I remember receiving this (though I honestly don't have a clue as to who sent it ) and hearing rumor of a possible conference proceeding being published. At that time I didn't want to compromise any attempt at publishing the proceeding by posting the notes I had. Well, since the proceedings haven't ever been published, and since loosing this presentation doesn't do anyone any good, I've reproduced the photocopies here as well as I could.
Before we get to the meat of the article, I'd like to put in a few good words for Charlie Finkel of Merchant Du Vin (Importers of Lindemans as well as a host of other beers), and Liberty Malt Supply Co. of Seattle WA. Through their efforts to hold "Homebrew U", the homebrew community is able to benefit from talks such as this. I would also like to thank Dr. Mussche for his effort at presenting in English. Though the notes may not flow well in some places, I commend him and I must say that I doubt I could have done anywhere near as well if I where to try to make such a presentation in French.
--Mike Sharp (msharp@Synopsys.com)
Wild fermentation is not so strange and done all over the world : (see table 1), but unique for the Belgian type of wild fermentation is, that only the wind is helping?
Even with our fruitbeers the wind and the fruits are the only tools to innoculate our wort or young lambic.
Till 800 beermaking was a ladies job, and from the early middle age (about 900) the real brewing as a commerical fact is starting. The monks were the stimulators for quality beers by reinocculation by the previous brew at more or less stable room temperatures; the top fermented beers were born.
About 768 hop was introduced to Europe by the monks and in 1402 the first dark-lager was made by Mr. Naburg in Bavaria. About 1840 a more pale lager was created in Pilsen. It happened by accident, because the malt was bleached by the SO2 and CO from the brown charcoal. The real pale lager was brewed in 1920 in Belgium at the Alken Brewery.
Besides the wild beers, known in Belgium as lambic since 1400, there were also: top fermented beers, bottom fermented beers, red-sour beers, white beers and so on. (Sheet 1 - Our History)
The composition of the raw materials makes the beer a unique broth (wort) for wild inocculation and fermentation.
By law we must use:
(Sheet 2: comparison of raw materials)
The brewing method of lambic is the turbid mash method with the pecularity that the brewer intends to obtain a highly dextrinous wort, more appropriate for sustaining a long fermentation by a mixed flora of microorganisms and leading to the typical lambic flavor. (See Sheet 3 - brewing method)
To avoid the bitter taste of hop in these acid beers, high doses of aged hop are used during the long wort boiling period. After wort boiling, it is cooled overnight in large shallow trays. During this cooling period microorganisms are introduced (Table 2,3), cooled and infected wort is then pumped into wooden casks of 700 liters. The spontaneous fermentation then starts and may last for two years.
(See sheet 4 - evolution of micro flora)
The fermentation is introduced by the development of wort enterobacteria. Their numbers in cooled wort may vary from brewery to brewry, but largely exceed yeast counts. These fastly growing bacteria obtain their maximal concentration (about 10^8 cells/ml) after one week; but they persist only for about one month because of pH lowering and ethanol production.
(Sheet 5 - Evolution of ethanol, pH and ethanol)
The wort enterobacteria are replaced by yeasts responsible for the main or primary alcoholic fermentation. This main fermentation is mainly done by the non-actidione-resistent yeasts (like Saccharomyces species). The real attenuation increases to 50-60% and the pH falls to about 4.0. Ethanol and normal by-products like esters are formed.
The yeast population is a succession of species with increasing fermentative capacity.
Saccharomyces globosus, S. dairensis, S. uvarum, S. bayanus and S. cerevisiae. The primary alcoholic fermentation takes 3-4 months.
The third phase in the lambic fermentation is a lactic acid fermentation by Pediococcus Cerevisiae. The lactic acid increase to 5-6 g/l and the pH falls to pH 3.2. The pediococci dominate the flora from the 3rd to the 8th month.
During or after the lactic acid fermentation, the secondary alcoholic fermentation starts. This results in an increase of the real attenuation to 80%. The concentration of the ethyllactate shows a tenfold increase during this period. The yeast responsible (Sheet 6) for this phase belongs mainly to the species Br. Bruxellensis and Br. Lambicus.
(Sheet 6 - Evolution in ethylacetate and ethyl lactate).
After one year of fermentation, Brettanomyces spp and P. cerevisiae remain in suspension, but drastic changes in composition are no longer observed. The later part of the fermentation must be considered as a maturation during which the characteristic "old lambic flavour" develops.
Table 4: Comparison between Saccharomyces and Brettanomyces yeasts. Pictures 1 and 2 of Saccharomyces and Brettanomyces cells.
