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Reducing acid load in starter (warmer weather)

DanAyo's picture
DanAyo

Reducing acid load in starter (warmer weather)

Now that the temperatures are getting warmer, I noticed my starter is becoming more acidic. The starter has been maintained in a proofer @ 76F, but the ambient temps are getting warmer than that. For the entire winter months I fed twice a day; 1:3:5 with AP flour.

My goal is to maintain a starter that maximizes yeast.

I dropped the hydration a little and also increased the flour a slight bite. I would prefer not to refrigerate and do not want to feed 3 times a day.

How long should it take to restore the starter’s balance back to favor the yeast?

Looking for ideas and a better understanding.

Dan

Doc.Dough's picture
Doc.Dough

How are you determining the total acid?  TTA is the accepted assay and it is a difficult measurement to make.

When you say you are feeding twice each day, do you mean that you are feeding at 12 hr intervals?  If it is kept in a 76°F proofer, what temperature is it now that the weather is warming up. Certainly above 76°F unless you keep the proofer in an artificially cool location.

Your starter will have a life of its own and might benefit from a single feeding per 24 hrs to assure a more stable cycle, but you can control the acidity of the bread by controlling the levain build.  Tell us what you do to make your levain and the formula and process for making your bread.

DanAyo's picture
DanAyo

Doc, the starter smells and taste more acid than usual. Since I’ve been feeding 2x for over 6 months, I am very familiar with the starter.

I feed every 12 hr.

I’d love to be able to feed every 24 hr, but I’m not sure this is possible without reducing the temperature. In the summer it gets very warm. I estimate a peak of 80F. At times, possibly peaking a little higher.

I prepare my Levain using 1:5:5 about 6 - 8 hours in advance of mixing. I like a very sour flavor, but I get it in the extended fermentation of the mixed dough. BF as a long as 16 - 17 hr @ 77F (DT). But since it is getting warmer, I will need to reduce the BF time. The levain is 2% flour of the total flour prefermented. So for 1 kilo of flour the Levain consist of 40g @ 100%.

Dan

 

Doc.Dough's picture
Doc.Dough

Lactic acid is what you taste in both starter and the final bread, but acetic acid is what you smell as the sour in sourdough.  This is largely due to the differences in molecular weight and the resulting differences in vapor pressure. Acetic acid has a high vapor pressure and lactic acid has a very low vapor pressure.

The strength of the acid taste in sourdough is controlled by how much acid is in the mix and not by the pH of the dough (this is a hard thing to understand but is a result of both lactic and acetic acids being "weak acids" so that they are not fully ionized).

That said, you probably are getting more acid (TTA) in your starter whether from warmer weather or from something else, but that does not mean that you have to have a higher TTA in the bread.  Total acid production is spread over the levain build, bulk fermentation and final proof of the dough.  It depends on two things - the population of LAB and the availability of nutrients.  Since the LAB replicate faster than the yeast do, they get out in front and replicate and produce acid until the pH of the environment gets down to around 3.8 at which point the LAB slow and then stop replicating.  From there on out you have an approximately fixed number of LAB producing acid at a rate that is mildly dependent on pH and more strongly dependent on available nutrients.  On the other hand, yeast is pretty insensitive to pH and just replicates until the usable nutrients are depleted.

You have a couple of options if you want a yeast-enhanced dough (relative to LAB).  The first is to arrange for your starter to have a low ratio of LAB:yeast.  You can do this with cultural practices or by selection of starters that exhibit that characteristic.  Second, you can arrange for your levain to have a low ratio of LAB:yeast.  You can do this by adding a sufficient amount of an acid to the dough (or even better, to the levain) to reduce the pH to 3.8 or below and slow/stop the replication of LAB so that you have only the acid that comes from the prior stage and none (very little) that comes from bulk ferment/proof.  You can also use a relatively large fraction of pre-fermented flour (40-50%) and use the levain before it is fully developed (i.e., somewhere around the point when the yeast is generating CO2 at the peak rate rather then waiting for the yeast population to peak). This shortens the amount of time that the LAB have to make acid (remembering that the LAB population has already stopped growing).

Acids that you might try include citric and malic.

DanAyo's picture
DanAyo

Doc, you mentioned TTA on a number of replies to me. I am a curious sort. Which test kit do you use for the TTA?

Do you think it is a good idea to run this test?

Also you mentioned adding acid to the starter. I am aware I of the “pineapple solution”, but never considered acid for a viable starter. Is there a danger of harming the or destroying the LAB by using acid In an active starter?

