Chair J. De Clerck IV Post Fermentation technologies in Special Beer productions Bottle conditioning: some side implications
Chair J. De Clerck XIV, september 14 Bottle conditioning: some side implications Yeast a. Screening and selection b. Harvesting/propagation c. Dosage Bottle conditioning a) Beer warmer b) Cellar conditions c) Evolution of aroma compounds Various side implications
Screening and selection for bottle conditioning Standard lab fermentation conditions Use of ultimate receiving/final wort Variables a) Fermentation temperature b) Fermentation pressure c) Inoculation rate d) Oxygenation e) Alcohol% at inoculation (*) Measuring a) Fermentation speed b) Higher alcohols and esters c) Sulphur compounds & vicinal diketones d) Yeast concentration e) Yeast viability f) Yeast vitality
Screening and selection for bottle conditioning Standard lab refermentation conditions Use of ultimate receiving beer Variables a) Time of harvest (growth phase, stationary phase, or at specific ADF) b) Pre-oxygenation c) Refermentation temperature d) Inoculation rate Measuring a) Extract evolution in time b) Evolution higher alcohols and esters (at different storage temperatures 0/10/20 C) c) Sulphur compounds, acetaldehyde & vicinal diketones d) Yeast concentration e) Yeast viability f) Yeast vitality
Yeast harvesting/propagation Bottle conditioning yeast origin, different possiblities a) Top harvest of cylindro-conical fermentation - Fillling rate >80% - Fixed connection to unique yeast receiving tank - Slight overpressure (0.10 bar) Closing CO2-exhaust Automatic opening one-way valve, situated in top yeast layer CO2 + yeast evacuation - Receiving tank on load cells - Harvesting parameters: Yeast growth phase or ADF # kg s / fermentation (up to 3000 kg / 1000 hl) - Immediate cooling of harvested yeast - Implication: when harvesting in early stage, need of equal volume without harvest to reach end attenuation We use it as option I
a) Top harvest
b. Yeast harvesting/propagation
Yeast harvesting/propagation Bottle conditioning yeast origin, different possiblities b) Freshly propagated yeast Size implications - 500.000 hl/yr at inoculation rate of 2 mio cells/ml - Max. propagation concentration: strain dependant (150-400 mio cells/ml) - Need of 20 40 hl / day Side impact - Source of fermentable sugars (ex. Dilution rate of 1/100 at 8 Plato remaining fermentable extract 0.08 P which equals 0.4 g CO2/l.) - Increase in turbidity We use it as option II
Yeast harvesting/propagation Bottle conditioning yeast origin, different possiblities b) Freshly propagated yeast Size implications - 500.000 hl/yr at inoculation rate of 2 mio cells/ml - Max. propagation concentration: strain dependant (150-400 mio cells/ml) - Need of 20 40 hl / day Side impact - Source of fermentable sugars (ex. Dilution rate of 1/100 at 8 Plato remaining extract 0.08 P which equals 0.4 g CO2/l.) - Increase in turbidity We use it as option II
Yeast harvesting/propagation Bottle conditioning yeast origin, different possiblities c) other. Centrifugation - Shear stress - Difficult planning and organisation, if time of harvest needs to be respected - Time- and energy consuming - Investments (centrifuge, yeast cooler, ) - Increases sanitary complexity =We use it as option III Cone-yeast Dried yeast Fermenting beer
Yeast harvesting/propagation Viability: measure of living cells Test: methylene blue Problems: reliability and no strict relation with vitality Vitality: measure of physiological state of viable cell population Test: Acidification Power Test
Yeast harvesting/propagation Acidification Power Test ph drop of a glucose solution with suspended yeast cells serves as an indicator of the physical condition of the yeast Optimised Acidification Power Test WAP (water acidification power) GAP (glucose acidification power) GIPE = GAP -WAP (glucose inducedproton efflux) is the ability of cells to use extracellular reserves is a useful biomarker for the evaluation of yeast quality
Yeast harvesting/propagation Evolution of GIPE parameters due to different exposure times at 8 % alcohol stress 1 0,9 0,8 0,7 0,6 0,5 0,4 freshly propagated 9th generation 0,3 0,2 0,1 0 0h 2h 4h 6h
Yeast dosage Proportional and dynamic dosing Working concentration: 150 500 mio cells/ml Dilution in deaerated and demineralised water In-line dosing towards filler (no buffer tank) Accurate dosing necessary Continuous measurement: - viable-yeast concentration in dosing tank -beer flow - yeast dosing flow i. Double measurement (mass and flow) ii. Maximal variation of 5% between mass and flow measurement -turbidity prior and after dosing (as a check; no master) Yeast dosing via positive displacement pump (max independence of pressure variations)
