Tomahawk hop (Humulus lupulus) is a recently developed Super Alpha cultivar (14-18% α-acids w/w), already widely used by brewers to impart bitterness and a citrus-like aroma to beer. By comparison with two bitter varieties (Nelson Sauvin and Nugget) and two aromatic ones (Cascade and Saaz), the Tomahawk cultivar showed a very particular terpenoid profile, rich in both α- and β-selinenes (>600 mg/kg IST equiv in total), methyl geranate (>40 mg/kg IST equiv), and geraniol (>200 mg/kg). Tomahawk also proved to contain a wide variety of odorant polyfunctional thiols. The major β-sulfanyl acetate, 3-sulfanyl-2-ethylpropyl acetate, newly identified here, was found at similar levels in the famous Sauvignon-like Nelson Sauvin and Tomahawk varieties (15-44 μg/kg IST equiv). On the other hand, lower levels of total β-sulfanyl alcohols were measured in Tomahawk, although 3-sulfanylhexan-1-ol was found at a similar level and the 3-sulfanyl-4-methylpentan-1-ol previously claimed to be specific to the Nelson Sauvin variety was also evidenced in the Super Alpha cultivar (9-13 μg/kg IST equiv). As revealed by boiling and fermentation, Tomahawk hop also contains very interesting bound polyfunctional thiols that should be investigated for better use by brewers.

Forty-one thiols, mainly β-sulfanylalkyl acetates, β-sulfanylalkyl alcohols, and β-sulfanylalkyl carbonyls, were recently evidenced in hop. In a beer hopped with the Tomahawk cultivar, most of them were found at higher levels than expected. The aim of the present work was to investigate the polyfunctional thiols in beers hopped with different varieties. A few thiols proved not to come only from hop (mainly 2-sulfanylethyl acetate, μg/L levels, and 1-sulfanylpentan-3-one and 1-sulfanylpentan-3-ol, ng/L levels, internal standard (IST) equivalents). The thiol profile of Saaz-hopped beer proved similar to that of the reference beer produced without hop. A high level of 3-sulfanyloctan-1-ol emerged as an indicator of the use of Tomahawk hop (140 ng/L, IST equivalents; FD (flavor dilution) = 65536). In both Cascade- and Tomahawk-hopped beers, 3-sulfanylhexan-1-ol and 3-sulfanylheptan-1-ol were smelled at high flavor dilutions, although only for the latter, significant amounts of the unreduced 3-sulfanylheptanal were found in hop. As already claimed for hop authentication, 3-sulfanyl-4-methylpentan-1-ol remains a good marker of Nelson Sauvin-hopped beers (548 ng/L, IST equivalents; FD = 65536), together with 4-sulfanyl-4-methylpentan-2-one (128 ng/L, FD = 4096). As illustrated by the huge production occurring during fermentation, accurate prediction of hop varietal impact requires quantitating thiol adducts in hop. S-3-(1-Hydroxyhexyl)cysteine was evidenced here for the first time in Cascade hop.

Free terpenoids and both free and bound polyfunctional thiols were investigated in five selected dual-purpose hop cultivars. Surprisingly, the dual-purpose Sorachi Ace variety was found to contain higher amounts of farnesene (2101 mg/kg) than aromatic hops such as Saaz but only traces of 3-methylbutylisobutyrate, a compound that usually distinguishes all bitter varieties. All five cultivars investigated here showed an exceptional citrus-like potential explained by either monoterpenic alcohols or polyfunctional thiols. Among the monoterpenic alcohols, β-citronellol at concentrations above 7 mg/kg distinguished Amarillo, Citra, Hallertau Blanc, Mosaic, and Sorachi Ace from Nelson Sauvin and Tomahawk, two previously investigated dual-purpose hops, while linalool (312 mg/kg) and geraniol (211 mg/kg) remained good discriminating compounds for Nelson Sauvin and Tomahawk, respectively. Regarding polyfunctional thiols, higher amounts of 3-sulfanylhexyl acetate (27 μg/kg) characterized the Citra variety. Free 4-sulfanyl-4-methylpentan-2-one proved discriminant for Sorachi Ace, while the bound form is predominant in Nelson Sauvin. On the other hand, an S-conjugate of 3-sulfanylhexan-1-ol was found in Sorachi Ace at levels not far from those previously reported for Cascade, although the free form was undetected here. Both free and bound grapefruit-like 3-sulfanyl-4-methylpentan-1-ol (never evidenced before the present work) emerged as discriminating compounds for the Hallertau Blanc variety. The apotryptophanase assay also allowed us to evidence for the first time an S-conjugate of 2-sulfanylethan-1-ol.

Eleven mineral fractions from the Allende C3 chondrite were analyzed for He, Ne, Ar, Kr, and Xe by mass spectrometry. As was shown previously (Lewis et al., 1975), most of the heavy noble gases, of unexceptional isotopic composition, are contained in an ill‐defined HNO3‐soIuble mineral fraction (‘Q’) comprising 0.04% of the meteorite. The remaining noble gases, of decidedly nonsolar isotopic composition, are contained in chromite (0.2%) and amorphous carbon (0.2%). They have virtually identical concentrations and isotopic compositions in the two minerals: 20Ne/22Ne = 8.7 and 36Ar/38Ar = 4.82. Xenon is enriched up to twofold in both heavy and light isotopes, while Kr is enriched only in heavy isotopes. The enrichment of the heavy isotopes is presumably due to fission, but the fission spectra derived depend critically on the assumed composition of the trapped component. The enrichment patterns of the light xenon isotopes differ slightly for chromite and carbon. Partial destruction of the minerals by chemical treatments gave no evidence for other gas‐rich phases or other gas components and only orginal evidence for heterogeneities within the known gas‐rich phases. Spinel has ≪0.1 the gas content of other phases. The chromite‐carbon fractions contain 30–60% more spallogenic 21Ne than does the bulk meteorite, although they are deficient in target elements for the production of 21Ne. A possible explanation is recoil of 21Ne from adjacent Mg‐rich phases. All of the available isotopic and chemical data suggest that chromite, carbon, and Q, and hence their associated gas components, are of local rather than extra‐solar system origin. The excess heavy Kr and Xe isotopes may have been produced by fission of a superheavy element, while the remaining isotopic anomalies may be due to mass fractionation during trapping. The virtual identity of the noble gas components of chromite and carbon suggests that both minerals formed simultaneously, perhaps by a reaction such as Fe + 2Cr + 4CO → FeCr2O4 + 4C.

Polyfunctional thiols are contributors to the hop varietal aroma of beer. Besides free thiols, a cysteine-S-conjugate has recently been shown to be an additional component of the thiol potential of hop. Such cysteine adducts investigated here in four hop cultivars and in different hop forms. Hop hydroalcoholic extracts were purified on a cation exchanger and subjected to apotryptophanase β-lyase activity. The Cascade hop variety exhibited the highest bound 3-sulphanylhexan-1-ol (grapefruit-like) potential, while both Tomahawk and Nelson Sauvin cultivars were confirmed to be important sources of bound 3-methyl-2-butene-1-thiol (skunky-like), 3-sulphanylpentan-1-ol and 4-sulphanyl-4-methylpentan-2-one (box-tree-like). Surprisingly, hop CO 2 extracts proved to contain cysteine conjugates. Although related, the concentrations of cysteine-bound thiols in hop are not strictly correlated to the amounts of free volatiles found in the derived beers.