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Another Ph Question

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BrianOD's picture
BrianOD

Another Ph Question

I've got a WW starter going from refrig storage. It's been about 2 weeks since pulling them out of the fridge and I've baked two batches of rolls with the resultant starter. They were somewhat successful, dense, but with some oven rise. I'm looking for more rise out of the bread. I'm modifying the hydration in the recipe slightly each time to get a lighter crumb while maintaining some structure. I've been experimenting with different hydration levels and have been helped by a number of responders here on the website.

Today's question is in regards to the Ph of the water I'm using and whether or not it is inhibiting yeast development. I've been using store-bought spring water with a Ph of about 6.75. After reading about the pineapple method of starter creation and the reasoning behind it I'm wondering if feeding my babies with this water is slowing down the yeast growth. My tap water (from a well, no chlorine etc.) measures about 5.75 Ph.  My thinking is that if I use the well water in the feeding the overall Ph would not rise as much initially and the process of acidification would be quicker, bringing the starter quicker to that acidic comfort zone wild yeast apparently likes.

An FYI - the starter doubles in volume in 5 hours (like clockwork). There are no bubbles on the surface, no "bubbling up", but the body of the starter has many bubbles, both big and small. The hydration I'm using is about 85%. The temp of the oven is 75F.

Any insights/suggestions? Thanks

Ford's picture
Ford

Yes, it is lower case "p" and upper case "H".  There is probably little buffering agent in either the bottled water or your well water.  Given that neither is chlorinated, I would go with the well water;  its cheaper and you know the source of it.

To speed up the rise of your dough, and judging from your note it seems that you are not refreshing the starter before using it.  I keep my starters in the refrigerator.  When I want to make bread the morning before, I remove the starter from the refrigerator and refresh it in the ratioi of 1:1:1 (starter:flour:water)  by weight.  That evening I repeat the addition of flour and water in the same ratio.   The next morning my starter is ready to go.  Yu have to adjust the starting weight of starter so you do not make too much refreshed starter and remember to save some of the refreshed starter to put back into the refrigerator.  Some bakers prefer to use the ratio of 1:2:2,  do whichever works best for you.  The point is that the starter must be active when you use it.

Note that whole wheat dough is more sluggish in the rise than white dough, and more water is required to hydrate the bran.  You are using 85% hydration and that should not be the problem.

Ford

BrianOD's picture
BrianOD

pH, got it. Thanks for the correction.

I have been feeding the starter for about 2 weeks. It's now on an approx 7 hr feeding schedule, it grows to about double in 6 hours then recedes a little bit. At that point I'm taking 50g of the starter, 100g of ww flour and 115g of water, mixing the water and starter then adding the 100g flour. Into the oven at 75deg. I've got a rig with a light, dimmer and thermometer that keeps the oven at a pretty steady temp. I've got a sealed gallon plastic bottle of water in there also, just  as a temp stabilizing mass.

I made a second batch of the starter this morning, one with the store-bought spring water and another with the tap water. At 4+ hours there does not seem to be any difference between the two and both are right on the schedule to peak in 6 hours. So, apparently at this point in the process, the acidic water makes no difference to the starter.

What I'm looking for is a confirmation/denial that the starter has reached it's peak activity. There doesn't seem to be any surface bubbles in the jar at the end of the 6 hours. Is this the only sign that it is active or do some starters just not have this bubbling on the surface? The starter has bubbles throughout the material, just not at the surface. Is there something that I can do to push the starter over that assumed line of increased activity? Or do I just need to wait, feeding regularly and it will, at some point, decide to become more active?

BTW, when I measure the pH of the starter at the end of the six hours it is below my ability to measure, so something is changing the acidic levels.

 

Ford's picture
Ford

Don't worry about seeing the bubbles.  If the starter has doubled in volume it is ready to go.  As for the dough, it should really more than double before putting it into the oven.  Check it by pushing it down with two fingers.  If it immediately springs back, it has not risen enough,  if it never comes back then it may be over proofed.  Check out the finger poke test in the "Search" box on the top left side of the screen.

By the way, 75°F is a little cool for rapid proofing, 80°F is about optimum,  90°F is too high, and 97°F is deadly for the yeast.

Ford

BrianOD's picture
BrianOD

Ford, I'm confused about what you wrote about the temp for "rapid proofing". I thought the discussion subject was the starter stage of the bread baking process, not the dough proofing stage. Do both stages require 80 deg?

I'll try the poke test tomorrow when I bake some rolls.

 

Ford's picture
Ford

Whether we are talking about the starter or the dough in the speed of rising, we are talking about the little organisms that do all the work, ie, the lactobacteria  (Lb sf) and the yeast (c. milleri).  The answer to your question is therefore, yes, it is the same.  The table below gives the activity of these critters as in San Francisco sourdough.  I am assuming that the organisms in other sourdoughs behave much the same.   My reference for this is found in: Gänzle, Michael et al., Modeling of growth of Lactobacillus sanfranciscensis and Candida milleri in response to process parameters of the sourdough fermentation, Applied and Environmental Microbiology, July 1998.  Also in Sourdough Bread Science, eGullet Society for Culinary Arts & Letters; http://www.egullet.com/imgs/egci/sourdough/science.html.

San Francisco Sourdough Activity

Temp   Temp    Lb.sf     Yeast

°C          °F                    (C.milleri)

 2          36       0.019     0.004

 4          39      0.026     0.008

 6          43      0.035     0.013

 8          46      0.047     0.021

10          50     0.063    0.033

12         54      0.084   0.052

14         57       0.11     0.078

16         61       0.14     0.11

18        64       0.19     0.16

20       68       0.24    0.23

22       72       0.30     0.30

24       75        0.37     0.37

26       79       0.45     0.42

28       82      0.49     0.42

30       86      0.61      0.35

32       90      0.66     0.20

34       93      0.66     0.05

36       97      0.58     0.00

38     100     0.39

40     104      0.1

41      106     0.00

I hope this helps,

Ford

BrianOD's picture
BrianOD

Ford, thanks for the chart. I've got some rolls proofing (after taking the dough out of the fridge) this morning. I'll do it at 85deg for a while (until the "poke" test says they're done).

The starters have been whiling away the hours at 75 deg. I'll take one of them and put it in the 85deg environment of the proofing dough and see what happens.

I remember reading somewhere that the cooler range of temp promotes the sour flavor. Is this accurate? Would proofing the rolls at 75deg for a longer time promote the sour animals while the yeast is doing it's thing?

Ford's picture
Ford

There is a discussion on this at: http://www.thefreshloaf.com/node/23608/bread-not-sour-enough.

Essentially it says to proof at a higher temperature and to use longer times at bulk proofing stage.  You can see other discussions by using the search box.

Ford

henkverhaar's picture
henkverhaar

Tap water will generally have a ph of around 5.5 - that is from the carbonic acid that finds its way into the water from the CO2 in the air. Any water that is in contact with air will eventually (and eventually comes about quite rapidly) end up at this pH. Even your pH 6 (so it has to be still water), degassed water. Nothing strange there. Unless there is a significant amount of buffering salts in your water - which would be more likely for bottled water than for (most) tap water.

Don't worry too much about water. Unless it is chlorinated of course.

BrianOD's picture
BrianOD

The pH non-issue bears out after observing the difference in starters with and without the tap water, so I'll save myself the trouble of buying the spring water from here on in. Thanks