How to increase STRENGTH of starter

I am not certain of this, but from a lot of reading, I think if you want the sort of starter that will triple quickly, you need a lot of a commitment. I think it would involve keeping it out on the counter at a nice constant warm temperature and feeding two or three times a day.

But it depends whether you are really talking about speed or volume. My starter triples, but it does it slowly because of the cool temperatures in my home. I don't mind this, as it also stays at its peak for a long time, giving me a longer baking window. I can speed it up by controlling the temperature that it sits at.

I suspect that any well maintained starter, will be very healthy and active, but will just take longer or shorter to peak based on all the variables.

Something I seem to have observed with my own starters (I maintain 4, for no particular reason!), I keep them in the fridge, take them out and feed once a week, but the ones that have been baked with in the last week, even though it may be the same number of days between being fed as the ones I haven't baked with, get lively and active faster than those that are just being maintained. So I am assuming that building them to bake encourages that activity. So I now try to ensure I bake with them all regularly. I suppose that observation backs up what I first said, the ones fed more frequently are more active more quickly. But, a couple of feedings will get any of them nice and active.

One other personal observation, is that it has taken a long time for my starters to get to the point where they will triple rather than double, so as well as a good routine it maybe that how old the culture is has something to do with it.

yeast love 82 F the best and feeding it every time it doubles, even if 4 times a day will give you the most your starter has when it comes to raising a loaf.  This comes at a price 4 ways.  The cost of feeding, the cost of personal time, huge waste and a much less sour bread.  Developing a starter for yeast and rise is vastly different than developing one for Lab and sour.

It depends what you are after.  i prefer no maintenaince costs, no time in maintenance, no waste, stored in the fridge and very sour.

Happy baking 

refresh daily and keep temperatures around 22°C. Food is more concentrated, less diluited when the starter is stiff.

By stiff I mean as dry as you can handle, even down to 45% if necessary. Also, use stronger flours (bread-) rather than all-purpose flours.

I observed countless times that liquid starters suffer a lot when tenmperatures fall, while they really thrive and explode when temperatures reach at least 25-26°C, thus now as a rule I use stiff starters by winter and liquid starters from spring to mid-autumn.

In any case stiff starters never suffer, neither with cold nor with warm (or hot! as in my house by summer when I reach 35°C!!) temperatures.

The best time to strengthen a sourdough culture starter is when there is a variety of yeast growing in the culture and the starter has not settled in to one particular eating pattern, yeast are competing for dominance, the first one to two weeks of life in the starter, when the yeast have made themselves known.  

When the yeast have finally become active there are all kinds of yeast, all budding at various speeds when fresh flour is added.  Now is the time to settle the starter into a time frame to help them sort themselves out to the schedule you desire.   They depend on the bacteria to help them.  How you choose to feed the starter and at what temperature  has a great influence on which wee-beasties survive to reproduce.  

If you put the culture on a 24 hr feeding time with enough flour to peak in 24 hrs,  you are in fact encouraging those yeast that take up to 24 hrs to multiply.  If you now drop back to 18 hrs, those yeast in the starter that require 24 hrs are suddenly discarded and those that multiply sooner outnumber the 24 hr beasties.  The 24 hr slow beasties can no longer compete for food.  The gradual elimination process of feeding and shortening the peaking time (which happens naturally if temp and food stay the same) will boost the production of faster more agressive yeasts.  With each consecutive feed, those yeasts that can get to the food and reproduce quickly to live past the next discard and get fed.

First, in order to increase yeast numbers, there has to be wild yeast to start with in the starter culture.  If you can't smell yeast or beer, then wait a little longer for the developing culture to progress until it does.  No need to feed lots of flour until  the yeast are there to process it.  Overfeeding at this stage (is in my opinion) the number one problem in getting starters started.

At first this all sounds more complicated than it is but easy to catch onto.  Letting the yeasty smelling starter feed and reach peak volume is a good way to insure that the yeast are increasing and there is a healthy number of yeasts in the culture to survive the next discard and feeding.  At peak or when the starter starts to level out, reduce the amount of starter and feed.  A freshly fed active starter will suddenly smell like wet flour.  You want to add enough flour so that the yeast smell is gone. (if you are looking for some kind of value.)   When it peaks again, reduce and feed.  This can be rather tricky because it is possible to under or over feed.  

I have a standard by which I judge a starter's strength/yeast growth.  Take 15g of starter and combine with 150g water and 150g flour, mix well, pack neatly into a tall straight drinking type glass or measuring beaker, cover with plastic or foil, put a stripe of tape up the side, and mark the level.  I remove the marked tape to my notebook.  

I ignore it for the first 3 hrs of lag time.  (If it rises, it is bacterial and not yeast, discard all.)  I start marking the rise in hourly increments until it has peaked.  A new starter at 24°C takes about 8 to 12 hrs. to peak.  If it takes much longer it gets discarded and I wait another day or two for my week old starter seed to develop yeast (looking for a warmer spot) before testing again.   If the peak is under or around 12 hours, immediately repeat test until peak is at our about 8 hrs.   

Weigh the discard starter and mix up a nice 1:2:3 sourdough bread.  (1:2:3  S:W:F or starter:water:flour) 

Instead I keep it in the refrigerator and replace it entirely every 7 to 10 days by making extra when I bake, or enough to replace it entirely if, rarely, I don't bake sourdough bread within that time interval. I also keep a Rye Sour, replaced every 14 days using the same discipline. I keep both at 100% hydration.

