Yes, there is a long history of egg whites being used in France, primarily for polishing rough tannins in red wine. I experimented using them a few times in my early wine-making days, but for me they aren't necessary, as I like some good astringency in my wine.
Yes, there’s also enzymes derived from egg whites that are pretty popular as well. Added at different stages will have different benefits. But mainly for improving microbial control. Deals mainly with lactic acid I believe.
And has to do with the effecting other gram positive bacteria. That’s about as scientific as I currently understand it.
Lactizyme and lysozyme are associated/derived? From egg whites.
Looks like egg whites are used for resolving overly tannic wine while being gentle on color. I've used gelatin when the need arose for this purpose.
I haven't used egg whites personally but these instructions are from Pambianchi's book.
"... 1-2 egg whites per 100L. First separate the egg white from the yolk, discard the yolk and then add to slightly salted water. Salt prevents the solution from getting cloudy. Alternately, use pure, refrigerated egg whites, the type sold in small cartons in your grocer's dairy section. Typically, approximately 30mL (2 tbsp) of pure egg white is equivalent to 1 large egg white. For each egg white, dissolve a pinch of salt in 100mL of water and then combine with the egg white. Add the saline egg white solution to the wine directly into the barrel and stir gently but thoroughly. Rack the wine in 1-2 weeks, no later."