In order to locate the key antioxidants contributing to oxidative stability of beer, activity-guided fractionation in combination with the oxygen radical absorbance capacity (ORAC) assay, hydrogen peroxide scavenging (HPS) assay, and linoleic acid (LA) assay was applied to a pilsner-type beer. LC-MS and 1D/2D NMR experiments led to the identification of a total of 31 antioxidants, among which 3-methoxy-4-hydroxyphenyl-β-d-glucopyranoside (tachioside), 4-(2-formylpyrrol-1-yl)butyric acid, 4-[2-formyl-5-(hydroxymethyl)pyrrol-1-yl]butyric acid, n-multifidol-3-O-β-d-glucoside, quercetin-3-O-(6″-malonyl)-glucoside, 4-feruloylquinic acid, syringaresinol, saponarin, and hordatines A-C have been isolated from beer for the first time. On a molar comparison, the hordatines A-C, saponarin, and quercetin-3-O-β-d-(6″-malonyl)glucoside were evaluated with the highest antioxidant activities of all identified beer constituents, reaching values of 10-17.5 (ORAC), 2.0-4.1 (HPS), and 1.1-6.1 μmol TE/μmol (LA) for hordatines A-C.

Sensory-guided fractionation of extracts of Tasmanian pepper berries revealed 20 drimane sesquiterpens, among which polygodial, warburganal, and 1β-acetoxy-9-deoxy-isomuzigadial exhibited the lowest pungency threshold concentrations on the tongue surface (0.6-2.8 nmol/cm) and elicited a dose-dependent calcium influx into mTRPA1 expressing CHO cells with the lowest EC values (4.5 ± 1.0 to 16.7 ± 7.5 μmol/L) and a good correlation to oral pungency thresholds (R = 0.986, linear regression). Calcium imaging assays demonstrated these chemosensates to induce a calcium influx into cultured trigeminal neurons prepared from wildtype (TRPA1) mice, whereas no calcium influx was observed in neurons from TRPA1 knockout mice (TRPA1), thus confirming the α,β-unsaturated 1,4-dialdehyde structure to be the required structural motif for a low oral puncency thresholds and activation of the Transient Receptor Potential Channel A1 (TRPA1). Time-resolved NMR experiments confirmed the pungency mediating mechanism for electrophilic drimane sesquiterpene dialdehydes to be different from that found for other electrophilic pungent agents like isothiocyanates, which have been shown to undergo a covalent binding with cysteine residues in TRPA1. Instead, the high-impact chemosensates polygodial, warburganal, and 1β-acetoxy-9-deoxy-isomuzigadial showed immediate reactivity with the ε-amino group of lysine side chains to give pyrrole-type conjugates, thus showing evidence for TRPA1 activation by covalent lysine modification.

Altitude profiles of the stratospheric trace gases HNO3 and HCN were simultaneously measured by a balloon‐borne mass spectrometer, which was launched on 13 February, 1992 at Kiruna (68°N, 20°E, Northern Sweden). The HCN‐profile is nearly constant, around 0.18 ppbv, which is similar to previously measured midlatitude data. The HNO3‐profile measured below 24 km on the descent part of the balloon flight is similar to NOy (≲20ppbv), and becomes smaller than NOy above 24 km. Probably, the large HNO3, below 24 km, reflect heterogenous HNO3‐formation by H2SO4‐H2O aerosols from volcano Pinatubo. On ascent HNO3 was substantially decreased around 18 to 24 km, which was possibly due to HNO3‐dissolution in H2SO4‐H2O aerosols.

The formation pathways of α-diketones (2,3-butanedione and 2,3-pentanedione) and 4-hydroxy-2,5-dimethyl-3­(2H)-furanone (HDMF) upon coffee roasting were investigated in a kinetic study applying labeled and unlabeled sucrose (CAMOLA approach) in biomimetic in-bean experiments. The results highlighted that not only did the contribution of sucrose to the level of α-diketones in roasted coffee change with the roasting degree but also the portion of the individual reaction pathways. At early roasting stages, 2,3-butanedione was formed from sucrose mainly via the intact sugar skeleton, whereas from the middle of the roasting course, the formation foremost occurred from sugar fragments, primarily by C1/C3 and C2/C2 recombinations. In contrast, 2,3-pentanedione was generated from sucrose mainly via an intact sugar skeleton during the whole roasting cycle; nevertheless, the share of 2,3-pentanedione formed by recombination of fragments (mainly C2/C3) progressively increased with roasting time. HDMF was generated from sucrose almost exclusively via cyclization of an intact skeleton, irrespective of the roast time.