Starters, pH, LAB, & Acids
Quite often we read replies on TFL that instruct the baker to mix his or her starter at high feed ratios in order to to lower the amounts of acid (and LAB?) in a starter. Doc and I were discussing the buffering effects of flour and pH. The following thought occurred to me.
Consider that a starter is over acidic and we want to remedy this.
- We refresh the starter at 1:5:5. Below are recent pH measurements. NOTE - in this case the starter is not overly acidic, but the information is used as a reference.
3.92 after 4 hr@ 82 F (starter at max rise)
5.47 mixed 1:5:5 starter (starter refreshed)
4.23 after 4hr 1:5:5 1x rise (4hr after refresh)
3.77 after 8hr 1:5:5 3.25 rise (starter has matured)
- So the seed that fed the refreshed starter was pH 3.92 and after refresh measured 5.47. - Let’s look at the same seed starter that fed the 1:55 and feed a companion starter 1:1:1, using the same culture as seed.
3.92 after 4 hr@ 82 F (starter at max rise)
4.66 mixed 1:1:1 starter (starter refreshed)
3.88 after 4 hr 1:1:1 3.5x rise (starter has matured)
We know and can see from the data above that the amount of flour used for each refresh has a particular buffering affect on the pH of each starter.
Since the high feed ratio increases the buffering affect of the starter, we can expect the LAB to multiply and produce acids over a longer period of time. Yeast are not affected by low pH but LAB are. A 1:1:1 refresh will buffer the pH less, thus shutting down the reproduction of LAB earlier than the 1:5:5 starter.
My Question -
Does a high ratio of feed to seed reduce the LAB and acids in a starter that is overly acidic?
Below are some of the data that I’ve recently measured in case anyone is interested.
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 remixu
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
3.78 1:1:1 out of fridge
4.69 1:1:1 refreshed with bran water
4.51 1:1:1 refreshed with spring water
6.51 bran water NOTE - I would expected the pH to be higher than the spring water. It was much colder (42F) than the
- - - spring water (~76F). Might that account for the bran water measurement?
6.67 spring water
Note - 1:5:5 refreshed 2 wks ago @ 5.69 - 2 wks in fridge w/hooch 3.74
