Formation of 4-Hydroxyfuranones and their Precursors during Production of Worts and Beers

Abstract

Laboratory beers and samples taken at each stage of production, were analysed for the flavour active 4-hydroxyfuranones; 5-methyl-4-hydroxy-3(2H)-furanone (MHF), 2,5-dimethyl-4-hydroxy-3(2H)-furanone (DMHF) and 5-(or 2)-ethyl-2(or 5)-methyl-4-hydroxy-3(2H)-furanone (EMHF). The length and temperature of mashing, the length of boiling, the rate of cooling the worts and the effects of grist composition were investigated to identify the 4-hydroxyfuranone content of worts and subsequent beers. Fermentation temperature and the use of the stabilising agents, PVPP and Lucilite PC5, on the 4-hydroxyfuranone content of the beer was also investigated. The results demonstrated that several aspects of beer production procedures affect the furanone content of the beer, but in practice the important factors are grist composition, the rate at which the boiled wort is cooled and fermentation temperature. Fermentation has a major effect on final furanone content as yeast produces both DMHF and EMHF. The results suggest that malt levels of precursor compounds, which can be converted to 4-hydroxyfuranones by the Maillard reaction or by yeast, may prove to be more important than the quantities of the furanones found in malt in determining the final furanone content of beer. A clearer understanding of the nature of the precursors should allow manipulation of their production and beer furanone content.

Relationships of Sweetness in Lager to Selected Volatile Congeners

“…Congeners reported to contribute to sweetness include maltol and the 4-hydroxyfuranone derivatives: 4-hydroxy-2,5-dimethyl-3(2H)-furanone (HDMF); 4-hydroxy-2(5)-ethyl-5(2)-methyl-3(2H)-furanone (HEMF); and hydroxymethylfurfural (HMF) 6,7,18 . All are Maillard reaction products formed by reactions between reducing sugars and amino acids during malt kilning and wort boiling 18 .…”

“…All are Maillard reaction products formed by reactions between reducing sugars and amino acids during malt kilning and wort boiling 18 . Caramel-like sweet characters have been ascribed to HDMF, HEMF, and maltol; HMF is considered to have a 'meaty / brothy' note 6,7 . Esters are also thought to contribute to sweetness in aroma and are present in varying concentrations in lager headspaces 1,3,15 .…”

“…An aliquot (2 mL) of filtered aqueous 20 mM DCDB solution was added to 20 mL lager and the mixture incubated at 40°C for 120 min. The DCDMQ formed was then extracted into 3 mL toluene containing 10 µg/mL of nonadecane (C 19 ) as an internal standard using test tubes (50 mL) (method reported to give reproducible results 7 ). Then 1 µL of the toluene layer was chromatographed on 30 m × 0.25 mm of 0.25 µm d.f.…”

Time Intensity Parameters of Sweetness Perceptions in Lager Beers

“…Training can only be successful through loss of individual differences in signatures, which may relate to consumer decisions. Lager sweetness is not from sugars 14,15,27,31 but from a number of volatile congeners 31 and further modelling research could clarify relationships between TI parameters and compositional data from chromatographic analyses 33 .…”

“…Congeners contributing to sweetness in lagers have been explored 14,15,27 but there have been few published reports on sensory perception of the character. We have previously explored bitterness 29 and this study is a continuation of investigations of lager flavour.…”