Marshmallows - effect of different ratios of corn syrup/sugar/gelatin?

Oh, AJ! Aren't you glad you got a stand mixer? They are a MIRACLE! Don't know how I'd live without...

With regard to "chocolate", I've actually made what I Cocoa Marshmallows (that taste just like hot chocolate, without burning the roof of your mouth!) by adding chocolate extract at the end (flavoring stage) and rolling the final product in a mixture of 1/3 cocoa- 2/3 powdered sugar. Total YUM!

This is an interesting question! I've just started making marshmallows, since buying my first ever stand mixer last fall. I have had the most success when the flavoring was in solid form, e.g., ground chocolate added at the very end, after the 15 minutes or so of beating at high speed. I did something similar to make peppermint marshmallows, adding a 1/8 teaspoon of high quality peppermint extract and ground up candy canes that I'd blitzed for about three minutes in a food processor with a bit of superfine sugar. I swirled that pink peppermint sugar in at the very end. I love the Cinnamon Chocolate Swirl marshmallow recipe here on FOOD52, by the way. My darling sister made a batch and sent them to me shortly after the recipe was posted, and the ability to make marshmallows like that is actually what (finally) tipped the balance, making me decide to get a stand mixer. ;o)

Well, I don't know the science, but here's what I've learned over the years: any flavoring with oil will have a "deflationary" effect on your product. It won't be flat, but it won't have the height that something flavored with an alcohol based extract will have. I haven't tried to flavor with actual alcohol, but know that a small, flavoring, amount (like a teaspoon or two) has an almost negligible effect -- if you're trying to flavor with more alcohol (like to make a rum flavored marshmallow with actual rum), it probably breaks up the gelatin --not sure that adding more will get you a better result. With regard to fruit, it is probably all the extra water (I tried flavoring marshmallows with fruit jelly because it already has the water tied up by sugar in the jelling process -- and found that I needed an unreasonable amount to get a real flavor impact -- again, a fruit extract or oil is a better bet, although see above for "deflationary" effects of oil). BTW: I found the same was true for food colors -- to have the impact I wanted, I had to add (what I considered) an unreasonable amount of color. One thing I do know -- the temp of your base will impact the gooey-ness of your product. Hard ball gets you a very firm marshmallow; soft ball gets you puffy magic.

So, I don't know the answers you're looking for, but hope that helped a bit.