What You Need to Know
During heating, sucrose dissolves in the wine and the mixture is reduced, concentrating sugars and flavors while ethanol evaporates as the temperature approaches its boiling point (78 °C). Spice essential oils such as cinnamaldehyde and eugenol are extracted efficiently between 50–70 °C, imparting characteristic aromas. If the temperature exceeds ~90 °C, sucrose undergoes caramelization, producing bitter notes, whereas insufficient heat leaves undissolved sugar and a gritty texture.
The Science
Primary Reaction
thermal evaporation of ethanol and water coupled with dissolution of sucrose and extraction of volatile spice compounds