A study was conducted by the Eastern Regional Research Center, Agricultural Research Service, US Department of Agriculture. They state that "Hispanic-style cheeses are one of the fastest growing varieties in the United States, making up approximately 2% of the total cheese production in this country. Queso Fresco is one of most popular Hispanic-style cheeses."
Proteins from 18 different "queso fresco" cheeses were analyzed for potential antihypertensive activity. 6 were Mexican-style "queso fresco," made from raw milk, 12 were made from pasteurized milk and did not utilize starter cultures.
Researchers were looking for the proteins' ability to inhibit the angiotensin-converting enzyme (ACE) - an enzyme that participates in vasoconstriction (narrowing of blood vessels).
Cheeses were aged, and proteins were extracted periodically.
All cheeses produced ACE-inhibiting proteins.
The 6 Mexican style "queso fresco" cheeses stood out, however - the proteins were found only a few days after being aged. The model cheeses, made from pasteurized milk, produced these same results "after 8 weeks of aging when they were no longer consumable."
[PubMed]: Short communication: Assessing antihypertensive activity in native and model Queso Fresco cheeses