Propylene Glycol?

So, I am putting together the clone recipe from the BYO book for Young's Double Chocolate Stout. It calls for .33 oz. of Chocolate Extract (or Essence . . . or something). The only thing that I can find are these little bottles of flavoring I found at a cake decorating shop. This product contains propylene glycol.

My questions:

What is it?
Is it an oil?
If I add this amount, will it kill my beer's head retention, etc.?
What are some alternatives?

The recipe calls for powerdered cocoa . . . can I just add some extra rather than this flavoring?

I need advice from those of you who have made choco stouts successfully.

Thnx

Propylene glycol is used as a solvent in flavorings/extracts (similar to alcohol, but cheaper).

You can find good quality chocolate extract at Williams-Sonoma. If I recall, it is about $12 for a bottle, but it lasts a long time. It is what I used in my chocolate stout.

Propylene glycol is also used as for its high boiling point. Extracts made with it don't dry out as quickly as alcohol-based ones. It won't hurt your stout.

I'd just increase the cocoa powder. Use dutch-processed powder if you can get it. It stays in suspension better.

I'm really curious to hear how this turns out for you, I've been eyeing that recipe for some time. Young's Double Chocolate is one of my favorite beers, and will probably be the first thing I brew if I ever come across a Nitrogen setup on the cheap.

Actually this is funny, I was just now looking through my copy of BYO's 150 clone recipes and for ideas on my second AG and was telling SWMBO that I thought the Youngs looked good. That or Widmer Bros Snowplow Milk Stout. Great minds and all that.