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Malted red sorghum (Sorghum bicolor) is used as raw material in many traditional beers including Ikigage in Rwanda. In East African countries, sorghum malting may involve adding wood ashes. Mashing traditional sorghum malted with 5% eucalyptus ashes leads to a remarkable increase of EBC congress wort yield (64-69% against 15-22% without ash). Similar mashing yields can be obtained when a ratio of only 20% sorghum with ashes is used, or if ashes are added just prior mashing. Adjusting the wort pH to 6.5 with 1 M NaOH only partially mimics the presence of ashes (mashing yield = 39%). Total polyphenol and total flavanoid measurements, HPLC/UV quantitation of flavan-3-ols and ORAC antioxidant activities enabled us to show that the great benefit of ashes mainly comes from a 63-76% decrease in sorghum polyphenols. [ABSTRACT FROM AUTHOR]

At present, non-alcoholic beers and low-alcoholic beers (NABLABs) suffer from premature oxidation when fresh, and from a lack of fruity fermentation aromas. In wines, dimethylsulfide (DMS) is known to enhance truffle nuances and the fruity character. This offers an opportunity to improve the flavor of NABLABs. In this work, levels of free DMS and its potential precursors (S-methylmethionine/SMM and dimethylsulfoxide/DMSO) were assessed in eleven commercial NABLABs, in parallel with their amounts of fruity esters and polyfunctional thiols. Except in two dry-hopped samples and a fruity beer, free DMS was detected at very low levels in all fresh NABLABs (four samples even displayed no detectable GC peak), likely because of dealcoholization or too-short fermentation. Through NABLABs aging, the free DMS concentration increased (+63% on average after two years), at a degree correlated with the initial SMM level (2–118 µg/L DMS eq.; R2 = 0.79). This SMM amount revealed to be also correlated with the group I amino acid residual content (more consumed through traditional fermentations). Unlike DMSO, SMM showed significant release of free DMS after aging in spiking experiments (4% degradation after 30 days at 20 °C). As fruity fermentation esters are found in NABLABs at much lower concentrations than in conventional lagers, increasing both DMS and polyfunctional thiols by dry hopping (or DMS-enriched extracts) emerges as an opportunity to improve them. [ABSTRACT FROM AUTHOR]

Even when fresh, non-alcoholic, and low-alcoholic beers (NABLABs) exhibit significant staling defects due to premature oxidation. In this study, the antioxidant power of eleven fresh commercial NABLABs was assessed by means of three different assays: the oxygen radical absorbance capacity (ORAC), the linoleic acid-induced oxidation (TINH), and the indicator time test (ITT). Only the first two assays, both involving radicalar degradations initiated by AAPH, were found to correlate with each other. NABLABs displayed lower ORAC values than conventional beers (on average, 6127 μmol eq. Trolox/L), except for three samples made with special-colored malts or dry-hopped. Dealcoholization was the step with the greatest impact on the ORAC value (up to a 95% loss) and on flavan-3-ols, sotolon, and polyfunctional thiols, while pasteurization strongly affected color, TBA, and Strecker aldehydes. ORAC assays applied to hop, alternative cereals, and various botanical ingredients indicated that mashing with red sorghum, dry hopping/spicing, and wood maturation could bring the antioxidant power of a NABLAB close to those of conventional beers. With an ORAC value not reached by any other tested botanical ingredient (5234 µmol eq. Trolox/g), African Vernonia amygdalina leaves (traditionally used for Rwandan Ikigage beers) emerged here as the best candidate. [ABSTRACT FROM AUTHOR]

At present, non-alcoholic (NAB) and low-alcoholic beers (LAB) exhibit major staling defects even when fresh, partly due to absence of ethanol as an antioxidant. In the present work, the aroma stability of eleven commercial NABLABs available on the Belgian market, issued from different technological processes, was assessed. NABLABs were investigated, both when fresh and after one year of storage at 20 °C in the dark. Six stale-odorant compounds were found above their perception threshold in aged NABLABs: sotolon, abhexon, methional, phenylacetaldehyde, dimethyltrisulfide and β-damascenone. Based on the chemical structure of the first four, it can be concluded that oxidation is the main issue for NABLABs aging. Yet, five of these usual staling defects of a six-month lager beer were already key-odorants in fresh NABLABs: dimethyltrisulfide, methional, and β-damascenone were above the thresholds in all samples, phenylacetaldehyde in 10 out of 11, and sotolon in 7. In conclusion, development of efficient antioxidants is needed to improve NABLABs acceptability. [ABSTRACT FROM AUTHOR]

Dry hopping imparts distinct aromas but also a series of non-volatile compounds suspected of causing flavor and physical instability during beer storage. In this work, color, chill haze, total polyphenols, total flavanoids, and flavan-3-ol monomers (catechin and epicatechin) and oligomers (procyanidin dimers and trimers) were monitored in five commercial pale-colored Belgian dry-hopped beers over 24 months of storage at 20 °C in the dark. Fresh dry-hopped beers contained unusually high levels of flavan-3-ol monomers (up to 6.6 mg/L) and oligomers (up to 14.1 and 10.2 mg/L dimers and trimers, respectively). The increase in color intensity during storage (up to 6.4°EBC) correlated with fresh beer monomer levels, while the oligomer content correlated with chill haze formation (up to 25.7°EBC). The evolution of these two physical attributes also correlated with the level of total polyphenols in the fresh beers. In a pilot-scale production, kettle hopping was shown to impart either monomers (early) or oligomers (late), while dry hopping promoted efficient extraction of both monomers and dimers (extraction yields of 62 and 74%, respectively). Dry hopping thus plays an important role in color and chill haze increase. [ABSTRACT FROM AUTHOR]