Monday, July 24, 2017

White Beers of Northern France

About a year ago I posted a brief bit of information about bières blanche from northern France on the blog's facebook page (here and here). Thanks to a friend in Brussels with a good library of historic texts, I was able to locate a bit more information about these beers. This post expands on those initial FB posts with the additional info that I've tracked down. But there is still a long way to go to understand these beers, and I'll continue to look for more sources.

The Nord region of Northern France was an active brewing center around 1900. At this time, breweries in the region were still producing traditional beers of top fermentation. The influence of imported lagers was shifting brewing elsewhere in the country toward lager production. Unfortunately, while traditional beers could still be found in the Lille and Dunkirk areas, they were also in a period of decline here. With WWI coming and the state of brewing in the region already in a tricky spot, the region saw large changes for brewing in a rather short amount of time. I've written about biere of the region in these two posts here (mainly on mashing) and here (mainly on WWI).

Perhaps not a brewery making a blanche, but I wanted a photo generally related
to historic French brewing. From the breweriana collection of D. Thiriez.
So back to the beers of the Nord. Most of us have probably heard of one of these traditional beers - bière de garde (note that bière de garde in 1900 was different from the modern versions) - but other beers were made in the region as well. And I haven't seen much mention of these other beers. While looking for information about French bière de garde about a year ago, I found mention of a bière blanche. I hadn't heard of this beer before and it interested me, but there was very little info to go on in that brief mention. With this new source I'm starting to get a bit of a better picture about this beer and wanted to put up what I know at this point.

Of course, as with other posts on historic brewing, the same caveats apply - namely that this is a small snapshot of the beer (as the beer likely changed over time as well as among different producers) and this understanding is limited to the info given in a few sources.

Blanche de Cambrai
This discussion draws from two main sources - Petit Journal du Brasseur (1910) and Moreau and Levy (1905). The both refer to blanche in general and the latter specifies a beer called Blanche de Cambrai. In the modern world, this latter name applies to a distinct beer made from one brewery. But historically it was a style of beer brewed by many brewers in the region. The same thing - where a style turns into the product of only one brewery - can be seen elsewhere in Europe (e.g. Grisette and Hoegaarden). I'm not sure if the brewery making Blanche de Cambrai holds a trademark on the name, as is the case with the other two examples. When discussing Blanche de Cambrai for the rest of this post, I am referring to the historic style rather than the modern brand name.

Historic Blanche de Cambrai mostly matches the general description of blanche in PJB, but there is a notable difference in attenuation. On the whole, these white beers don't seem very common but they were produced at multiple breweries in the early 1900s. They are noted as having a short boil or possibly none at all (though in the latter case beer would be held at boiling temps, so maybe more of a simmer than no boil in the modern sense). For the time this is quite unusual as beers could easily have a multi-hour boil, possibly approaching 8-12 hours or more.

The blanche beers seem to be of moderate gravity (~1.035-1.040) and were lightly acidic. Some of the parameters of the beers are shown below, along with comparison to other blanche beers and acidic beers, both modern and from ~1900. These northern French white beers are described as having a good hop aroma. The attenuation was either moderate or high. It seems the beers were consumed around 3-4 weeks from brew day (or possibly a week or two older).

Parameters of northern French Blanche and historic and modern Belgian and German acidic beers.
The grain used is described as being as pale as possible. Moreau and Levy note that an ordinary brown beer was brewed at the same time and from the same grist as this white beer (this brown beer is not completely straightforward, but that is a topic for a later post). Unlike bière de garde, which would use a form of turbid mashing, it seems that the white beer is produced by infusion mashing. About 25-30 kg of grain is used for 100 L. I interpret this to mean 100 L of each blanche and brown beer (it isn't explicitly clear, but given context and expected extract this seems necessary). There is no discussion of grain breakdown (and actually no mention of wheat by name in either source). The barley used in this region was mostly a winter 6 row. There is also general mention of brewers in the region using a bit of straw to help with the lautering, which agrees with other beers brewed with wheat at the time in Belgium such as lambic and grisette (as discussed here). Moreau and Levy note that some brewers use rice.

Initially a cool infusion is made and the mash is quickly drained. This is effectively a rinsing, and is done to remove some of the color of the grain. This rinse is held to the side and will be added the the brown beer. Then the mash is raised to a low saccharification temp, where a long rest is performed (~1 hour of stirring followed by 75 min of rest). After this the mash is drained and first runnings become the white beer. Note however that the white beer is not especially strong. The remaining runnings (and the cool rinse) going to the brown beer.

The white beer portion is boiled for up to about an hour (though Moreau and Levy note that some brewers only hold the wort near a boiling point, in agreement with PJB). Hops are only added in the cooling tuns or at the end of boiling (preferably in the cooling tun), but the hopping rate is fairly high at ~9-10 g/L (compare with grisette and saison/Belgian bières de garde here and with lambic here). Moreau and Levy note that some brewers spiced their beers with coriander, star anise or iris.

