Viability And B-Galactosidase Activity Of Dairy Propionibacteria Subjected To Digestion By Artificial Gastric And Intestinal Fluids

G. ZÁRATE; A. PEREZ CHAIA , S. GONZÁLEZ AND G. OLIVER

JOURNAL OF FOOD PROTECTION

INT ASSOC FOOD PROTECTION

Lugar: Des Moines, Iowa, U.S:A; Año: 2000 vol. 63 p. 1214 - 1221

0362-028X

Viability And b-Galactosidase Activity Of Dairy Propionibacteria Subjected To Digestion By Artificial Gastric And Intestinal Fluids Gabriela ZÁRATE1, Adriana PÉREZ CHAIA1,2 *; Silvia GONZÁLEZ1,2, and Guillermo OLIVER1 An important criterion to consider in the selection of strains for dietary adjuncts is the ability of the microorganisms to survive the severe conditions of acidity and bile concentrations usually found in the gastrointestinal tract. In the present work we report the effects of digestions by artificial gastric and intestinal fluids on b-galactosidase activity and survival of four strains of dairy propionibacteria previously selected by their bile tolerance and b-gal activity. The strains were exposed to artificial gastric juice at pH values between 2 and 7 and then subjected to artificial intestinal digestion. Both viability and b-galactosidase activity were seriously affected at pH 2. Skim milk and Emmental cheese juice exerted a protective effect on the parameters tested. The trypsin present in the intestinal fluid inactivated the enzyme b-galactosidase in strains of P.freudenreichii but not in P.acidipropionici.  Moreover, the presence of bile salts enhanced the b-galactosidase activity of these strains by permeabilization of the cells during the first hour of exposure. The intestinal transit rate confirmed the permanence of the bacteria in the intestine for long enough to be permeabilized. These results suggest that P.acidipropionici would be a good source of b-galactosidase activity in the intestine. We also propose a practical and effective in vitro method as a tool of screening and selection of potential probiotic bacteria.