Prematuration - amount of culture guidelines?

[ArnaudForestier]

Hi all, this probably belongs in its own thread (I tagged it on the end of a post in an unrelated thread). 

Plan on prematuring some creamline milk with 4001, just don't have any amount guidelines.  Gianaclis mentions 12 hours at 45-50, Yoav mentions 24-36 hours at cooler temps, but I don't see anything anywhere on specific amounts.  Absent that, I was thinking 1/64 tsp (just got my gram scale, so will maybe weigh it instead) per gallon.  Anyone with any ideas?  Perhaps a certain percentage of the batch inoculation (e.g., if doing a b.e. 1%, use 0.1% in the prematuration).

Thanks, anyone and all.

Paul

[Geodyne]

I tend to go for 1/32 tsp or so per quart, but I bring my milk to the boil, cool it to 27-30C, then innoculate in a mason jar and wrap in a towel for 12 hours or overnight. I find that if I use less with that technique, the culture isn't set when I would like to use it the next morning. I think 1/64 tsp would take a very long time to culture.

I'd be very interested to see what method others use.

[Sailor Con Queso]

Paul,

Why do you want to "premature" instead of using a Mother Culture?

[ArnaudForestier]

Sailor, sorry, just realized you asked "why," not "what." 

This isn't in place of the primer culture, it's earlier than the day of the make; just a very small amount, in the cold milk - emulating farmhouse practice with raw milk, combining evening and next morning's milk.  Gianaclis mentions 12 hours at 45-50 F, and Yoav, in his reb thread, mentions 24-36 hours at 38F or so, cooler temps.  A way to treat the pasteurized milk, to give it some emulation of raw, combined milks - before going into the vat.

I'll be using a MC as well, in the vat, at about 1%.  Just recall Pav talked somewhere on this as well, can't find it. Playing with my food, basically.  As always.  

[scasnerkay]

I have this somewhat vague note from a class with Peter Dixon:
Pre-ripening:
Milk can be held at 50 degrees overnight, with Flora Danica for 10 to 12 hours, then can be pasteurized, or cooked in recipe. Can be done with a blend of raw and pasteurized milk as well, or already pasteurized. Make sure to measure pH before cooking! May need to decrease other starter.

[ArnaudForestier]

Thanks, Scasnerkay, reading that, I'm wondering if Gianaclis was gleaning from her notes, too - I know she studied and/or worked with Peter Dixon, from what I recall from her book. 

What I'm wondering about if there are quantity guidelines (and this would likely be dependent on specific cultures, too, I know - e.g., FD would be dosed at a different rate from MM100, from MA4001).  I may be overthinking this, but wondering if my parsing 1/64 tsp per gallon is far too much, basically.  I don't use DVI for vat inoculations, anymore - I use Sailor's mother/primer culture method, and that's an extremely reliable means, in my experience - so was hoping to experiment with this pre-maturation in view of later priming.  Do you happen to have any quantity notes, there?

Many thanks for the post!

Paul

[linuxboy]

Prematuration the way you describe it is done at .2-.3% bulk equivalent w/v. And yes, held at 50 provided milk is good. Keep in mind that staph aureus produces toxin above 45F.

[ArnaudForestier]

Perfect, thanks, Pav. 

Do you see any utility at lower temps, to stave off psychrotrophic bacteria?  I'd imagine this particular method applies more to raw than pasteurized milk (i.e., a safeguard in raw milk, as opposed to a "character builder" in pasteurized milk), but curious on your thoughts for this purpose.

[linuxboy]

to stave off psychrotrophic bacteria?

I don't know why exactly, but this does work (I will find out why eventually, this topic has little published research). Milk ADV is also lower with a slight inoculation in the bulk tank.

(i.e., a safeguard in raw milk, as opposed to a "character builder" in pasteurized milk

Can use both. Temp control helps to determine function. ie, pasteurized milk preripened at 50F is great for flavor. Keep in mind that meso bacteria will work at temps that low and their metabolite products will differ at the lower temps. Those organic acids serve as flavor precursors. It's kind of like lagering vs making ale. Very little research on this topic, too, on metabolite and flavor production at different temps. Not many people in the business care, because rapid acidity is desirable for manufacturing.

[ArnaudForestier]

Thanks very much Pav.  On the different temps and different metabolites, I did wonder about that because I know it's not a linear relationship, certainly, all the metabolites that can spring from ripening, at different temps.  I just don't know a thing about what tendencies will come from what temperature ranges.

I am very interested in this, I think it was actually you who piqued my interest, and perhaps that of others, discussing this somewhere.  I'm using pasteurized milk for now, so would like to try this.  One thing I have to ask, is the whole DVI/DCU/U thing - I don't tend to keep packets but rather transfer them to ex-med containers, airtight (I should start reading the packets and logging them).  So, basically, I am considering just using a b.e. portion of primer culture, then continuing on with the vat inoculation the next day.  Is this reasonable, to use a liquid mother culture for prematuration (again, the purist in me begs the question, is there something "adulterating" in flavor about using cooked milk in a 12-hour prematuration v. DVI as a pure prematuration inoculation...probably not....?)?

[linuxboy]

I just don't know a thing about what tendencies will come from what temperature ranges.

This is one of the remaining gaps in my knowledge. I know the LAB metabolic pathways change with the temps, and it is strain dependent. There's the classic lactic acid isomer production but LAB also produce products such as acetyladehyde, ferulic acid, hydrogen peroxide and other oxygen metabolites, and various bioactive peptides. I haven't had time to dig into this and figure it out more.

reasonable, to use a liquid mother culture for prematuration

That's best, actually. Rehydrating DVI in cold temps leads to lower viability numbers. It works well. Also easier to dose.

[ArnaudForestier]

Great, thanks, Pav.  Yeah, on dosing the DVI, I was really scratching my head.  So, per gallon of milk, I'm getting anywhere from .8 ml to 1.1 ml of mother culture - hope that's right.  I now have three fridges, humidity controlled by John @ PC's really remarkable system (I truly love mine so far - effortless, controls really well, like his thermostatic controller), one a dedicated tomme and the other to be dedicated reb, so onwards. 

Cheers, friend. 

Paul

[linuxboy]

You can use a bit more starter for preripening if you want. Overnight, the drop should be .1 -.15 (which is part of why we suggest to wait for the delta before adding rennet). If it's lower, you can use a bit more culture. Bulk tank amounts for 3-4 day preripening are different. Can use even more then, assuming milk will be pasteurized.

[ArnaudForestier]

You can use a bit more starter for preripening if you want.

Would 1.5 ml be reasonable, 0.04%?

Overnight, the drop should be .1 -.15 (which is part of why we suggest to wait for the delta before adding rennet). If it's lower, you can use a bit more culture.

You mean, test the next morning, and if it's not as much delta, use more culture in the vat than I had planned, or just log this for next time, and use more in the prematuration inoculation?

Bulk tank amounts for 3-4 day preripening are different. Can use even more then, assuming milk will be pasteurized.

Cool, thanks, Pav.

[linuxboy]

Would 1.5 ml be reasonable, 0.04%?

If overnight? I made a typo in previous post, it's 10x that. start with .2%

just log this for next time, and use more in the prematuration

This.