Proportional and dynamic dosing
Beer heating Faster and more reliable start of refermentation In line warming up beer flow to 18-20 C No direct steam/beer contact: necessary secondary water-circuit 2 plate heat exchangers Maximal circulation flow, for fast reaction time Strict control of beer temperature (+/- 10% relative to setpoint allowed for 5 sec s)
Beer heating Faster and more reliable refermentation 9 Influence of bottling temperature g/l CO2 vsdaysin warm cellar 8,5 8 7,5 7 6,5 6 5,5 5 4,5 4 0 2 4 6 8 10 12 14 16 4 C 8 C 12 C 20 C
Cellar conditions Classic bottle conditioning setpoints: - Carbonation start 3-6 g CO2/l. - Carbonation target 5-9 g CO2/l. - Sugar addition 0.4 1.0 Plato - Temperature 18-24 C - Time 1-3 weeks Strict temperature control necessary - Conventional air heating blowers - Floor heating Control of relative humidity - Below 60% relative - Gives possiblity to cool down cellars, under extreme climatologic conditions Use of non photo-oxidative lighting Transfer, when CO2-target is reached, to cooled cellars (8-10 C) (warm/cold cellars: energetic closed cycle) Storage untill moment of sale
Aroma evolution Various tests carried out Evolution of higher alcohols, sepcificaldehydes, vicinal diketones, specific sulphurcompounds, in function of - Selected yeast strain - Time of harvest - Pre-oxygenation - Flash pasteurised/ non pasteurised - Storage time - Storage temperature - Inoculation rate -. Focus on esters, since very important aroma-active compounds, derived from yeast metabolism
Aroma evolution Screening of fermentation and lagering on secretion of ester-degrading enzymes - top fermented beer (O.G. 17.0 P) - Saccharomyces cerevisiae cerevisiae CMB212 - fermentation: 7 days, 24 C - lagering: 7 days, 0 C - induced autolysis: 36 days, 28 C - samples were filtered and bottled on days: - 1-7 (fermentation), 8-15 (lagering), 30 and 51 (induced autolysis) - corrections: ph, ethanol % (v/v), isoamyl acetate, isoamyl alcohols, acetic acid
Aroma evolution 120 isoamyl acetate: % initial concentration after storage at 24 C 100 80 60 40 20 0 0 1 2 3 4 5 6 time (months) day 0 day 1 day 7 day 11 day 14 day 51
Aroma evolution Influence of inoculation rate on degradation of important aroma-compounds - top fermented beer (O.G. 17.0 P) - Saccharomyces cerevisiae cerevisiae CMB212 - fermentation: 7 days, 24 C - lagering: 7 days, 0 C - flash pasteurised prior to bottle conditioning - Bottle conditioning & storage - CMB 212 - Variable inoculation rates (0 0.5 1.0 2.0 5.0 10.0 20.0 miocells/ml) - 0.6 P fermentable extract - 24 C, 6 months
Aroma evolution 100 isoamyl acetate: % inital value after 6 months at 24 C 90 80 70 60 50 0 5 10 15 20 25 inoculation rate (x 10E6 cells/ml)
Aroma evolution Influence of yeast strain on degradation of important aroma-compounds - top fermented beer (O.G. 17.0 P) - Saccharomyces cerevisiae cerevisiae CMB64B, 212, 214 - fermentation: 7 days, 24 C - lagering: 7 days, 0 C - Flash pasteurised prior to bottle conditioning - Bottle conditioning & storage - CMB 64B, 212. 214 - inoculation rate (2.0 mio cells/ml) - 0.6 P fermentable extract - 24 C, 2 weeks
Aroma evolution 110 100 isoamyl acetate: % initial value 90 80 70 60 50 0 1 2 3 4 5 6 time (months) pasteurised pasteurised + yeast CMB 212 pasteurised + yeast CMB 64B pasteurised + yeast CMB 214
Aroma evolution Influence of storage temperature on degradation of important aroma-compounds - top fermented beer (O.G. 17.0 P) - Saccharomyces cerevisiae cerevisiae CMB214 - fermentation: 7 days, 24 C - lagering: 7 days, 0 C - Flash pasteurised prior to bottle conditioning - Bottle conditioning & storage - CMB 64B, 212. 214 - inoculation rate (2.0 mio cells/ml) - 0.6 P fermentable extract - 24 C, 2 weeks - Subsequent storage for 6 months at either 0 C or 24 C
Aroma evolution 110 100 isoamyl acetate: % initial value 90 80 70 60 50 0 2 4 6 8 time (months) 0 C 0 C + yeast 24 C 24 C + yeast
Aroma evolution Influence of pasteurisation on degradation of important aroma-compounds - top fermented beer (O.G. 17.0 P) - Saccharomyces cerevisiae cerevisiae CMB214 - fermentation: 7 days, 24 C - lagering: 7 days, 0 C - Flash pasteurised prior to bottle conditioning - Bottle conditioning & storage - CMB212 - inoculation rate (2.0 mio cells/ml) - 0.6 P fermentable extract - 24 C, 2 weeks - Subsequent storage for 6 months at 20 C
Aroma evolution isoamyl acetate: % initial value 110 100 90 80 70 60 50 40 0 1 2 3 4 5 6 time (months) pasteurised not pasteurised pasteurised + yeast not pasteurised + yeast
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