« on: September 23, 2013, 09:25:41 AM »
I think the intention of the other comment was more like this. If you're brewing specifically to grow yeast for a big beer, and having a drinkable starter is a secondary goal, then removing simple sugars is a good idea. Ideally, a starter would be low OG so as to not stress the yeast. It should also be all malt because malt contains nutrients that yeast need to stay healthy. Simple sugar provides no nutrients and raises the OG. Both of these will stress the yeast and so it does not serve your primary goal.
So... I did not answer your question...
I think top-cropping is different in a few ways. Yeast is being removed at peak activity and put directly into fresh wort. The yeast have not yet had to attenuate those last bits of sugar in a high alcohol environment which is probably most stressful. Also, top cropped yeast at a brewery is likely to go into similar OG wort, not a higher OG wort, and the higher OG wort makes healthy yeast more important. Maybe the biggest difference may be goals though. A pro brewery wants beer first. Reusable yeast is a secondary goal and there may be some sacrifices being made to produce beer. Many US breweries reuse yeast after fermentation too, and I'm sure many of them use simple sugars.
So I guess the answer is that you can use simple sugars when repitching/harvesting/top cropping yeast. It's not the best choice, but it won't ruin your beer either. Seems like most decisions in brewing are not between great / ruined beer - just between better / not as good.
I probably made that more complicated than it needed to be.