Why can I disturb a starter but not the wort?

[petrolSpice]

Made my first starter today, WLP002 English Ale in a 1.6L 1.035 OG wort. Why is it okay to continuously shake/stir a starter, but not okay to disturb wort that is actively fermenting?

 

[rodwha]

The starter isn't properly aerated, and needs the oxygen shaking adds, which is minimal to what's needed, which is why it needs to be done several times.

 

[Facinerous]

Starters are meant to create a higher yeast cell count and optimal yeast health. Shaking the container with the starter keeps the yeast in suspension and helps keep oxygen in the liquid.

Once fermentation has started in your primary, introducing more oxygen to the wort will promote oxidation of the finished beer. On the other hand "disturbing" the wort such as moving the container, or even rousing the yeast from the bottom is not bad. Your goal would be to do so by keeping oxygen out of the container though. So keeping the lid on is your best bet.

Aside from that disturbing the container you are fermenting in will cause the sediment on the bottom to become suspended again, which could be considered bad by many brewers who want clarity in their beer once bottling/kegging.

 

[thisisbeer]

Adding oxygen to the wort can lead to off flavors. Starters are just to grow yeast and flavor doesn't matter. Thats why they can be fermented warmer and shaken to add o2.

 

[apalke]

Usually it doesn't matter if you oxidize the "beer" made by the starter since most people will cold crash their starter and decant the "beer" leaving the yeast which has settled to the bottom.

However, you definitely don't want to introduce oxygen to your real Beer after the initial stages of fermentation or you'll end up with off flavors due to oxidation.

 

[b-boy]

Since I throw out 90% of the wort from a starter, it doesn't really matter what I've done to it.

 

[rodwha]

I toss my whole starter in...