I don't know if my starter is weak, strong or average. When I build levain for a bake I do it in three steps over 24 hours. When I first started with sourdough, four years ago, I wrote an elaborate blog on building "formula ready levain" with three builds and adjusting the starter's hydration by a third (up or down) to match the desired liquid or stiff levain called for. I confess, as time went on, and my comfort level handling sourdough increased, I began adjusting most formula's flour and water to allow using 100% hydrated levain. However, because the seed starter is stored in the refrigerator without feeding for the aforementioned time I still make levain in three eight hour builds. Routinely, I bake 2 or 3 sourdough loaves, or 3 or 4 baguettes, or a sheet pan of focaccia weekly: what ever it takes to keep the freezer stocked for the two of us. About twice a year, especially around Christmas, I go on a baking week-long baking marathon.

Build 1 usually begins with 40g of seed starter fed with 2:1:1 The reason I use 2:1:1 is I don't want to modify the seed starter's pH drastically. I don't know what it is, but I reason a smaller change of environment is better than a bigger change. Like clockwork, this mixture peaks (at room temperature) in 7 to 8 hours.

Build 2 I feed 40g flour and 40g water, which is again 2:1:1. Finallly, Build 3. I feed 80g flour and and 80g of water which is also 2:1:1.This yields 320g of ripe levain. I take 20g of the vigorous levain and feed it 1:1:1. This 60g I put into the seed starter's cleaned and sanitized container, and place it immediately in the refrigerator, ready for next week's bake. The remaining 300g are sufficient for one of my "go to" sourdough formulae, which includes three variations (10% rye, 50% WW and 5% rye and all in the high 60's % hydration), sourdough baguettes (which are 100% AP flour, 67% hydration), and focaccia (which is also 100% AP, 72% hydration, and some olive oil). If I require more levain I adjust the builds' feeding ratios, or add a fourth build.

I bulk ferment all these doughs at 54°F for 12 to 16 hours. I divide them (except for the focaccia) and warm them for 1 hour at 82°F. Proofing shaped, lean-dough loaves invariably takes 2 hours and 15 mins. at 82°F +/- 5 mins. The focaccia only proofs about 1 hour and 30 mins.

Bake-to-bake I get essentially the same adequate oven spring.

Room temperature is a constant 76°F during the spring and summer months, and 68°F to 72°F during January and February. (We don't have an autumn in Florida.) Nonetheless, I don't experience a large variability in peak times building levain. I proof all but the baguettes at 82°F in a proofing box.

Lately, I've been experimenting with fermenting the 3rd build at 82°F--the sweet spot for yeast growth--but I've not seen a significant difference so far.

Since I replace it entirely, weekly,  I won't claim any longevity for my seed starter, but I've been doing this discipline for the past two years with the same culture, and experiencing very satisfactory and consistent results.

David G

...wetter and warmer favors yeast, stiffer and cooler favors bacteria. Please let us know.

David G

or is it biology?    

If one feeds a starter only enough food to produce enough gas to double, then feed the starter more food.  More often than not,  if you feed it more, it can easily double and triple and quadruple.  Some flours will not allow for massive volume increases (like gluten free flours) others, like wheat (and a good glutinous one) can easily increase 5 times.  

The comparison of volume is always an interesting one.  

I have often seen a direct correlation in the amount of food.  Feed 10g of healthy starter 10 g of flour, it doubles.  Feed 10 g of starter 40g of flour, it quadruples with a little more time.  etc.  (water is added to make a paste or soft dough)  

Just by taking 20g of starter and giving it 20g of water the mass has doubled.  Give it 20g of flour (food) it has tripled in weight (but not quite in volume) but that is not what we really are talking about...   or are we? 

Once this 60g of starter is then placed in a narrow container and allowed to rise on its own in a warm environment, we expect it to double in volume.   I suppose that would be 6 x the initial 20g of starter.   Doubling would only be 2x we've already gone past that.  

We are interested chiefly in fermentation using various species of bacteria and yeast to do this for us.  We give them a food source so that they metabolize increase substantially in numbers releasing gas and other by-products.  These by-products first work for us giving us added flavour and a working window to raise and shape our dough then when they have built up, work against us eventually breaking down our dough so it can no longer trap the gas.  We want to achieve a risen loaf before the dough breaks apart or over proofs.  

Starters are no different and in fact small examples of the same process.  We just give them more flour and water when we want to increase their numbers.  A good concentration of yeast in the starter means we can raise our loaf fast enough to avoid over proofing.  

Over proofing can also happen if the flour breaks down before enough yeast are present to raise the loaf.  Bacteria are good at this and when the starter has too much bacteria to yeast ratio, the dough may taste great but yeast are unable to raise the loaf properly in time for the bake.  So it turns out to be a balancing act in not only maintaining a starter but in increasing the amount for use as well.  When you sense the yeast numbers are too low, your starter seems to work slower in spite of maintaining warm conditions for growth, then feed your seed starter to favour the yeast.  That would mean warm, more flour and more often. A certain amount of water is necessary for the yeast. I would not feed (the process of discarding & feeding) less than every 8 hours (23°C) in order to hang on to a certain number of bacterial.  

Maintaining a (seed) starter is to just keep a certain healthy population of bread slaves around without killing them or sending them into a catatonic state.  Inoculating flour, making flour "builds" in single or multiple steps is to increase yeast numbers and play with the flavouring.  The end result should be a consistent balance of desired yeast and bacteria for whatever bread you choose.   Many recipes have this building process built into the recipe.  

Recipes that call for small amounts of sourdough starter usually 10 to 30g (teaspoons) include instructions to build or increase the amount of starter or pre-fermented dough.  Recipes that call for amounts above 100g (cups) tend to assume you already have a built starter, one that has been fed and allowed to peak just before using.  Liquid starters (those made with equal volumes of flour and water or with more water than flour weight) tend not to rise, have bubbles, stored in large jars or buckets and use less recipe water and large portions of starter as the starter provides the liquid in the dough.