The beers are fermented with ale yeast (which, given the time means a mixed culture of bacteria and/or other yeasts such as Brettanomyces). Although the hopping was high, the hops were not boiled and some acidity is able to develop. The beer was bottled (with priming sugar) after a couple weeks and was carbonated a couple days later.

Final Thoughts
All this seems like an interesting beer - light acidity, low gravity (in the modern sense) and hop flavor but not so much bitterness. It sounds like it would be pretty refreshing. The brewing process described in Moreau and Levy seems pretty unique and I wonder if other brewers in the region followed a different process for their beers. And/or if similar process shows up for other beers elsewhere. Overall I think this is a cool, if uncommon, component of northern French beers from ~1900. And hopefully I can find some more info elsewhere about these beers.

Sources for the text:
Petit Journal du Brasseur, 1910
Traité Complet de la Fabrication des Bières (1905), Moreau & Levy.

Tuesday, July 11, 2017

Lambic attenuation and carbohydrate composition

Here are some data on the carbohydrate composition of lambic and how this composition is modified throughout lambic attenuation. The data come from the PhD thesis of H.M. Chandana Shantha Kumara (KU Leuven, Verachtert Group), which focuses on lambic attenuation and identifying the key players responsible for causing the high attenuation of lambic relative to most normal beer. There is some great work in the thesis, especially in showing the microbes and microbe combinations responsible for the attenuation and characterizing the enzymes driving this. Parts of this thesis have been published as scientific papers (here, on identifying super-attenuating microbes, as well as these two papers on characterizing and localizing glucosidases in brett and in Lactobacillus) but I have only seen this specific carbohydrate data in the thesis itself.

The thesis.
Many people likely heard something to the effect of "lambic uses a turbid mash, which produces longer chain carbohydrates that help to provide food for organisms like brett over the long fermentation". While I believe this to be true and it makes logical sense, there aren't a lot of studies (other than this one) that provide clear evidence to how that happens. And this is a fairly basic statement. I'm interested in more specifics about turbid mashing so I've been thinking about questions to look into and have been looking for info that might provide a bit more detail. For example, different lambic producers are using different turbid mash schedules. And there were many other schedules used historically (and not always to provide a food source for microbes over a long time period as is the case with lambic). I've written about a couple other schedules in these posts on French bière de garde and low-gravity Belgian beers. So how much do the variations in specific schedules change the final beer? And how much do the variations in turbid mashing change the fermentability of the wort to more normal brewing yeasts? And then what classes of 'unfermentable' material that is carried into the wort from turbid mashing is accessible to the yeasts and bacteria active at 1-2 years in fermenting lambic? This PhD thesis provides some info on that last point.

Sampling and the Data

Samples were collected at one brewery from barrels of different ages. My interpretation from the text is that all the samples were collected at one time point and therefore that they are from different brew days and brewing seasons. But this could be a misinterpretation as it isn’t completely clear from the text. If my interpretation is correct, then some of the variability over fermentation could be due to differences in the starting points. However, since the samples are all coming from the same brewery using (presumably) one consistent process, the batch-to-batch variability is likely to be smaller than many of the general trends.

This post shows a couple figures I produced with data presented in chapter 3 of the thesis on carbohydrate composition from lambic of different gravities. The carbohydrates are broken into groups depending on how many individual sugar units the carbohydrate is composed of. So this ranges from a simple 1 unit sugar like glucose, 2 unit sugars like maltose, up to carbohydrates made up of more than 100 glucose units. This size class breakdown will be the focus of the following discussion.

Composition of wort

To begin with, I want to say something about the wort before fermentation. The specifics of the turbid mash schedule aren't supplied in the thesis and the brewery is not named. One could infer the brewery based on the data and other info in the thesis but I don't think that is much of a priority given the small amount of information out there about turbid mashing.

The composition of carbohydrates as a percentage of the total (by mass) is shown in the figure at right. As with other mashing procedures, the composition is dominated by simpler carbohydrates (1-3 sugar units). And the two smallest groups account for ~80%. But I think it is interesting to note that with this turbid mashed wort, the next largest component is the longest sugar chain grouping. These results are by mass rather than by number of molecules, so it is fewer but larger molecules in this class compared to other classes. But still, in terms of the total number of sugar units present in lambic wort, the third largest fraction is the biggest molecules.

I should also note here that the OG of the wort isn’t specified, but I am assuming it is around 13° P as this is where all the standard lambic OG data I’ve seen falls (± ~1° P).

