Wed Feb 23, 2011 2:32 am
Ignore the wisdom of Brewinhard and the BBB at your peril. (Both have been very helpful with my own experimentation with lacto and other "wild things".)
If you truly only want lacto and not a mixed culture, then you really need to buy a lacto starter (You can also look at yoghurt starter cultures from health shops as a source of lacto; they normally come with quite a good quantity of lacto although they normally have a couple other bacteria in there, too.).
You should also note that pediococcus will continue reproducing and fermenting down to a lower PH than lacto so a pedio/lacto blend would be the best thing for getting a lower PH (although pedio is quite SLOW to do its work vs. lacto). (Lacto will stop reproduction at ph 3.8 while pedio will continue down to 3.4; both will continue fermentation a bit below these numbers.)
As Brewinhard mentioned, you don't want to hop you growth medium for lacto (unless you keep something like some old whole leaf Saaz in a drawer at room temperature exposed to air for a long period of time (I keep a bag of Saaz ina drawer for just this type of situation); above 10 IBUs can start impacting lacto growth and fermentation.
You also want to be careful to minimize oxidation of the lacto growth medium. (I know, it's a counter-intuitive thing to do after brewing with just yeast for so long.)
Beyond that you can ferment at near human body temperature, 98.6F (although Wyeast says a max of 95F) to favor the growth of lacto (you can do this with mixed dregs, too which will FAVOR the growth of lacto although the other bugs will still be there.). -I did this recently using a Wyeast lambic blend and I have almost EXCLUSIVELY lacto-derived flavors at around day 100 right now; VERY, VERY little brett flavors and the brett strain in the lambic blend is NOT subdued; it's a super barnyard funk strain for what that's worth.
As you already know; keep oxygen away also to prevent acetobator from setting up shop (and impacting lacto and or pedio growth/health); if you ferment in a corney keg you can keep a very low pressure CO2 blanket on it and keep O2 away VERY effectively.
Lacto also only ferments Glucose/Dextrose (same thing) so decreasing the percentage of malt/malt extract and increasing the percentage of corn sugar in your starter wort should make the lacto happier.
A little starch has been shown to have a positive effect so throw a little normal (non self-rising) flour in with your starter wort. As the data sheet below shows, for some reason (this is also counter-intuitive) 5% honey has shown in recent years to help lacto growth, too.
Here's the raw data on the organism that might be of assistance:
Lactobacillus:
· Ideal Temperature: 98F/ 37C (60-140F, 16-60C) –Wyeast says Max 95F
· Ideal PH: Above 3.8 (reproduction stops at 3.8 -although fermentation can continue below this
· O2 Preference: facultative anaerobe or microaerophilic (depending upon who you ask), prefers very little O2 but can ferment in its presence, too
· Hop Resilient: No (L Delbruckii), greater than 10 IBUs can impact it, other strains are more hop resistant (L Brevis)
· Alcohol Tolerance: 8% ABV (works much slower when ABV rises)
· Sugars Consumed: Glucose/Dextrose (Same Sugar) -L Delbruckii-specific info
· Acids Produced: Lactic only -L Delbruckii-specific info
· Time: 4 days for optimal growth under traditional techniques
· Starch: Positive effect
· Shape: Rods to Coccobacilli (short rods to elongated spheres)
· Nutrient Requirements: Carbs, amino acids, nucleic acids, vitamins, fatty acids
· 5% honey in starter can help growth rate and rate of production of acid
· Presence of acetic acid has a slight negative impact on health
I'm not recommending anything I haven't tried; I used the above tips in growing up my own lacto starter and got quite a growth of lacto very quickly; the PH dropped very quickly, but I don't think it dropped super far. (My PH papers bottomed out before they became useful.)
Adam
