"Meet the brewer that spent the last 30 days brewing your Budweiser," claims the commerical. And, lest we become a vehicle for all things anti-In-Bev on this site, it does seem a statement worth unwrapping.
Lagers take longer than ales, that much any home brewer can tell you. And if you do a lager at home, you might be lucky to finish it in thirty days. There's fermentation times, and then there's the lagering process -- extended secondary aging at cold temperatures. Add in time spent planning the recipe, meticulously sorting through grains by hand, working the books, filming ads, and shmoozing with the brewery tours -- or whatever Budweiser's brewers are required to do beyond actually brewing the beers -- there's no way we'll build a case here that proves the advertisement false. We don't know.
That said, it probably doesn't take Budweiser thirty days to brew their beers.
Brew Your Own has a great step-by-step writeup of the process of making a lager, complete with information about how the big brewers cut time out of each requirement. So let's follow the lead set by the article, and do some simple math. With one thing in mind: Anheuser Busch InBev is the largest brewer in the world. They are probably most concerned with one thing: making the most beer cheapest. And cheapest most often equals quickest, considering the man hours and capital costs involved.
The Mash and The Wort
Really, this part of the process should be measured in hours, not days -- at most. But American Adjunct Lager mashes do have rice in them for the most part, and that requires a seperate cereal mash to keep things from gelatinizing. Fine. Yeast is important, and making a good starter kit can take two-to-three days... for a home brewer. Not for Budweiser. They've got yeast ready, constantly, no?
Let's assume the brewer has to do the cleaning, the prep work, and has to lead this mashing process -- where the reality is, he probably just comes in to make sure certain parts of the mash are going fine, in an automated line. Let's assume that he actually needs 1/4 of a day to prep the line and get the mash going. Are we really going to add in much more for the boiling of the wort? Okay, let's call it half a day. And we're being generous, because these are machines, not two drunk dudes in the back yard with the propane tank.
Fermenting
Now this is the part where you normally have no say in the matter. The yeast needs to eat the suger and poop the alcohol. Nothing you can do about it, supposedly. So, according to what we know in the public, here's your guide:
Recall the rule of thumb about the lager time frame being double of that for ales. If your ales typically finish fermenting in 7–10 days, 2–3 weeks is a good estimate for a lager. But, as with all fermentations, let the hydrometer or refractometer be the deciding factor rather than the calendar. In general, consider fermentation nearly finished when the reading is within a point or two of the target final specific gravity.
That last is a heck of a thing to consider. A big company like In Bev might have ways to pull the plug on fermenting the second the reading is within a point or two of final gravity aim. Maybe even earlier if you believe the lawsuits. But let's just take the bottom end of this range and assume they're edging up on it. 14 days.
Lagering
You need about a day to make sure the diacetyl is out of the beer, and then there's the lagering. From the piece:
How long to lager is a matter of some discussion. Light American lagers are typically held near freezing for 10–20 days, while some strong German doppelbocks are lagered as long as six months. For medium to high-gravity beers, Greg Noonan — brewpub owner and author of “New Brewing Lager Beer” (1996, Brewers Publications) — recommends 7–12 days per each 2 °Plato of original gravity. (One degree Plato is roughly equal to 4 specific gravity “points.”). For lower gravity lagers the time is reduced to 3–7 days. According to those guidelines, a 1.064 O.G. German bock should be lagered for 112–192 days, while a 1.040 American lager would be lagered 15–35 days.
Ah but yes, Budweiser probably doesn't care too much what Greg Noonan thinks. Let's take the 10 day estimate on the consideration that they are trying to get the product out the door.
Add it up, and you get 25.5 days! Hah! Oh Budweiser, lying about those extra 4.5 days.
But really there are a few take-aways. One is that 30 days is, itself, a fairly quick time for a Lager. If you took the slow approach to a lager, or even just paid attention to the leading experts in lagering, you'd be expected to spend 38-58 days on your lager, depending on how heavy it ended up. So, even if we take their word for it, and it's 30 days, they've cut the traditional time in half. (Even if the brewer isn't going to spend 25 of those days staring at the beer while it ferments and lagers, so that is already a marketing trick.)
And is it really fair to assume they haven't cut it further? There are experts that don't think much of the lagering process, like Dr. Charlie Bamforth at UC Davis. The whole thing is worth your read, but look at him lay into the 'lagering' or 'prolonged storage' part of the process:
Provided the brewer has delivered the desirable flavour and has encouraged the yeast in fermenter to eliminate the generally agreed no-no's (notably vicinal diketones, acetaldehyde and hydrogen sulphide) then there seems little point in leaving the beer hanging around. There is unarguable evidence now that this severely jeopardises foam. Having said which, there are those who maintain that prolonged storage is important not only for the slow purging of undesirable volatiles and adsorption on yeast of unwanted non-volatiles but also for the release of amino acids, peptides, nucleotides and organic and inorganic phosphates, accompanied by an increase in pH. They say it causes an increase in palate fullness and mouthfeel. The evidence is sparse. Why keep prolonged storage, then? For marketing purposes of course.
Well, wouldn't you know it. Just about the perfect place to end this rumination on the marketing of your Budweiser lager beer: In the end, it's always about taste.