How Thai Shrimp Paste Is Made: A Visual Guide to Kapi

Thai shrimp paste, called kapi, is made by mixing tiny shrimp with salt, sun-drying the mixture, grinding it into a paste and leaving it to ferment. Many producers repeat the drying and grinding several times. The result is a dense, purplish-brown paste with a powerful aroma. Cooks use small amounts of it to give Thai dishes a deep, savory, sea-like flavor. Thai shrimp paste production depends on just two ingredients, shrimp and salt, plus sun, time and a lot of pounding.

What is kapi?

Kapi is a fermented paste made from very small shrimp and salt. It is one of the basic seasonings of Thai cooking. It is not eaten on its own. Instead, it acts like a flavor foundation, in the same way that anchovies or aged cheese add depth to Western dishes. A spoonful of kapi in a chili dip or curry paste adds savoriness, saltiness and a lingering ocean note that is hard to get any other way.

Kapi is especially associated with coastal areas of Thailand, where the small shrimp are caught close to shore. Different towns and family producers have their own styles. Some kapi is softer and lighter, and some is firmer, darker and more pungent.

Which shrimp are used to make Thai shrimp paste?

Thai shrimp paste is traditionally made from tiny, almost translucent shrimp, often only about the length of a fingernail. These are small krill-like shrimp, sometimes called kei in Thai, caught in fine nets in shallow coastal waters. They are far too small to peel. The whole shrimp is used, including shell, head and tail.

Fresh, the catch looks like a pale pinkish-grey mass. It smells clean and briny when very fresh. Freshness matters, because shrimp spoil quickly in tropical heat. Producers usually salt the shrimp soon after landing to stop spoilage.

How is Thai shrimp paste made, step by step?

Traditional Thai shrimp paste production follows a cycle of salting, draining, drying, grinding and fermentation. Exact salt amounts, drying times and the number of repetitions vary from producer to producer and are often kept as family know-how. The general sequence looks like this:

1. Cleaning and sorting. The fresh shrimp are rinsed. Bits of seaweed, small fish and debris are picked out so the paste has an even texture and clean flavor.
2. Salting. The shrimp are mixed thoroughly with coarse salt. The salt draws out water, slows the growth of spoilage microbes and starts flavor development. The mixture is often left overnight in baskets or containers so the excess liquid can drain away.
3. Sun-drying. The salted shrimp are spread thinly on mats, sheets or racks under the sun. Drying removes moisture and concentrates flavor. The color shifts from pale pink toward a deeper rosy-brown.
4. Grinding or pounding. The partly dried shrimp are crushed into a coarse paste. This was traditionally done with large mortars and pestles, and today it is often done with mechanical grinders. Grinding breaks up the shells and brings everything into a uniform mass.
5. Repeating the dry-and-grind cycle. Many producers spread the paste out to dry again and then grind it once more. Each round makes the paste smoother, firmer and more concentrated.
6. Packing and fermenting. The paste is pressed tightly into jars, clay pots or tubs to keep air out. It is then left to ferment, often for weeks to several months depending on the producer. During this time the flavor turns deeper, rounder and more pungent, and the color darkens.
7. Final packing. The finished kapi is packed into jars, plastic tubs or blocks for sale.

What happens during fermentation?

During kapi fermentation, natural enzymes in the shrimp and salt-tolerant microbes slowly break the shrimp proteins down into smaller compounds, including amino acids that taste savory, or umami. The high salt level keeps harmful spoilage in check while these slower, flavor-building changes take place.

This is why kapi tastes much more complex than simply salty dried shrimp. Fermentation adds a rich, meaty depth and the famous strong aroma. Fermentation is also what links kapi to fish sauce. Both rely on salt and time to turn seafood into a seasoning. Fish sauce becomes a clear liquid, while kapi stays a thick paste because it is dried and ground.

Why are drying and grinding so important?

Drying and grinding give Thai shrimp paste its dense texture and concentrated flavor. Drying removes water, which helps the paste keep for a long time and intensifies its taste. Grinding turns crunchy little shrimp into a smooth, spreadable mass. It also mixes the salt evenly and exposes more surface for fermentation to act on.

The balance between the two shapes the final style. Paste that is dried less stays softer and moister. Paste that is dried and ground more often becomes firmer, darker and stronger in flavor.

How do you recognize good Thai shrimp paste?

