From what I have read, the typical timeline is to make your yeast start 24 to 48 hours in advance of brewing. I made mine last night with the intent of pitching it on Saturday morning. Will the starter be okay if I keep the covered flask in the fridge?
Maybe a better question is: What is the risk in making your starter further in advance?
If your starter is covered in the fridge and your sanitation practices are sound, there is no disadvantage to making it in advance.
There are two schools of thought concerning starters. The first is to make it 12 to 24 hours in advance and pitch it in your wort at high krausen while the yeast are most active. The second is to make it a few days in advance. After the starter has reached high krausen, chill it in the fridge until it is needed. By that time, the yeast will have settled to the bottom. You then pour off most of the liquid and pitch the yeast into your wort.
There are advantages and disadvantages to both methods. The idea of making a starter is not just to have enough healthy yeast but also to minimize the off flavors produced by yeast reproduction. The first method pitches your yeast when they are active and hungry but you also add your not so tasty starter to your beer. In the second method your starter won’t alter the taste of your beer. However, the yeast have gone dormant due to being chilled so your lag time will be longer than the first.
+1 for what Scottieboy said.
I do both methods. Just kinda depends on how I’m feeling, the yeast I’m reusing, the beer I’m making, etc. The lag time for yeast that you did days ahead of time usually isn’t much longer. The yeast is still very healthy. If the yeast I’m using is questionable (old yeast, shipped in hot weather, etc), I’ll do the starter days early, just to make sure it’s OK. I don’t want to make a starter the night before, and have it not ferment, and then not have yeast ready for the next day.
Your starter should last at least 1-2 weeks in the fridge.
Thanks all for the detailed responses. Very helpful!
I prefer to make a starter one weekend, brew the next. Give the yeast 3-4 days to multiply and ferment. 3-4 days in the refrigerator to drop out.
I try to go with at least 3-4 days before I plan to brew. I put it in the fridge the night before and then pull it back out when I begin brewing. YMMV.