From what i've read..
has a massive bag
There's these guys
, but i've never heard of them.. Third paragraph though.
A couple excerpts from this article
"Untoasted oak is a rich source of hydrolysable tannins called ellagitannins, which break down in must to yield prodigious quantities of gallic acid, a powerful cofactor. The toasting process turns these useful small molecules into large polymers that won't form colloids. Toasted wood doesn't work to enhance color extraction. Worse, the barbecue aromas of toasted wood are amplified by yeast action to produce a strong Worcestershire aroma."
"Wines containing vegetal or microbial notes often can benefit from enhanced structure, which can serve to integrate these aromas into the background and allow them to merge with and support fruit character. Oak can be used to assist this process in several ways already discussed, such as anthocyanin extraction and structural supplementation. Oak introduced during primary fermentation can also provide sacrificial tannins that remove protein and deactivate yeast enzymes destructive to color. Structural enhancements call for extra wood, usually in the form of highquality, untoasted oak chips."
I cant really back up the information, but from what i've gathered;
It's added during primary fermentation of white (and im assuming fruit wines here, my line of thinking) to add structure and help negate some volatile acids (still trying to figure out the how on this), enhances the fruity profile of the given wine, stabilizes the color of the wine over time, without lending a lot of the characteristics found in toasted oaks - the spice/leather/smoke in heavy toasts or the caramel/vanilla/..oak? in medium toasts..
Still looking for more information myself..