What You Need to Know
Under reduced pressure, water evaporates at ~50 °C, lowering the effective temperature of the food matrix. Sugars such as sucrose and glucose undergo dehydration, isomerization, and polymerization at 120–140 °C, forming caramel color compounds and flavor aldehydes. The limited oxygen exposure suppresses Maillard browning and oxidation of phenolics, yielding a smoother, less bitter profile.
The Science
Primary Reaction
Caramelization of sucrose and glucose under reduced pressure