The improvement of milk by cultivation with ciliates.

G. VALCARCE; L. MUÑOZ; A. NUSBLAT; C. NUDEL; J. FLORIN-CHRISTENSEN

JOURNAL OF DAIRY SCIENCE

American Dairy Science Association

Lugar: United States; Año: 2001 vol. 84 p. 2136 - 2143

0022-0302

The exceptional nutritional values of milk have long been recognized. However, important drawbacks of milk and dairy products are their relatively high cholesterol contents and their low proportion of polyunsaturated fatty acids. Hypersensitivity to milk proteins can also draw the public away from fluid milk consumption. The nonpathogenic ciliate Tetrahymena thermophila has a unique set of enzymes that converts cholesterol into provitamin D3 and related compounds. It also contains D 12 fatty acid desaturases and releases various hydrolases, including proteases, lipases, and phospholipases. We investigated the potential use of these peculiar traits to improve milk by short-term incubation with live ciliate suspensions. We found that cholesterol can be reduced to 50% of its initial content in whole milk by a 12-h period of incubation with T. thermophila cells, mostly by conversion to D7-desaturated cholesterol derivatives, including provitamin D3. In addition, a considerable increase in -linolenate (18:3, n-6) takes place. The protein profile is markedly changed by proteolysis, with a striking reduction of casein and enhancement in total amino acid content. Despite these changes, no marked alterations in flavor or odor were observed at the end of 12 h of incubation. Thus, Tetrahymena appeared ideally suited to correct for milk drawbacks, making this important source of nutrients more acceptable to the health-conscious public.