Two groups of microorganisms seem important: the actidione- resistant yeasts (Brettanomyces) and the lactic acid bacteria, although the yeasts die after about 10 months. The yeasts at a level of about 10^5 c.f.u./ml, developed during the first month as the counts on the day of bottling were only around 10^2 c.f.u./ml. [c.f.u. is an abbreviation for "colony forming units" -MDS]
Lactic acid bacteria at a level of around 10^6 c.f.u./ml remain consistently present after 5 months. At the day of the bottling their numbers were around 10^2/ml. Acetic acid bacteria disappeared after 3 to 4 months. At the day of the bottling their numbers were around 10^2/ml. Acetic acid bacteria disappeared after 3 to 4 months. Non- actidione resistant yeasts were consistently present during the first 10 months. Their numbers were not much higher than at the time of bottling (10^2/ml). Many of these yeasts were isolated and identified. None was a Saccharomyces, but were of the genera Candida, Torulopsis, Hansenula, Pichia and Cryptococcus. Unexpectedly, the Pediococci, which are the most unconstantly growing organisms after isolation, remain the longest- living organisms in the gueuze.
The best results are with sour-wild cherries; the meat of the cherries is very red-flavoured on a big stone. The fruit is added in the cherries-season (July). Since a 20 years the cherries-beer is made all over the year with single juice from crushed defrozen fruits. The last method gives much more colored, flavoured (like almond) cherries beer.
The beer with the fruits is well-balanced after another 6 months fermentation in the casks but only with sour-dark-red cherries; with a normal cherry-fruit the beer is light pink in color, and the taste- flavour is eaten by the yeast. Here again the Brettanomyces yeast is the most usefull. We obtain a refermented Kriek in the bottle by blending 2/3 of a young cherries-beer with 1/3 of an overyears cherries- beer.
Other fruit beers of lambic brewers are mainly made by addition of the fresh juice to a young lambic. The problem with most of the fruits is the weakness of the flavour and color against the yeast-metabolism. Raspberries color and flavour is completely metabolished by the Brettanomyces yeast. Therefore in an artisanal lambic brewery the fruit beers are made by blending of lambic and fresh single juice before bottling. The maturation takes place in the bottle without fermentation.
Table 5. Substantial composition of gueuze
The combination of an acid taste (pH3.3) with a very dry mouth- feeling (from high tannin-content) makes the beer very drinkable.
The flavor is a combination of alcohols, esters, aldehydes and some hop-terpenoids.
It is strange that a beer with more than 5000ppm acids, over the 500ppm esters and at least 50.000ppm alcohol is so popular and gives the best base for a fruit beer... that's maybe the secret.
Table 1 Fermented foods (beverages) containing mixed and/or wild
[originally this was too wide to fit on the page. I removed columns of "Aspect" and "Use" since they didn't lend much additional information. -MDS]
Product/name Substrates Organisms References BELGIUM Lambic/Gueuze Barley/wheat Enterobacteria, Van Oevelen, Mussche, yeasts, Pediococcus et.al. 1976, 1977 Acid Ales Barley,rice, Saccharomyces corn Lactobacillus CHINA Soy sauce Soybeans/wheat Aspergillus, Young & Wood, 1976 Pediococcus, Saccharomyces EASTERN EUROPE Kefir Milk Yeasts, Lactic bacteria Tea Fungus Tea Leaves, Acetobacter, yeasts Hesseltine, 1965 Sugar INDIA Sonti Rice Rhizopus, Yeasts Hesseltine, 1965 JAPAN Sake Rice Aspergillus, Kodama & Yoshizawa Saccharomyces, Lactic acid bact. MEXICO Pulgue Agave Zymomonas, Yeasts, Lactic acid bact. SUDAN Merissa Sorghum Saccharomyces, Lactic acid bact. U.S.A. Bourbon Maize/Rice/ Lactobacillis delbrueckii, Barley Saccharomyces C.I.S.(U.S.S.R.) Kwass Rye/Barley Yeasts, Hesseltine, 1965 Lactic acid bact. West-Germany Weissbier Wheat,Barley Saccharomyces, Lactic acid bact. South-Africa Kaffir Sorghum,Maize Yeasts, Williamson, 1955 Lactic acid bact.
