Beer metabolomics: molecular details of the brewing process and the differential effects of late and dry hopping on yeast purine metabolism

Abstract

The flavour of beer is complex, based upon changes at the molecular level in the key raw materials, notably grain, hops and yeast, as well as during the process stages that comprise malting and brewing. As analytical techniques evolve in their sophistication and sensitivity, there are opportunities to delve ever more deeply into the fate of small molecules in brewing. To this end, 1 H nuclear magnetic resonance (NMR) metabolomics was used to follow the progression of 76 metabolites in four different late or dry hopped beers (brewed in triplicate) at five time points throughout the brewing process. The majority of the metabolites identified, including sugars, amino acids and nucleotides, significantly decreased in concentration from the start of the boil to post-secondary fermentation, whereas energy-related and fatty acid associated metabolites significantly increased in concentration as wort nutrients were consumed by the yeast. Adenine was significantly higher in the dry hopped brews than in the late hopped brews after both primary (p = 2.1 × 10 À6 ) and secondary (p = 2.7 × 10 À9 ) fermentation, while 2′-deoxyadenosine (after primary, p = 1.1 × 10 À2 , after secondary, p = 3.2 × 10 À5 ) and adenosine (after primary, p = 2.6 × 10 À8 ; after secondary, p = 3.1 × 10 À7 )were significantly lower in the dry hopped beers at these time points. These results give molecular insight into the brewing process and the differential effects of hopping methods on yeast purine metabolism.

Nuclear Magnetic Resonance (NMR) Spectroscopy in Food Science: A Comprehensive Review

“…NMR spectroscopy has been used for the quality control of foods in terms of monitoring stability (Alonso‐Salces, Holland, & Guillou, ; Guillen & Goicoechea, ; Lamanna, Piscioneri, Romanelli, & Sharma, ; Souza, Martínez, Ferreira, & Kaiser, ), storage history (Belloque et al., ; Fronimaki et al., ; Graham et al., ), packaging (Pentimalli et al., ), safety (Beer et al., ; Marchand et al., ; Monakhova, Kuballa, & Lachenmeier, ), evaluation of agronomic practices (Consonni et al., ; Gallo et al., ; Jahangir et al., ; Winning et al., ; Zhang, Breksa, Mishchuk, & Slupsky, ), and studying process‐induced effects (Alves Filho et al., ; García‐García, Lamichhane, Castejón, Cambero, & Bertram, ; Lopez‐Sanchez et al., ; Sinanoglou et al., ; Vermathen et al., ; Wakamatsu, Handa, & Chiba, ; Zoumpoulakis et al., ; Hwang et al, ). Characteristic examples of foods include fish (Erikson et al., ; Martinez et al., ; Tan et al, ), meat (Straadt, Aaslyng, & Bertram, ), spices (Cagliani, Culeddu, Chessa, & Consonni, ; Ordoudi et al., ), beverages (Almeida et al., ; Le Gall, Colquhoun, & Defernez, ; Spevacek, Benson, Bamforth, & Slupsky, ; Walch, Stühlinger, Lachenmeier, Monakhova, & Kuballa, 2012a), oils (Lucas‐Torres, Pérez, Cabañas, & Moreno, ), and dairy products (Maher & Rochfort, ; Shintu & Caldarelli, ). Recently, NMR, combined with statistical analysis, was used to determine the quality of salmon relating to its storage conditions (Shumilina, Dykyy, & Dikiy, ).…”

Decomposing the molecular complexity of brewing

“…Profiling of volatile fingerprints of hops and barley 19 , yeast strains 20 , or different beer types 21 was carried out by means of either headspace or bubbling burst (GC)-MS analysis. Besides mass spectrometry, nuclear magnetic resonance (NMR) spectroscopy was applied to beer analysis to differentiate beer types 22 , brewing sites 23 , raw materials, or influences on yeast fermentation 24 . The range of analyzed molecules, which characterize the differences of the samples, reaches from carbohydrates, amino acids, small organic acids over bitter acids, (poly)phenols and purines to more volatile terpenes, esters, alcohols, aldehydes, and ketones.…”

Translational Metabolomics: Current Challenges and Future Opportunities

“…The strains of yeast and bacteria used can also have an impact on the small molecule profile of the wine, which has been extensively investigated by 1 H NMR [169]. Similar metabolomics studies have been carried out for other fermented foods, including beer [170], soy sauce [171] and others fermented products. Although these applications are not directly linked to a simple form of industrial translation, metabolomics is playing a major role in regard to a better process control.…”