Carbohydrates during attenuation

The initial half of fermentation (by gravity, not time) is accomplished by fermentation of the smaller chain sugars (<3 and 3-6 units), with no appreciable decrease in the longer chain carbohydrates. This makes sense given the microbial start of lambic fermentation – enterobacteria (in breweries not acidifying wort) and select yeasts (e.g. Kloeckera/Hanseniaspora) that utilize only very simple sugars (frequently only glucose) followed by Saccharomyces. These organisms can’t access the longer chain molecules that remain generally unchanged in the first 50% of attenuation.

Carbohydrate composition of fermenting lambic with a full y-axis scale at left and a reduced scale at right.

By the time attenuation reaches ~75-80%, the >185 and the 30-61 unit size classes decrease, showing that the microbes responsible for the high attenuation of lambic have started to work on these. Interestingly, at this point, the 6-30 unit class concentration increases and the carbohydrate concentration of this class does not drop below its initial level for the remainder of fermentation. The persistence of this intermediate class is a pretty novel finding. Dr. Shantha Kumara interprets this as the larger size classes being first cleaved by endo-glucosidases (enzymes acting in the middle of the molecules) to smaller sized molecules including the 6-30 unit range. These smaller ranges are then processed by the cells (either extracellularly and then fermented or internalized directly). So the large carbohydrates are made available by first being broken down extracellularly, leading to a net 6-30 unit carbohydrate production in the lambic, followed by a consistently elevated (though decreasing) 6-30 unit class throughout fermentation.

If this all sounds too complicated, you can picture the different carbohydrate pools as buckets of water with holes in the bottom. Water is draining from the buckets through these holes (carbohydrates are broken down into smaller molecules and/or fermented). For the 6-30 unit size class, you are also adding water (the larger molecules are broken down into 6-30 unit-sized carbohydrates) such that the total level of water in this bucket is rising even though some is still draining out. Eventually you reach a point where you are adding the water more slowly because there is not much left to add (the large size classes have fewer molecules to be broken down to the 6-30 size class) such that the water level in the 6-30 unit bucket can fall again.

Percentage of different carbohydrate size classes in fermenting lambic.
As the lambic reaches final gravity (in this case testing stopped at 1° P, though note that many lambics don’t finish this low), the two largest remaining fractions are the 6-30 unit and the 3-6 unit carbohydrates. I found this quite surprising as I would have expected the more simple molecules to be processed more easily. So perhaps there is still a bit of fermentation going on at this point. Either way, the 6-30 unit class is maintained in appreciable concentration throughout the fermentation while larger molecules are more completely used up. The result, in final or near final gravity lambic, is that the residual carbohydrates are dominated by 3-30 unit carbohydrates while the shorter and longer chain molecules are more completely removed.

The same trend can be seen in the data when looking at the relative carbohydrate composition, where the percentage of the 6-30 unit class increases from ~1/2 attenuation onward and the percentage of the 3-6 unit group remains roughly constant or rises slightly. So at the final gravity point measured here (1° P) these two size classes are the most prominent. In contrast to this, there are basically no carbohydrates left in the 30-185 size classes. The >185 size class counts for a similar percentage in wort as in the final lambic, so there is still something left in this class at the end of these measurements. But the non-normalized data show that there was clear removal of this size fraction during fermentation.

 Thoughts for the future

This study did a great job of showing how lambic wort from one producer using one turbid mash schedule was attenuated over the course of fermentation. But I would be interested to know how this might differ with other producers. What if a different turbid mash schedules produced more long chain carbohydrates? Would this influence the FG? We know that a good number of lambics do not attenuate as far as 1° P, and this is driven by microbes and/or hot side process. The degree to which the microbes in this study were able to access the longest chain carbohydrates suggests that mashing to produce even more of this size class would not result in much of a change in the FG. And therefore that the differences in FGs among different lambics might be due in large part to the capabilities of the different microbes. This interpretation fits with other lambic attenuation data that I’ve seen (though expanding on that is a topic for another post). Additionally, if this were the case, it would highlight the inter-producer diversity of lambic microbes.

None of the above discussion of how different turbid mash procedures may influence beer addresses flavor production. Of course there is the flavor of the wort, which one might assume could vary by different mashing process given that turbid mashed wort tastes different from infusion mashed wort. But there might also be differences in microbial flavor development if the composition of more complex molecules was altered. So there are still plenty of questions to address here.

Finally, I’m interested in more info on turbid mashes compared to conventional mashing. There is unfortunately not quantitative data in this thesis comparing the carbohydrate composition of lambic wort to normal beer wort. But qualitatively, there is a figure showing that lambic has higher levels of carbohydrates with 4 and more sugar units than lager beer. This is especially the case for longer chain compounds that likely have tens to hundreds of sugar units. That is unsurprising, but it would be interesting to have a more quantitative measure to compare. I suspect info like this is out there somewhere and maybe I'll track some down and work it into an update of this.