Yeasts Isolated from brewery air Total percentage outside inside Schizosaccharomyces 0 2 2.25 Kloeckera x (1) 0 3 3.37 Sacchromycodes 1 2 3.37 Sacchomyces (1) 8 18 29.21 Hansenula 0 1 1.12 Torulopsis 6 38 49.44 Candida 1 7 8.99 Brettanomyces (1) 1 1 2.25 ------ ------ TOTAL: 17 72 (1) Mainly during lambic fermentation
Microbiol. species In lambic wort In Ringer solution after 1 night cooling after 1 night infection Enterobacteria 1-50 CFU/ml 3 CFU/L Acetic acid bacteria not present in 100ml not present in 1L Lactic acid bacteria 1-10 CFU/L not found in 1L Total yeasts 10-150 CFU/ml 40 CFU/L Actidione-resistent 10-20 CFU/L 25 CFU/L yeasts
Brettanomyces sp. Saccharomyces sp. Ascospores - + Acid from glucose + - Actidione Resistent + - Ferment: Glucose + + Maltose + + Raffinose - +1/3 Assimil: Glucose + + Maltose + + Raffinose - + Nitrate + -
Traditional Gueuze Filtered Gueuze Lagers Ales BrewA BrewB BrewC BrewA BrewB BrewC Density d20 1.011 1.01 1.01 1.017 1.016 1.014 Tannins ppm 350 375 360 340 335 345 150 210 Ethanol g% 4.95 4.89 4.58 4.71 3.84 4.49 pH 3.34 3.25 3.45 3.2 3.45 3.35 4.2 4 Lactic acid ppm 3434 3000 5277 2071 3510 2107 70-200 70-200 Acetic acid ppm 656 680 1238 1177 580 538 60-140 60-140 Ethyl Acetate ppm 61 72 82 68 34 34 08-20 06-23 Ethyl Lactate ppm 384 437 419 107 188 118 0.1 0.1 1-amyl acetate ppm 0.5 0.6 0.1 1.6 3.1 2.1 1.2-28 0.7-3.3 2,3 Butanediol ppm 716 406 618 318 274 196 10-51 42-128 Remark: Filtered Gueuze: - High content of 1-amylacetate means that the young lambic is blended with some top-fermented beers before filtration Traditional Gueuze: - Typically very high in tannins from hops, ethyllactate, 2,3-butanediol
6000-5500BC Fermented cereal to a kind of beer (sikaru), in Mesopotamia later "shekar" 2500-1500BC Fermented cereals + dads to "tithum" = beer in Egypt 800-1000 Beer at monasteries with hops, cereals, top fermented yeast 1400 Dark lager beer by Naburg, Bavaria (cooling with ice) 1400 Lambic-recipe 1500 Lambic-name 1840 Light dark lager beer in Pilsen (CSR) with paler malt Pasteur and Hansen found yeast cells in the fermentation 1890 Light dark lager beer in Bavaria 1893 Lambic in bottles - gueuze 1920 Light pale lager beer in Belgium (Alken) with pale malt 1930 Kriek - cherry beer 1978 Framboos - respberry beer 1983 Perzik - peaches beer
Lager Lambic a. Raw materials Malt min 50% Malt Adjuncts max 50% Unmalted wheat min 30% as rice, corn, starch Fresh hop preparates Annuated hops as whole hops, pellets, extracts b. Brew-method Decoctie-method Turbid mash method Infusion-method c. Boiling-copper 90 minutes 5-6 hours d. Cooling Aseptic - fast 8C Coolship open under the wind e. Inocculation Pure yeast amount From the brewery air after propagation f. Fermentation-maturation +- 8C - 6 days 6 months and 24 months +- 2C - 1 month
Malt Wheat Milling Milling 500L at 55C 100 kg | | | | | +-------------Mash at 45C--------------+ | | <-------- addition H2O of 90C | Mash at 52C | Taking of <----------+ turbid mash | | <-------- addition H2O of 90C | Mash at 65C | Taking of <----------+ turbid mash | | <-------- addition H2O of 90C | Mash at 72C | Taking of <----------+ turbid mash | | | Heating to 85C ------->+ | Filtration at 78C | | <-------- wash with H2O of 95C | (in lauter tun) | 5-6h boiling <-------- annuated hops 3kg/500L | Hop - sieve - filter in coolship Cooling and air-inocculation | Fermentation in wooden barrels or wood-coated tanks
Sheet 5 - Evolution in attenuation, ethanol, and pH during lambic fermentation
Sheet 6 - Evolution in concentration of ethyllactate and ethylacetate during lambic fermentation
Sheet 7 - Microbiological profile of gueuze bottle fermentation
[sorry folks, I can't do these graphs in ASCII-graphics -MDS]
Refermented in the bottle Filtered (Brut, Fond, Artisanal) Blend of 2 parts of young lambic 1 part of old lambic | | | +sugar | filtrated | +CO2 | | Bottled Bottled | | Refermentation and | maturation in the | bottles | | | Sales Sales
with fruit with fresh single with concentrates juice and flavours (artisanal) (artisanal) (industrial) young lambic young lambic young beer (6 months old) (6 to 12 months old) in casks in casks +125kg +25 to 35% +aromas sour-cherries single juice and concentrates per 600L lambic | | or | | +275kg | | raspberries | | per 600L lambic | | or | | +250kg peaches | | per 600L lambic | | | | | Fermantation | | | | | Bottling Filtration+ Filtration+ | bottling bottling or refermentation | | in bottle | | | Bottling | or filtration before maturation | bottling | | | | | Sales Sales Sales Remark: 1. and 2. are from real lambic breweries like Lindemans[there are also 6 photomicrographs of various organisms, but I'm sure not going to reproduce these in ASCII graphics -MDS]