieties were characterized using the sensomics approach. Aroma extract dilution analysis revealed 41 aroma-active compounds, of which 39 were identified via gas chromatography-olfactometry and gas chromatography-mass spectrometry. The highest flavor dilution factor was determined for myrcene with a geranium-like odor. Fourteen substances were quantitated by stable isotope dilution analysis and further two odorants via the internal standard method; all of them revealed odor activity values (OAVs; ratio of concentration to odor threshold) ≥1. Linalool, 3-methylbutanoic acid, myrcene, and dimethyl trisulfide showed the highest OAVs (>1000) in all analyzed hop varieties. For validation of the analytical data, reconstitution models were prepared by adding all quantitated aroma compounds with OAVs ≥ 1 in their naturally occurring concentrations to cellulose as matrix. All three recombinates showed a very high similarity to the aroma profile of the respective hop sample, confirming the correct identification and quantitation of all key aroma compounds.

Co-fermentation Involving Saccharomyces cerevisiae and Lactobacillus Species Tolerant to Brewing-Related Stress Factors for Controlled and Rapid Production of Sour Beer

“…The highest concentration of organic acids was obtained in the L. brevis beer (942 ± 11 mg/L acetic, 2598 ± 56 mg/L lactic, and 196 ± 14 mg/L succinic acid, Supplementary Table S3) followed by the L. plantarum beer (89 ± 26 mg/L acetic, 1792 ± 94 mg/L lactic, and succinic acid below detection, Supplementary Table S3), while no lactic acid or succinic acid and only a limited amount of acetic acid (31 ± 4 mg/L, Supplementary Table S3) was generated in the reference beer. Lactic acid is associated with acidity and sourness (Van Oevelen et al, 1976) and has a reported taste threshold of 400 mg/L (Engan, 1974). Acetic acid is associated with acidity, sour (Engan, 1974) and vinegary flavors (Van Oevelen et al, 1976) and has a reported sensory threshold of 200 mg/L (Engan, 1974).…”

“…Lactic acid is associated with acidity and sourness (Van Oevelen et al, 1976) and has a reported taste threshold of 400 mg/L (Engan, 1974). Acetic acid is associated with acidity, sour (Engan, 1974) and vinegary flavors (Van Oevelen et al, 1976) and has a reported sensory threshold of 200 mg/L (Engan, 1974). Both lactic and acetic acid were well above reported sensory thresholds in the L. brevis beer, which corresponds well with this beer being perceived as significantly higher than the L. plantarum and the reference beer in acidic taste in the sensory analysis ( Figure 5C and Supplementary Table S4).…”

Studies on the odorant concentrations and their time dependencies during dry‐hopping of alcohol‐free beer

“…Every 24 hours, the concentrations of eight different odorants (ethyl 2-methylbutanoate, ethyl 3-methylbutanoate, ethyl methylpropanoate, geraniol, linalool, methyl 2-methylbutanoate, myrcene, and propyl 2-methylbutanoate) were determined, which have already been identified as important odorants in hops and dry-hopped alcohol-free beer. 1,10 For geraniol, linalool, and myrcene, the maximal transfer rates were reached after 2-3 days (Figure 1). Afterwards, a decline in concentrations was observed.…”

“…By applying the molecular sensory science concept, linalool, myrcene, 3-methylbutanoic acid, and geraniol were identified as important aroma-active compounds in hop varieties. [1][2][3] For some hops, variety-specific odorants were identified like ethyl 2-methylbutanaote in Huell Melon or 4-mercapto-4-methylpentan-2-one in US varieties like Cascade, Citra, and Eureka. 4 Especially by late-or dry-hopping, higher concentrations of these hop odorants can be achieved in the final product.…”

Hop-induced formation of ethyl esters in dry-hopped beer

“…Hallertauer Mandarina Bavaria hop pellets type 90, harvest year 2015, were provided by Hopsteiner (Mainburg, Germany). Identification and quantitation of odorants in this batch have already been performed in a previous study (Brendel et al 2019). Hop extracts were also provided by Hopsteiner: Alpha extract contained 20.0 ± 1.0% α-acids.…”