If the oxidation of glucose can produce flames, as seen when roasting a marshmallow over a campfire, why don't we risk internal burns when we swallow a marshmallow and oxidize its glucose with cellular respiration?
The lining of our stomach prevents burning food from causing damage to our bodies.
Oxidation is not taking place. The marshmallow is being reduced.
Digestion of the marshmallow is an endergonic process, therefore, no energy is released.
Cellular respiration releases the energy from the glucose in small increments, rather than all at once.