You wrote, “You can do this by adding an acid to the dough (or even better, to the levain) which will reduce the pH to 3.8 or below and slow/stop the replication of LAB so that you have only the acid that comes from the levain and none (very little) that comes from bulk ferment/proof.”  -    My goal for keeping my starter “sweet” is because I want it to be as powerful as possible in order to increase the highest bread. I am happy with the “sour” I get by using the BF and proof to raise the LAB.

I appreciate your help. I don’t always understand all of it, but I read and reread your replies in hopes of grasping all or most of it.

Dan

pul's picture
pul

By feeding twice a day, do you have to discard a lot? How do you manage it?

DanAyo's picture
DanAyo

Paul, I feed 1:3:5. In order to reduce waste the actual mix is 3:9:15. So from 27g I only keep 3.

I am in the process of feeding 2.5:9:15 at the present time.

Maybe I need to give it more time. The starter does not smell extremely strong. I want a “sweet” starter so that the yeast is maximized.

How long would you expect it to take with a feeding like this to freshen up? Are we talking days or weeks?

Dan

UPDATE; I checked it today and it seems to be slowly returning to a less acidic state, as gauged by smell and taste.

Edo Bread's picture
Edo Bread

Why do you not want to refrigerate?

DanAyo's picture
DanAyo

I bake quite a bit. It is my belief that a starter is more active if maintained without refrigeration. I’d prefer not to put it in hibernation.

Dan

Edo Bread's picture
Edo Bread

I would not call it going into hibernation, but slows it down. Depending on how warm it is when you put it in, you can reduce the number of feedings but keep it very active. Personally, it seems to me people waste a lot of flour and energy with so many feedings. I do a fraction and have very active starters, oven spring and can very the sourness easily.

Doc.Dough's picture
Doc.Dough

I have lots of data on three different starters growing under refrigerated conditions. For cultures that are refrigerated when they have lost about 2% of the weight of the added flour from the current refresh cycle, they will continue to produce CO2 for about a month if kept at 38°F though if you let it go that long you will need to run two or three refresh cycles at room temperature to get the LAB:yeast ratio back to where you want it (100:1).  However, if you refrigerate it for only 7 days, there is no detectable change and in one refresh cycle you are back up to normal performance.  Thus for a starter that is refreshed as 3:13:15 (that is 3g of starter: 13g water: 15g flour) for a total of 31g, allowed to ferment at ~70°F until it has lost 300mg of weight (2% of the 15g of flour) and then refrigerated for a week, you can take it out, use 3g to seed a refresh cycle and use the remaining 26g (after losses to the container and the spoon) to initiate a levain that is mixed as 26:260:260 to make 535g of usable levain (again after losses to the container and the spoon), which is plenty to start a few Kg of bread.  To do this you need a pretty good scale (I use a 120g capacity scale with 1mg resolution which gives more than adequate resolution to detect when the starter has lost 300mg and is ready to refrigerate).  It turns out that the "2% of added flour" point is pretty close to when a 3:13:15 refresh wants to collapse on its own.

Full blog post on the 2% weight loss rule is here!

bikeprof's picture
bikeprof

the same principles apply here as always...if it is getting too ripe in the time frame you have to work with...lowering either the temp or the inoculation percentage will have the greatest effect, and since you are limited on temp controls, and have already reduced hydration a bit...lowering the feeding ratio seems to be the best tool you have.

Even if you feel like you are already at a low feeding ratio (not sure that is true), your starter and conditions might warrant going even lower (my levain has ripened just fine in 12hrs at 67F with only 1.8% of its flour in a mature starter, at 100% hydration and with 25% whole grain flour in the mix - just as one example of not following common standards).

Also, since this is not a process of trying to select for different strains of bugs over a process of generations, the main effect should be right away (noting that some additional acid will carry over for the first refreshment, then a very very small amount decreasing after that).

DanAyo's picture
DanAyo

BikeProf, you said, “(my levain has ripened just fine in 12hrs at 67F with only 1.8% of its flour in a mature starter, at 100% hydration and with 25% whole grain flour in the mix

If I understand you correctly, I am blown away :D

Do I understand this correctly? 1.8g starter, 100g water, and 75g flour/ 25g Whole Wheat. And it matures in 12hr @ 67F? Did I miss something? I often mis-read things.

At 66 yo I am consistently learning. The Internet is a gift to those that inquire...

Dan

bikeprof's picture
bikeprof

You are correct (even though I didn't word my description above very accurately).

But that is for the LEVAIN (I keep my mother starter a bit riper, and at a higher inoculation, but still low by most standards...it is very active and well adjusted to lower temps).

