Making caramelized onions involves both the Maillard reaction and caramelization, and these are two distinct processes. The Maillard reaction is when amino acids or proteins react with sugars to produce browning and a broad range of savory, roasty, nutty, and complex flavors. This reaction is important in browned meat, toast, and bread crusts. Caramelization on the other hand is a reaction involving the thermal breakdown of sugars alone, and it creates flavors that are best described as like, well, caramel. The flavor of properly caramelized onions relies on both of these reactions, and while baking soda can speed the Maillard it does nothing for the caramelization reaction. For this to occur, there is no escaping the long cooking of the traditional method. And without caramelization, the result will just not taste as good! They are, after all, called caramelized onions!
