To those thinking of culturing lacto from grains, I have successfully done it. I outlined it here
Basically, I created 500ml of a 1.030ish wort, and added in 1/2 c. of grains. I let it sit for a few days. By the smell of it I think it developed a little enterobacteria (or maybe lactobacillus just makes that smell), but then it started to ferment with an ‘unknown’ yeast – Either wild from the grains, or cultured from the ‘terroir’ of my kitchen (brewers, bakers, …?).
Nevertheless, I got good results from pitching about 250ml of starter into 2.5 gallons of wort and letting it sour before adding S-05 after 48 hours (it may have been 24… I should take better notes).
My recipe was around 1.035 and involved about 60-40 Pale 2-Row/Malted Wheat. I doughed in at about 1.5 qts/lb. for a protein rest at 125-130F for 20 minutes. I pulled a decoction to raise it to 148F rest for 60 minutes, then pulled a second decoction to raise the mash to mashout at 168F for 20 minutes. I threw in .75oz Hallertau with the second decoction and boiled for 10 minutes. Then I did a "sparge" à la the stove-top brewing, and brought to a boil to sanitize the immersion chiller.
Nevertheless, it sat in the carboy for 4 months before I got a sample. Clear, and refreshingly tart! I haven’t bottled it yet.
As for culturing lacto you have a few more options:
1. Buy a bottle of ‘Acidophilus’ from your drug store. It’s just L. acidophilus and will sour your beer without any trouble.
2. Make a starter from the ‘whey’ which forms on top of yogurt (like Stoneyfield, or Brown Cow). Stoneyfield has a number of lacto cultures such as L. bulgaricus, L. acidophilus, L. casei, and L. rhamnosus. If you make a starter, you can probably minimize the effect of the other things in the ‘whey’
3. Buy a yogurt ‘culture’ from a cheese making store. The commercial yogurt culture has L. delbrueckii which is common in brewing. However, it does have ‘milk’ and lactose’ in the culture…
As for bulk aging…I don’t think it’s necessary, but it may be fun if you culture a starter from grains. You might get something more than straight-up lacto and it could develop a pellicle and change flavors over time. I split my batch between pure culture (with the wild yeast) and culture and S-05. The pure culture batch has a pellicle and I haven’t tried it. I hope to the next time I brew (Thursday?). If it’s really good, I’ll bottle it by itself, if just pretty good, I might try blending it. If it’s terrible, I may toss it, or…bottle it for kicks.
Hopefully that helps. I don’t have a whole lot of experience. Given more time, I might try the Acidophilus method, and the yogurt method.
I do plan on racking a bigger (1.060) beer onto the yeast cake of my current BW….just to give it a shot. If they pure culture is very good, I’ll do the same for that… I’m just trying to decide if I want to do a light beer (still 60/40 barley/wheat) or one with some melanoidins.