The smell of ammonia should be produced during fermentation, which is related to the quality of shrimp paste. First-class shrimp paste is tasteless.

First-class products: purplish red in color, sticky in shape, fresh and odorless, delicate in sauce, free of miscellaneous fish and moderate in salinity.

Second-class products: purple in color, soft and thin in sauce, poor in freshness and fragrance, without fishy smell, thick in sauce mixed with small miscellaneous fish, salty or under-fermented.

Third-class products: the color is dark red and not bright, the sauce is thin and rough, there are many miscellaneous fish and sundries, and the taste is salty.