As I was kegging and carbonating the marzen it occurred to me that maybe it would be worthwhile to filter and keg my lagers following fermentation but before laagering. Whether dumping trube or transferring to secondary, this seems to make sense because it will remove almost all remaining yeast and potentially some DMS. The beer could then lager the perquisite 3-4 weeks and be all ready to go when this period has completed.

Part of the reason for the laagering period is to eliminate some of the off flavors caused by the yeast and DMS, so this really makes sense to me. I posted on the beer forum, so lets see what the community thinks.

Any thoughts from readers?

I need to do the starter soon for the Märzen on Saturday, but was still a little unsure about some of the details. I know that lagers generally take more yeast and thus require a bigger started, but it's always been unclear to me what the proper temperature is for a lager starter. Ale starters are simple because they are fermented at the temperature of the brew or a little warmer. Lagers are usually fermented at much lower temperatures, so it's not clear to me whether the starter should be done at a lower temperature too.

To try and address some of my questions I posted to my favorite homebrew forum to try and get some answers. I am going to copy in the main points below, but you can find the full post here:

Thread: Lager Starter Temperature
I'm going to do my second lager on Saturday and I was wondering what temperature to use for the starter?
Typically with an ale started I would use the range used for the beer (e.g. 68-75), but does it make sense to do the same for a lager?
Should I keep the temp of the lager down around fermentation temperature of 50 degrees F or does it make more sense to do it up around 70 degrees?
I imagine whatever temperature promotes the creation of new healthy yeast is best, I just don't know what that temp is....

Response from menschmaschine:
At this point, I'd do it at room temp (68-70ish), let it ferment completely, put in the fridge 48 hours before brewing to let the yeast settle, and decant the starter beer before pitching.
Some recommend doing lager starters at the same temps as primary. The two reasons for this are so that fruity starter beer isn't created and so the yeast are used to fermenting at 50-ish and they don't have to make the adjustment when pitched to the wort. But these types of starters need to be started 7-10 days in advance. Fermenting starters for lagers at room temp isn't that big of a deal as long as you decant off the starter beer. The yeast may produce some byproducts while adjusting to lower fermentation temps, but this may or may not be noticeable in the final beer.

My followup:
Interesting that your suggsting 7-10 days, I've never heard that before. I usually do my ale starter the Thursday before I brew, which I guess would be two days before pitching. What's the reason for giving the cold lager starter so much time? I mean I understand that lagers take longer because there colder, but 7-10 days is 3.5-5 times longer that I would do for an ale.

Response from menschmaschine:
Lager starters are typically 2 to 4 times as big as ale starters and at those low temps, it takes longer to ferment. This timeframe also allows for the potential to put it in the low to mid 30s a couple days before pitching to settle the yeast and decant off the starter beer.

My followup:
Ahhh, ok. so 5-8 days of yeast growth in the starter and 2 days for the yeast to flocculate for decanting, makes sense. Guess I better do the starter tonight at ale temps so my yeast has time to flocculate.

Response from soperbrew:
A search of this forum for lager starters will provide lots of results. From the information I've gathered here, I've done my lager starters at room temp. 2 or 3 days before use. Then crash them in the fridge for at least a day prior to using. I'll decant the beer off the yeast prior to pitching. I also pitch at fermentation temp. (around 50F). The way I do this is to put the starter container with the yeast in the chiller next to the wort & let them both reach desired fermentation temp. prior to pitching.

A question I never would have considered until reading the Wild Brews book (see review post). It turns out that one of the properties of Brettanomyces that makes it super attenuating (near 100%) is its beta-glucosidase component. In general terms, glucosidase describes a type of enzyme that breaks apart sugars at glucose chains during exposure to water (hydrolysis). Glucosidase is the general term for the specific enzymes that break down sacharrides and disacharrides. For example, maltase will break apart the dissacharide maltose and sucrase will break apart sucrose and fructose.

Beano is often used by homebrewers for the purpose of correcting a stuck fermentation. Specifically what it does is break down the complex unfermentable sugars found in your wort. The reason for this is because the primary component of Beano is alpha galactosidase, and it's primary function is to break down polysacharrides and oligosaccharides in your intestines. Of course in your wort it will do the same thing. It's important to note that many types of dextrins (such as malto dextrin) are in fact Polysacharrides, which makes sense when you know that much of the unfermentable sugars in wort are likely to be dextrins.

It would be interesting to do some further analysis of each of these components to see exactly which sugars they break apart and how they break them apart. This seems important to me because I would expect different flavor compounds from yeast fermentation depending on the fermented sugar is gluscose, sucrose, fructose, galactose, lactose, or some other fermentable sugar.