NOT a recommendation, just another illustration 

 

dabrownman's picture
dabrownman

LAB to yeast ratio in a a starter, levain and dough.  The NMNF starters 2rd stage stiffens it up and lets it rise 25% before refrigeration taking into account Doc's 2% drop in rate before refrigeration.  after 12 weeks stored at 38 F I can take 5 g of NMNF starter out of the fridge, add 50 g of flour and water each to it and it will double and be ready to raise a loaf of bread in 12 hours on the counter at 76 F,  At 80 F it will double in 10 hours and at 84 F it will double in 8 hours.

at 24 weeks of storage at 38 F the same mix if 5 g of starter 50 g each of flour and water will double in 12 hours on the counter at 84 F.

The acid load in 5 or even 10 g of starter is minuscule no matter how much acid is present and it is never an issue when making bread of any kind if you aren't using 250 g of starter in a 500 g loaf of bread.  The important things are temperature, hydration, refresh rate and amount of flour, kind of flour and LAB to yeast ratio in the starter, levain and dough.

Doc.Dough's picture
Doc.Dough

While I generally see a roll off in CO2 production rate after a month, I have not extended the refrigerated test much beyond that.  But I have recovered starter samples that were long forgotten in the back of the top shelf of the refrigerator and they come back to life just fine thank you and make good bread.  Probably not the same LAB species as it started with, but good bread all the same.

howyadoughn's picture
howyadoughn

How Ya Dough'n everyone. I live in South Florida and I'm concerned my SD starter is becoming a little to acidic. How do I test this. Also how would humidity affect my dough? I try and keep my restaurant at 72 degrees but with my pizza oven its hard to keep it that cool.  PLEASE HELP ME 

Doc.Dough's picture
Doc.Dough

Humidity has NO effect on your dough.  If you are making pizza, the dough should be aging for ~24 hrs before use.  That requires a refrigerator.  Put your starter in the refrigerator and adapt the refreshment process to the performance of the refrigerated starter. High acidity is not an issue if you refresh often enough (i.e., before the starter has lost 6% of the weight of the added flour), but prefereably when it has lost 2-4% of the weight of the added flour.

Full story on the 2% weight loss method here.

 

howyadoughn's picture
howyadoughn

thank you for the quick response. How would I measure that?

Doc.Dough's picture
Doc.Dough

What kind of a scale do you have? And please describe in detail your starter refresh cycle. 

howyadoughn's picture
howyadoughn

I have a regular digital scale that goes to the hundredth. My feeding schedule is a little funky because i'm trying to scale the volume of my starter up for commercial purpose. 

 

Having said that, I feed a 1:1:1

and I feed once a day with AP flour

DanAyo's picture
DanAyo

What temperature is your starter kept at? A 24hr at 1:1:1 is very unusual. 

I am interested to learn.

Danny

howyadoughn's picture
howyadoughn

 feed it in the morning and use it 3-4 hours later but its kept at room temp. Roughly 72-74 degrees. 

DanAyo's picture
DanAyo

Dough’N, please let me know if my understanding is correct.

  1. your starter is kept on the counter at 72-74F and never refrigerated
  2. it is fed 1:1:1 with AP flour
  3. it is fed only once per day, so every 24hr

If this is correct, I know why your stater is so acidic.

Please confirm or correct my understanding of your starter maintenance.

Danny

Doc.Dough's picture
Doc.Dough

Here is a link to a 2016 paper on how to refresh starter and why.  It is not done yet because I keep learning more, but it is complete enough that it should be useful for your purposes.

1:1:1 is a refresh ratio that will not work well unless you are pushing for yeast over LAB, and it is unsuitable for 24 hr refresh cycles at high temperatures.  A minimum of 1:2:2 to recover a 100:1 LAB:yeast ratio and perhaps 1:8:8 or 1:16:16 mixed with cold water might work better. It is fairly tolerant to over fermentation so weight losses up to 4% oof added flour don't put you at any great risk of underperformance though you should strive to be consistent from day to day so that your timing stays under control.

Even if you want to use it 4 hrs after mixing, you need to refresh a 1:2:2 or greater to maintian the LAB population and starter acidity, and I don't think that is going to work unless you increase the temperature to somewhere above 30°C/86°F.

For commercial use, where you may maintain 20 Kg of starter, you should be adding at least 8 Kg of flour when you refresh. So 2% of 8 Kg is 160g which is how much weight loss you should expect before the starter is ready to use.  And that is big enough for you to find it even if your scale resolution is 10g.