I have had a starter which i've been using regularly, quite successfully for about 4 years.
recently however its started to really lose its strength; its not doubling in size when i feed it (plain flour) and its not rising my breads. It has a small bit of action, but only a fraction of what it was.
does anyone know what could be causing this or how i could remedy it? Its got a really great flavour to it so i'd love to not lose it.
A lot of people use an addition of wholemeal rye flour to their culture feed. Rye flour reportedly contains a beneficial enzyme and wholemeal flour carries more wild yeasts on the bran etc than white flour.
I use it at 5% of the flour in what I feed to my culture but I use only white flour for my loaf starter build. If I want a particularly white result, I build the loaf starter in stages from a very small amount from my stock so that the amount of rye present is very small.
Good luck with your projects.
I had a similar problem recently. I've been using the same starter for several years and it has always performed well but a few weeks ago it seemed to lose enthusiasm for life . My preferment looked nice and bubbly but bulk fermentation did not rise well and, despite longer proof period the eventual loaf was rather flat with a close crumb.
I always keep a few flakes of dried starter in the freezer against emergencies and, although these were over a year old, they restored well and after about a week I had a batch of starter that worked fine.
The trouble with sourdough is that, being an entirely natural product it can suffer the vagaries of, well, Nature: changes in humidity, different microflora floating about or differences in a batch of flour.
Things you might try:
Take a small quantity of starter and feed it intensely for a week or so
Try feeding it with mixed grain (I use 60g white flour, 30g wholemeal wheat and 10g rye)
Try keeping it in a different place
Try a fresh batch of flour for your next loaf
Sourdough baking is not an exact science. I try hard to maintain identical conditions for all my loaves (I even have a homemade proving cabinet) but I still find variations of as much as an hour in proving time, for which reason I have reverted to the "poke" method rather than timing.
Let us know if you solve the problem (and how)
White flour tires sourdough real fast, especially in warm weather, stick to wholewheat flour,