Belacan is a fermented shrimp paste made from krill and salt, and it serves as a foundational ingredient in Malay and Peranakan cooking. Dense, pungent, and packed with umami, it works as a flavor base in curries, stir-fries, and the beloved condiment sambal belacan. If you’ve encountered it for the first time, the smell can be startling, but that intensity is exactly what makes it essential in Southeast Asian kitchens.
How Belacan Is Made
The ingredient list is short: tiny shrimp (specifically krill, called geragau in Malay) and salt. The process, however, takes weeks. Fresh krill are first washed in seawater, then semi-dried on mats or wooden racks along the beach. Once partially dried, the krill are mixed with salt at a ratio of roughly 3 kilograms of salt per 60 kilograms of krill, then ground through a meat grinder and dried again for about a week.
This cycle of grinding and sun-drying repeats multiple times over several weeks until the paste reaches the consistency of soft clay. The mixture then ferments in earthenware pots, gradually shifting from pink to a deep reddish-brown. Once fermentation is complete, the paste is pressed into thin rectangular blocks or circular discs, dried in the sun one final time, and wrapped in paper or plastic for sale. The salt concentration in the finished product is high, roughly double that of cincaluk (another Malaysian fermented shrimp product), which is what gives belacan its long shelf life and intense flavor.
What Happens During Fermentation
Belacan’s complex flavor comes from salt-loving bacteria that thrive in the paste’s high-salt environment (typically 25 to 35 percent salt by weight). These microbes break down proteins in the shrimp into amino acids, which is the source of the deep umami taste. Some species also have fat-breaking abilities that contribute to belacan’s distinctive aroma.
One group of bacteria commonly found in fermented shrimp pastes has been shown to enhance amino acid production without generating histamine, a compound that can cause headaches or allergic-type reactions in sensitive people. Other species found in some batches, however, do produce histamine and similar compounds. This variation depends on the specific microbes present, which differ from producer to producer and batch to batch. Traditionally made belacan, without standardized starter cultures, will always have some natural variability in its microbial makeup.
Belacan vs. Other Shrimp Pastes
Shrimp paste exists across Southeast Asia under different names, and the differences between them are subtle but real. In Thailand, it’s called kapi. In Indonesia, it’s terasi. All share the same basic concept of salted, fermented shrimp, but they vary in moisture, texture, and intensity.
Malaysian and Singaporean belacan tends to be dry and firm, sold in hard blocks that you can slice or break off in pieces. Thai kapi is often softer and wetter. Indonesian terasi falls somewhere in between and sometimes has a slightly different color depending on the shrimp species used. For cooking purposes, these pastes are largely interchangeable, though cooks who grew up with a specific version will notice the difference in saltiness and depth of flavor.
How to Use It
Belacan is almost never eaten raw. The most common preparation is to toast or dry-roast a small piece over an open flame or in a dry pan until it darkens slightly and becomes fragrant. This step mellows the raw pungency and brings out a nuttier, more rounded flavor. The toasted paste is then pounded in a mortar with chilies, shallots, and lime juice to make sambal belacan, the fiery condiment served alongside rice, vegetables, and grilled fish.
Beyond sambal, belacan works as a background seasoning in dozens of dishes. A small amount stirred into a curry paste, fried rice, or soup broth adds a savory depth that’s hard to replicate with other ingredients. A little goes a long way. Even a piece the size of your thumbnail can season an entire pot.
Storage and Shelf Life
Belacan’s high salt content acts as a natural preservative. An unopened block stored in a cool, dry place keeps well for months. Prepared dishes made with belacan, like sambal belacan, have a shorter window of around six months at room temperature, though proper packaging and storage conditions can extend that to about a year.
Once you’ve opened a block, wrapping it tightly in plastic and storing it in the refrigerator is the best approach. The paste will continue to develop in flavor over time but won’t spoil easily. The biggest practical concern is containing the smell: double-wrapping or using an airtight container keeps your fridge from absorbing the aroma.
Shellfish Allergy Concerns
Belacan is made entirely from crustaceans, so it poses a serious risk for anyone with a shellfish allergy. The primary allergen in shrimp and other crustaceans is a protein called tropomyosin, which is found across invertebrates including shrimp, crab, lobster, and even dust mites and cockroaches. This means cross-reactivity is possible for people sensitized to any of these sources.
Because belacan is sometimes used as a hidden ingredient in curry pastes, chili sauces, and pre-made spice blends, it can be easy to consume unknowingly. If you have a crustacean allergy, checking ingredient labels on Southeast Asian sauces and condiments is important. Shrimp paste may also appear listed as “shrimp paste,” “prawn paste,” or under its regional names (belacan, terasi, kapi) depending on the product’s country of origin.