Budu (Malay language) is a fish sauce and one of the best known fermented seafood products in Kelantan, Malaysia as well as Southern Thailand. It is traditionally made by mixing fish and salt in the range of ratio of 2:1 to 6:1 and allow to ferment for 140 to 200 days. It is used as a flavoring and is normally taken with fish, rice and raw vegetables.
It is similar to the patis in Philippines, ketjap-ikan in Indonesia, ngapi in Burma, nuoc mam in Vietnam, ishiru or shottsuru in Japan, colombo-cure in India and Pakistan, yeesu in China and aekjeot in Korea.
The fish product is the result of hydrolysis of fish and microbial proteases. The flavor and aroma of Budu are produced by the action of proteolytic microorganisms surviving during the fermentation process. Palm sugar and tamarind are usually added to promote the browning reaction occur and resulting in dark brown color. The ratio of fish to salt plays an important key in the final desired product. The different concentration of salt influences the microbial and enzymatic activity, resulting in different flavors. The microorganisms found during Budu production are generally classified as halophilic. The microorganisms play important roles in protein degradation and flavor-aroma development.