I have a fridge stored starter. I got it from a class, and maintained it for months, but I didn't have a regular feeding schedule. I'd feed it a couple of tablespoons of flour and water every now and then. Recently when I use it, the leaven doesn't seem to rise and ferment as much, and the bread had an "undercooked" inside, even though it rose normally during the baking process.
It's been a lot colder recently and I'm wondering if I simply need to give the leaven more time to rise before using it? The house temperature is usually between 60-65 degrees. Previously I'd let my dough rise overnight or all day and it would gain a fair bit of volume but recently has not.
Is there a test if the starter is still active?