What You Need to Know
The preparation involves heating lemongrass and kaffir lime leaves to 80–90 °C to volatilize essential oils such as citral and limonene, simmering chilies for 10–15 min to extract capsaicin, and acidifying the broth with lime juice to lower the pH to ~4.5, which inhibits bacterial growth. Fish sauce added at 90 °C integrates umami peptides and salt, while shrimp cooked for no more than 3 min prevents protein denaturation that would otherwise produce a rubbery texture.
The Science
Primary Reaction
Extraction of essential oils, capsaicin, and aromatic compounds by heat; acidification to inhibit bacterial growth; protein denaturation at high temperatures.