Adding yeast during 2nd fermentation

Good evening from a very stormy UK.

I've been doing some reading on larger brewing and
Found out some info.

Apparently whilst it's in its secondary fermentation ( bottled) to insure
Good head retention you can add a very small amount of yeast.

Is this true?
Also is the anything else you can add at this point. I've heard about adding citrus acid too. ?
Cheers guys

Yeast don't directly contribute to head retention, it's primarily the percentage of residual proteins in the beer (and lack of lipids). I can't think of any reason extra yeast or citric acid would help.

If your beers are struggling with head retention as a general rule, the correct way to combat it is to add about 5% of the total grain bill in CaraPils malt. That adds extra residual proteins that create and maintain head on a beer.

Now, the better question is why are you having trouble with head retention in the first place? As long as the beer is properly carbonated, they should be fine.

Maybe outline your process with this latest batch so we can see if anything stands out?

Instead of adding for head retention think about taking something away. One of the major problems with head retention is residual soap and anti-spot agents in the glass. Another one is adding oil to the glass by the use of lip balm.

The two big problems of head retention are clean glassware (no rinse aids!) and insufficient carbonation. The longer you let your bottles condition, the better the head will be. If you've got any crystal malts in your beer at all, you should have decent head with a properly carbed beer and clean glass.

If you add yeast during secondary (usually totally unnecessary, but that's another discussion), you will get..............................yeasty beer.

When you say "larger brewing" do you mean high gravity, or is it a typo and you meant lager?
If you meant high gravity, another problem may be fusel alcohols from a suboptimal fermentation which have supposedly been implicated in ruining head retention.