Kapi — fermented shrimp paste — is one of the three fundamental fermented seasonings of the Thai kitchen (with fish sauce and fermented fish preparations). Made from small shrimp (krill or tiny prawns) fermented with salt for several weeks to months and then sun-dried to a dense, dark paste. Its flavour contribution is not merely salt: the fermentation produces an extraordinary concentration of glutamic acid, inosinic acid, and trimethylamine compounds that together provide the umami depth that underpins almost every Thai curry paste and many relishes.
**Quality indicators:** - **Colour:** Dark purple-brown to nearly black — the correct colour of well-fermented kapi. Light pink or pale grey kapi has been insufficiently fermented. - **Smell:** Pungent, intensely marine, complex. There should be a fermented depth beneath the sharp surface smell — not merely sharp and ammoniac. The smell should be assertive but not one-dimensional. Poor quality kapi smells of ammonia without the fermented complexity. - **Texture:** Firm, dense, slightly crumbly. It should hold its shape when a piece is broken off but not be hard or dried. **The roasting step:** Most Thai preparations that use kapi call for it to be roasted before use — this step is covered in Entry TH-07 (nam prik kapi) but applies universally. Wrap the required amount of kapi in a small piece of foil. Place in a dry pan over medium heat for 3–4 minutes per side, or hold directly over a gas flame. The kapi inside will heat, dry slightly, and develop Maillard products on its surface — the sharp raw fermented note moderates and a deeper, roasted complexity develops. **Usage in curry pastes:** Added last in the pounding sequence (Entry TH-01) — after all other ingredients are pounded to a smooth paste. The kapi's moisture and fermented compounds change the paste's texture and flavour from the moment of addition; adding it early prevents the other ingredients from pounding to their correct smoothness. **Storage:** Kapi stores at room temperature in an airtight container for 6 months. It does not require refrigeration — its salt content is a sufficient preservative. Refrigeration does not harm it. **Brands:** [VERIFY] Thompson's specific brand recommendations. Generally: Thai kapi is considered different from Indonesian terasi and Malaysian belacan — all are shrimp pastes, all have distinct flavour profiles reflecting different shrimp varieties, salt ratios, and fermentation times. Thai kapi is typically used for Thai preparations; Malaysian belacan is not a direct substitute.
David Thompson, *Thai Food* (2002); *Thai Street Food* (2010)