Kapi — fermented shrimp paste — is the foundational umami ingredient of the Thai kitchen. Made from small shrimp (krill) fermented with salt for 3–6 months and sun-dried, kapi ranges from liquid and pale (fresh, mild) to solid and dark brown-black (aged, intensely flavoured). Every Thai curry paste includes it; nam prik kapi (Entry TH-07) is built around it; many soups and sauces use it as a background seasoning. Thompson considers kapi's quality one of the most important variables in Thai cooking — a high-quality shrimp paste contributes a complexity and depth that elevates an entire preparation; a poor-quality or improperly stored paste adds only an acrid, one-dimensional fishiness.
**Quality indicators:** - Colour: medium to dark brown — not black (over-fermented or burnt in processing) and not pale grey (under-fermented, lacking complexity). - Smell: intensely marine, complex, deep — the smell of the sea at low tide combined with a slightly funky, yeasty note. Not ammonia-sharp (ammonia indicates spoilage or very low quality). Press the block and smell: fresh kapi from a freshly opened container smells of concentrated, complex fermented shrimp; aged (open container, exposed to air) kapi develops an edge. - Texture: should be dense, slightly sticky, and moldable — not crumbly (too dry) and not liquid. **Brands:** [VERIFY] Thompson's specific brand preferences from the source text. For professional kitchen use in North America: Pantainorasingh and Tra Chang are considered reliable quality brands available through Asian grocery importers. **The roasting step:** For many preparations (nam prik kapi, certain curry pastes), Thompson roasts the kapi before use — wrapping in foil and placing over a gas flame or under a grill for 3–5 minutes per side. Roasting moderates the raw ammonia edge of the fermented shrimp, adds a caramelised Maillard depth to the surface compounds, and produces a slightly drier, more concentrated paste. The roasted kapi's smell: complex, slightly smoky, deeply savoury — dramatically different from the raw paste. **For curry pastes:** Some recipes roast the kapi before pounding it into the paste; others add raw kapi. Thompson specifies which for each paste. [VERIFY] his specific instructions for each paste entry.
David Thompson, *Thai Food* (2002); *Thai Street Food* (2010)