Beer Forum

OK! so I stepped up a yeast starter from 500 ml to 1000 ml after finding an old expired vial in my fridge. The 500 ml barely took off. When I stepped it up to 1000 ml, it lagged for a day and then went off. It krausened over the top yet still under the foil. It had dried but I lifted the foil back, wiped up as much as would come off with isopropyl. then I switched the foil with a new foil piece that had soaked in starsan. Am I good or is it toast after coming out the sides? Do bacteria crawl up dried krausen bits, under foil, and into starters?

SoCal Surfer wrote:OK! so I stepped up a yeast starter from 500 ml to 1000 ml after finding an old expired vial in my fridge. The 500 ml barely took off. When I stepped it up to 1000 ml, it lagged for a day and then went off. It krausened over the top yet still under the foil. It had dried but I lifted the foil back, wiped up as much as would come off with isopropyl. then I switched the foil with a new foil piece that had soaked in starsan. Am I good or is it toast after coming out the sides? Do bacteria crawl up dried krausen bits, under foil, and into starters?

Bacteria doesn't crawl (no legs). They ride on the dust and flying/crawling insects. I'd say unless you found fruit flys or spiders or something in there you're good to go.

+1 most likely good to go. Besides with all of your yeast in there raging on the wort there really would be very little chance for any other populations of critters to get started. next time add a drop of foam control to keep the krausen under raps.

i think you're fine, smell it and see if it smells out of the ordinary

jm wrote:Bacteria doesn't crawl (no legs). They ride on the dust and flying/crawling insects. I'd say unless you found fruit flys or spiders or something in there you're good to go.

New studies have shown that bacteria are able to walk around on surfaces http://www.sciencedaily.com/releases/2010/10/101007171424.htm, however, for the size scale you are dealing with, the movement of those bacteria is going to be in such a small distance it's not an issue. As JM notes, it's mainly fruit flies that can bring bacteria and wild yeast into a starter.

spiderwrangler wrote:

jm wrote:Bacteria doesn't crawl (no legs). They ride on the dust and flying/crawling insects. I'd say unless you found fruit flys or spiders or something in there you're good to go.

New studies have shown that bacteria are able to walk around on surfaces http://www.sciencedaily.com/releases/2010/10/101007171424.htm

Wild stuff.

spiderwrangler wrote:

jm wrote:Bacteria doesn't crawl (no legs). They ride on the dust and flying/crawling insects. I'd say unless you found fruit flys or spiders or something in there you're good to go.

New studies have shown that bacteria are able to walk around on surfaces http://www.sciencedaily.com/releases/2010/10/101007171424.htm, however, for the size scale you are dealing with, the movement of those bacteria is going to be in such a small distance it's not an issue. As JM notes, it's mainly fruit flies that can bring bacteria and wild yeast into a starter.

This is true evidence of evolution continuing to happen even in our lifetime! CRAZY!!

It may also just be behavior that hasn't been observed before...