Occurrence of Odorant Polyfunctional Thiols in the Super Alpha Tomahawk Hop Cultivar. Comparison with the Thiol-rich Nelson Sauvin Bitter Variety

Abstract

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.

Occurrence of the ribes odorant 3‐sulfanyl‐3‐methylbutyl formate in aged beers

“…[17] Very recently, Gros et al described the presence of various other sulfanyl acetates in hop, especially in the Tomahawk and Nelson Sauvin varieties: 1-sulfanyl-3-butyl acetate (plastic/ sprout), 3-sulfanylbutyl acetate (cheese), 3-sulfanyl-2-methylpropyl acetate (grilled nut descriptor), 3-sulfanyl-2-ethylpropyl acetate (floral), 3-sulfanyl-2-methylbutyl acetate (cooked meat), 3-sulfanyl-3-methylbutyl acetate (pepper), 4-sulfanyl-4-methyl-2-pentyl acetate (grilled nut), 3-sulfanylpentyl acetate (peach), 1-sulfanyl-3-pentyl acetate (cheese), 3-sulfanylhexyl acetate (candy) and 3-sulfanyloctyl acetate (catty). [9] Hop proved not to contain any sulfanyl formates. Likewise, only sulfanyl acetates were found in the corresponding Tomahawk-derived beers.…”

“…[7,8] It is even often used as an internal standard for beer thiol extraction. [9] With the aroma extract dilution analysis technique applied to an aged beer extract, Schieberle revealed the possible relevance of 3-sulfanyl-3-methylbutyl formate to the beer ribes note. [10] Its threshold in water is assessed at 2-5 ng/l.…”

“…Likewise, only sulfanyl acetates were found in the corresponding Tomahawk-derived beers. [9,18] The onion-like 3-sulfanyl-3-methylbutan-1-ol and its isomer, 2-sulfanyl-3-methylbutan-1-ol, have been identified in fresh beer by gas chromatography-olfactometry (GC-O), gas chromatography-pulsed flame photometric detection (GC-PFPD) and gas chromatography-mass spectometry (GC-MS), suggesting a possible transformation to the corresponding formates through ageing. Gros et al [19] have shown that these sulfanyl alcohols arise in beer through radical and electrophilic addition of yeast-excreted hydrogen sulfide to the hop allylic alcohol 3-methylbut-2-en-1-ol.…”

Enzymatic release of odourant polyfunctional thiols from cysteine conjugates in hop

“…Hop is the main contributor of thiols to beer . The compounds 3‐sulphanyl‐4‐methylpentan‐1‐ol, 3‐sulphanyloctan‐1‐ol, and 3‐sulphanylhexan‐1‐ol distinguish Nelson Sauvin‐, Tomahawk‐, and Cascade‐hopped beers, respectively .…”

Preparation and Odour Properties of (S)-3-Mercapto-1-Heptyl Acetate

“…In particular, polyfunctional thiols and their derivatives having pronounced odour qualities have been the subject of many publications. [6][7][8][9][10][11] A lot of compounds containing 1,3-oxygensulfur functionality, such as 3-mercapto-1-hexanol and its derivatives, 12 and 4-mercapto-2-heptanol and its derivatives, 13 have been found to possess tropical, fruity or vegetable odour notes. As a result, the 1,3-oxygen-sulfur functionality has been described as the "olfactophore" for these notes.…”