Good kapi is a thick, fine paste in a purplish-brown, greyish-mauve or dark brown color, with a strong but not rotten smell. Here is what to look and smell for:

• Color: Natural kapi ranges from dusky pinkish-purple to deep chocolate-brown. A shockingly bright pink or red color may point to added coloring, so a vivid color is not a sign of quality.
• Texture: It is dense and slightly sticky, a bit like firm clay or thick nut butter. It should be fairly smooth, though tiny shell flecks are normal.
• Aroma: Raw kapi smells intensely of the sea: salty, funky and deeply savory. Many first-timers find it startling. It should not smell sour, moldy or like spoiled shrimp.
• Packaging: It is usually sold in small plastic tubs or glass jars, and sometimes in wrapped blocks.

How is kapi used in Thai cooking?

Kapi is used in small amounts, often a teaspoon or less, to add savory depth to chili dips, curry pastes, sauces and fried rice. Here are some familiar examples:

• Nam prik kapi: a classic chili dip made by pounding kapi with garlic, chilies, lime juice, palm sugar and sometimes small eggplants. It is served with fresh or boiled vegetables and fried fish. Here kapi is the star flavor.
• Curry pastes: Many Thai curry pastes, such as red and sour curry pastes, include a little kapi. You will not notice it as shrimp. It simply makes the curry taste fuller and rounder.
• Khao khluk kapi: rice tossed or fried with shrimp paste, served with toppings such as sweet pork, shredded green mango, sliced shallots, egg and chilies.
• Dipping sauces and stir-fries: A small dab can deepen a sauce or a vegetable stir-fry.

Kitchen tools and preparation tips

The traditional tool for working with kapi is the Thai mortar and pestle, called a krok, which is often made of granite or clay. Pounding kapi together with garlic, chilies and herbs blends it evenly into a paste or dip.

• Toast it first for a mellower flavor. Many cooks wrap a small piece of kapi in banana leaf or foil and warm it in a dry pan or over a flame until it smells toasty. This softens the raw sharpness and brings out a roasted aroma. Expect a strong smell in the kitchen while you do this.
• Start small. Kapi is very salty. Add a little, taste, and then adjust the other salty seasonings, such as fish sauce, accordingly.
• Store it airtight. Keep kapi in a well-sealed jar so its aroma does not spread through the fridge or pantry. Because it is salted and fermented, it keeps for a long time, but it should be thrown away if it develops mold or an off smell.

How does Thai kapi differ from similar shrimp pastes and fish sauce?

Thai kapi belongs to a family of Southeast Asian fermented shrimp products. They are made in similar ways but differ in texture, form and how they are used. Fish sauce is related but is a liquid usually made from fish rather than shrimp.

Product	Typical form and look	How it is commonly used
Thai kapi	Soft to firm paste, purplish-brown, usually sold in tubs or jars	Chili dips, curry pastes, fried rice, often pounded in a mortar
Malaysian belacan	Usually drier, pressed into firm blocks, dark brown	Toasted and crumbled into sambal and stir-fries
Indonesian terasi	Firm blocks, brown to reddish-brown	Toasted and ground into sambal and spice pastes
Filipino bagoong alamang	Wetter, chunkier paste, often pink, sometimes sold sautéed	Eaten as a condiment, for example with green mango, or cooked into dishes
Thai fish sauce (nam pla)	Clear amber-brown liquid made from fermented fish and salt	All-purpose salty seasoning in soups, dressings, stir-fries and dips

The key difference is that kapi is dried and ground into a paste, while fish sauce is the liquid drawn off from fermented fish. Kapi brings a thicker, earthier, more pungent depth. Fish sauce brings a cleaner salty-savory note that spreads easily through liquids.

What can you use instead of Thai shrimp paste?

The closest substitutes for Thai kapi are other Southeast Asian shrimp pastes such as belacan or terasi. Every substitute changes the flavor somewhat:

• Belacan or terasi: These are the nearest match in flavor. They are usually drier and firmer, so crumble or toast them and use a little less at first.
• Fish sauce: This adds salt and umami but lacks kapi's thick, funky depth and its paste-like body. It works best in curries and sauces, not as a replacement in nam prik kapi, where shrimp paste is the main flavor.
• Anchovy paste: This gives a similar salty, savory sea note, but the flavor is fishier and less shrimpy.
• Miso or fermented soybean paste (for a vegetarian option): This provides savory depth and saltiness but no seafood character. The dish will taste noticeably different.

For dishes where kapi is only one of many ingredients, such as curry pastes, a substitute can work reasonably well. For dishes built around it, like nam prik kapi or khao khluk kapi, real Thai shrimp paste is worth seeking out at an Asian grocery store.