Flavor – What makes a ‘primary’ taste

Beer is made from malted cereal grains. These can be corn but more commonly malted barley. The malting process turns the starch in the grain into sugars then the fermentation turns the sugars into beer. To get a strong dry beer, first start with a sweet malt and the ferment until as much sugar as possible becomes alcohol. For a non alcoholic beer, you need to remove the alcohol so you start with a low sugar malt and ferment just long enough to get the flavour but not too much alcohol. Since the fermentation is short, even through the initial sugar content might be low, there is sugar left in the beer thus giving you a sweet taste.

Short answer: Steam.

Long answer: Proteins in egg whites are almost uniquely suited to making foams of tiny bubbles, then stretching like a web of bungee cords as the water inside these bubbles turns to steam in the oven. Therefore, the critical element in making your souffle rise is the skill with which you whip the whites into a foam to the correct degree (just to stiff peaks, not over-whipped), followed by integrating (folding) that foam into the dense, flavor-filled base. There are a few tricks for augmenting the rise -- e.g., using a pinch of tartaric acid in the whites, using a copper bowl -- but if your technique is poor, these things won't make enough of a difference.

Alton Brown ("Good Eats" TV show) has an excellent program explaining the whole thing, including some basic chemistry, available free on YouTube: Part 1 Part 2

By the way, you said that a successful souffle must rise above the vessel. While rising high is a major goal, I would not limit success to that event. Last night, I made chocolate souffle that only crested the vessel a little ways (not the ideal "double the volume"), but each bite was still ethereal and decadent at the same time. Everyone's plate was clean. THAT, to me, is a successful souffle.