Acidic/Vinegary starter? How to adjust?

Yes, you can vary the hydration in your starter: more stiff starter will need more time to rise and develop a stronger flavour. But there is much more you can adjust:

What kind of flour do you use?
For baking spelt or wheat bread you might want to switch to a wheat or spelt starter as they usually are much more mild than the usual rye starter. (You can seed a wheat starter with your rye starter).

What is the temperature while feeding?
About 25 °C (77°Fahrenheit) is perfect for the wild yeast. Below this temperature you will get a more vinegary taste; above more lactic acids (the mild, flavourful ones) will be developed. Of course, always all 3 things will happen, but the proportions differ with the temperature.

If the vinegar smell gets very strong, it might be that the MOs are already starving. How long do you keep it on room temperature until you put it back into the fridge? (of course this depends on how vivid your starter is, the temperature, the hydration and your feeding ratio). I feed mine 1:2:2 and put it back directly after it peaked at 4-5hours.

just taking a small amount of it and feeding it equal parts of flour and water and doing the same thing again, after it doubles 4-6  hours later, will usually do the trick and remove excess or unwanted sour.

Take 20 g of starter, 20 each of flour and water making 60 g then,  when it doubles take 30 g of it and add 30 g each of flour and water and let it double again.  This gives you 90 g of not so sour starter.

You can bake with 20 g of it by building a 3 stage levain over 8-12 hours to what ever amount of levain you need (or some other way like a 2 - 6 hoiur builds) and then thicken up the remaining 70 g by adding 25 g of flour and 5g of water to it - making it 100 g at 66% hydration starter, letting it rise 25% and then refrigerating it for use over the next 3-4 weeks.

Happy baking

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