Starter Feeding Ratio

My first reaction was the fridge at 9C. Is that an ordinary fridge with milk, meat etc. too or one for specific uses? A fridge for every use should be 0-4C for food safety, and at those temperatures the yeast activity from sourdough seems to come to a complete halt. I don’t know about 9C though.

When most people talk about putting the starter in the fridge, it’s with 0-4C, so keep that in mind.

You never really have to worry about the LAB. If during a particular feeding cycle they are hindered for whatever reason, on the next feed they are likely to bounce back as their cell numbers are always higher than the yeast.

For example, if the starting pH is low, it means the LAB produce less acid before they shut down again. And so, on the next feed cycle, because less acid was produced previously the starting pH will be higher and therefore open the door again for LAB.

Building on what I believe to be the seed of the question, then ideally feeding at high ratios consistently would be a default approach. In so much as, you can always satisfy the optimum pH range for growth of LAB. However, in doing so the TTA would remain consistently low but relative to the buffering capacity of the flour used.

A higher or persistently elevated TTA is only ever achieved by letting the cycle run past the end point for growth (e.g. traditional SF sourdough process), again relative to what the flour can buffer.

Those are my thoughts at least...

This EXACT statement by Doc, “ If your post-refresh pH is too low, the pH of the resulting levain quickly gets down to 3.8 and the LAB stop replicating while the yeast continues to grow exponentially until the glucose is consumed or you use the levain and feed it some new starch.  When feeding a starter I like to be up around 3:13:16 if the weather is warm, with a little more seed when it is cooler but always at least 1:3:3 (for white flour).” also made a big impression on me. For at least the last year I mainly stayed with 1:1:1. The reasoning - my starter was very active and strong. There was (and is) a concern that higher feed ratios could introduce new strains of microbes and alter a good thing. BTW, very strong white flour was fed, reasoning that the gluten would break down less. 

At this time, my practice to to fully mature the starter. It is then stirred down with a bite more flour and directly refrigerated. The extra flour (IMO) benefits 2 ways. It provides additional feed for the mature starter during refrigeration and it also stiffens the starter a bit, making it somewhat stronger.

But for an unknown reason my starter started to wane a bit. So higher feed ratios coupled with ~20-30% whole rye was introduced. Starter picked up.

Micheal’s reply (“ You never really have to worry about the LAB.”), also seems to confirm what I have believed for many years. The production of LAB is super simple and their resulting acids are not difficult. I back that statement with this. Take ANY SD starter and allow it to over-ferment. Taste it if you dare. I don’t measure TTA, but you can be sure it is high.

With the above paragraph as a foundation, I believe that any SD starter (acidic or not highly acidic) can and will produce extremely sour tasting bread if fermented at either warm (lactic) or cool (acetic) temps and given enough time (important point) to build the desired acids. That bread will taste sour.

I may not have the science right, but the experience with hundreds of SFSD loaves have me convinced.

Great topic, Lance.

Thought -
Maybe starting with a lower pH starter (feeding 1:1:1) is a good thing when focusing on maximizing the yeast.

Here are my notes pertaining to Ph and my starter. It may be of interest to some.

pH Starter Stats

4-26-21

3.71 refrigerated starter for 7 days

4.48 after mixing 1:1:1

3.95 after 4 hr @ 82F. 3x rise (*)

4.73 after mixing 1:1:1

3.92 after 4 hr@ 82 F

- - 3.77 after leaving (*) on counter at ~72F for 4 more hours

4.66 mixed 1:1:1 starter

5.47 mixed 1:5:5 starter

3.88 after 4 hr 1:1:1 3.5x rise

4.23 after 4hr 1:5:5 1x rise

3.77 after 8hr 1:5:5 3.25 rise

4-27-21

3.62 starter left out on counter 24 hr

5-2-21

3.80 1:1:1 refrigerated since 4/26

4.57 1:1:1 remix

3.66 1:5:5 refrigerated since 4/26

5.31 1:5:5 remix 1:5:5

3.90 1:1:1 after 4 hr matured

4.13 1:5:5 after 4 hr

3.67 1:5:5 after 9 hr 

5.41 SFSD dough BF 4 hr @81F

3.91 SFSD after 2 folds 

3.89 SFSD after 1 fold

3.65 SFSD 1 fold end of 16 hr BF

3.73 SFSD 3 fold end of 16 hr BF

5-9-2021

3.56 1:5:5 out of fridge since 5/2

3.78  1:1:1 out of fridge since 5/2

4.69 1:1:1  refreshed with bran water

4.51  1:1:1 refreshed with spring water

6.51 bran water (bran water was cold ~44F, but meter used ATC)

6.67 spring water (spring water was at RT ~70F, but meter used ATC)

Note - 1:5:5 refreshed 2 wks ago @ 5.69 - 2 wks in fridge w/hooch 3.74

4.05 1:1:1 Bran Water matured in 3hr. This is unusual, normally takes 4hr @ 82F

3.92 1:1:1 Spring Water matured at 4hr, which is the norm

5-10-21 

3.81  1:1:1  out of fridge - since 5-9-21

4.69  1:1:1 after refresh 

3.96  1:1:1 at maturity

4.79   1:1:1 after refresh

4.07 1:1:1 at maturity dropped temp 4F

5.88   Water and flour only (autolyse)

5.98   Water and flour after 2.5 hr autolyse 

5-17-21

3.73   1:1:1 out of fridge

4:53  1:1:1. After refresh

3.94 1:1:1 after 4.5 hr

4.81.  1:1:1 after refresh

3.93.  1:1:1 after4hr

4.05.  1:1:1 after adding ~3g flour

5-24-21

3.79.  1:1:1 out of fridge 

4.55   1:1:1 refresh 30% rye

3.99.  1:1:1 at maturity 

4.68   1:1:1 after refresh all white flour

3.97.  1:1:1 at maturity 

5.09  10:16:20 refresh

3.95.  10:16:20 at maturity 

6/14/21

3.83 1:1:1 out of fridge

5.21 after 1:3:5 refresh

3.91 over matured 

5.17 1:3:5 refresh

4.11 1:3:5 25% whole rye at maturity