Monophenols in beer. by Femke Sterckx. XIVth Chair J. De Clerck 14 September 2012

Transcription

1 Monophenols in beer by Femke Sterckx XIVth Chair J. De Clerck 14 September 2012

2 Monophenols in beer: overview Vanilla flavour in beer and relation with monophenols Flavour-activity of monophenols thresholds, interaction and effect on beer flavour How monophenols end up in beer origin from raw materials and wood aging

3 Monophenols in beer: overview Vanilla flavour in beer and relation with monophenols Flavour-activity of monophenols thresholds, interaction and effect on beer flavour How monophenols end up in beer origin from raw materials and wood aging

4 Vanilla flavour is unique for each individual Tasting sessions 10 Belgian beers, 6 individuals Vanilla descriptors scored in all beers from 0 to 8

5 Vanilla flavour is unique for each individual Tasting sessions 10 Belgian beers, 6 individuals Vanilla descriptors scored in all beers from 0 to 8 creaminess Differences appear between individual tasters warming chemical Taster 1 vanilla smoky Average cooked millk cooked rice 3 6 spicy Taster 2

6 Monophenols might be responsible for vanilla flavour OH R 3 R 2 R 1 guaiacols phenols OH O Monophenols as flavour compounds Widely present in foods and beverages In wines and spirits vanilla, spicy flavours 4-vinylguaiacol in beer R 3 O OH R R 1 R 2 carbonyls Screening of Belgian specialty beers 25 different monophenols H OH Identification in beer Various functional groups O salicylaldehyde

7 Monophenols in beer: overview Vanilla flavour in beer and relation with monophenols Flavour-activity of monophenols Flavour thresholds, Interactions between monophenols Effect on over-all beer flavour How monophenols end up in beer origin from raw materials and wood aging

8 Many monophenols have low individual flavour potential Thresholds of difference Smallest difference in concentration that can be noticed 11 compounds, from 3 ppb to 22 ppm Concentrations in beer fairly low Flavour units < 0.2 No pronounced flavour effect Changing the flavour balance of the tested lager beer Slightly softer, sweet, vanilla, spicy notes

9 Monophenols show predominantly positive flavour interactions Mixture thresholds Addition of 2 compounds together Synergy <> Antagonism Mechanism of interaction similar structure remains unclear similar flavour Mostly positive interactions 9 combinations of monophenols tested: 8 positive, up to very synergetic, 1 antagonistic

10 Recombination experiments confirm influence on beer flavour Recombinations of Belgian beers Difference in concentrations added to lager beer 8 and 4 monophenols added Triangle tests showed significant difference 7 and 6 out of 7 correct answers Influence on flavour Even at very low concentrations

11 Together monophenols impart beer with vanilla, spicy flavours creaminess warming vanilla monophenols cooked milk cooked rice chemical smoky spicy 8 monophenols

12 Monophenols in beer: overview Vanilla flavour in beer and relation with monophenols Flavour-activity of monophenols thresholds, interaction and effect on beer flavour How monophenols end up in beer origin from plant materials use of different cereals for brewing effect of wood aging

13 Monophenols originate from plant material Phenylpropanoid pathway Starting from L-phenylalanine Role in plant defence? Precursors of monophenols Lignin Hydroxycinnamic acids Glycosidically bound Occurrence in plants Naturally in broad variety of plants (grapes, cereals, wood ) Widely present in foods and beverages

14 Monophenols in beer: overview Vanilla flavour in beer and relation with monophenols Flavour-activity of monophenols thresholds, interaction and effect on beer flavour How monophenols end up in beer origin from plant materials use of different raw materials for brewing effect of wood aging

15 Mashing is the first step of the brewing process mashing lautering boiling

16 Specialty malts are often used mashing lautering boiling

17 Cereal adjuncts partly replace malt mashing lautering boiling

18 Mashing trials showed variation in monophenol content Lab mashing trials determining extractable amount of monophenols for 1 hour at C, ph Specialty barley malts 1 pilsner malt, 2 caramel malts, 1 roasted malt Cereal adjuncts barley, rice and maize flakes (processed) rice and maize grits (broken grains)

19 Monophenol content differed between specialty barley malts Pilsner malt Caramunich Caraaroma Carafa Factor-2 (16%, 32%)

20 Monophenol content was correlated with heat treatment of specialty malts B

21 Monophenol content varied between cereal adjuncts Maize flakes Maize grits Rice flakes Pilsner malt Barley flakes Rice grits Rice flakes Maize

22 Monophenol content was higher in maize and rice flakes B

23 Choice of raw materials influences monophenol content of the wort Increase with specialty malts Most monophenols related to intensity of heat treatment Use of cereal adjuncts Maize and rice flakes richer in monophenols Influence on beer flavour? Guaiacol, vanillin, 4-vinylguaiacol, eugenol

24 Monophenols in beer: overview Vanilla flavour in beer and relation with monophenols Flavour-activity of monophenols thresholds, interaction and effect on beer flavour How monophenols end up in beer origin from plant materials use of different cereals for brewing effect of wood aging

25 Overview of the brewing process

26 Overview of the brewing process cooling fermentation lagering filtration

27 Wood aging is applied for some specialty beers cooling fermentation wood aging filtration

28 Addition of oak chips leads to increased monophenol concentrations Oak chips added to bottled beer American & French oak chips, medium and heavy toasted stored up to 60 days (20 C) Typical wood aged flavours great increase in vanilla, smoky, woody, spicy Increase of monophenols almoust all monophenols extracted from wood into beer

29 Toasting level influences amount of monophenols Heavy toasted Medium toasted Ref Medium toasted Heavy toasted

30 Different oak origins lead to differences in monophenols American oak French oak Ref Amercian oak French oak

31 Monophenols can be associated with typical wood aged flavours 1 0,8 0,6 0,4 0,2 0-0,2-0,4-0,6-0,8-1 eugenol thymol salicylaldehyde 4-ethylphenol wood_aging 4-hydroxybenzaldehyde phenolic 4-vinylguaiacol spicy burned smoky coconut vanillin sweet caramel creamy methyl_vanillate vanilla guaiacol avetovanillone 4-ethylguaiacol syringaldehyde acetosyringone -1-0,5 0 0,5 1 Factor-1 (43%, 22%) Woody Vanilla

32 Wood aging parameters influence monophenol content Various parameters evaluated amount of chips, temperature, ph, ethanol content, oxygen in buffer solutions (stored for 30 days) Wood addition during beer lagering after main fermentation - with yeast still present lagered at 0, 4 or 20 C Enzymatic release from wood β glucosidase released 3 monophenols

33 Monophenols in beer: review Vanilla flavour present in beer probably related with monophenols Monophenols are flavour-active thresholds, interaction and effect on beer flavour How monophenols end up in beer origin from raw materials and wood aging

34 General conclusions Raw materials determine monophenol concentrations use of special malts or adjuncts might affect beer flavour Wood aging results in increased monophenol concentrations & imparts beer with woody, vanilla-like, spicy flavours Monophenols can jointly enrich beer flavour with spicy, vanilla-like flavour notes

35 Acknowledgements Prof. F. Delvaux my promotor the CMBS for all the help and the good time IWT Vlaanderen for financial support

36 Monophenols in beer by Femke Sterckx XIVth Chair J. De Clerck 14 September 2012