Rosenthal, I., Department of Food Science, Agricultural Research Organization, Volcani Center, P.O.Box 6, Bet Dagan 50250, Israel Rosen, B., Department of Food Science, Agricultural Research Organization, Volcani Center, P.O.Box 6, Bet Dagan 50250, Israel Bernstein, S., Department of Food Science, Agricultural Research Organization, Volcani Center, P.O.Box 6, Bet Dagan 50250, Israel
Ferulic and p-coumaric acids, natural phenol derivatives which are constituents of cell-wall of plant material, were found to inhibit the multiplication of contaminating yeast cells isolated from fresh white cheese. The inhibition was demonstrated in growth medium and, for ferulic acid, also in white soft cheese. On the other hand, the corresponding rumen metabolites of these compounds, hydrogenated phenol-containing acids, were comparatively inactive in the inhibition test. Noteworthy is also the efficient antiyeast activity of ellagic acid, a natural phenol found in bark. While the effects of phenolics on ruminal digestion of forage and on ruminai microbial activity have been investigated extensively, to the postabsorptive effects of phenolics or their metabolites has been given little attention. Incidental high concentrations of phenols in raw milk might, hypothetically, have technological and safety implications. In these respect, the effect of several substituted phenol derivatives on a standard diffusion test for the detection of antibiotic and sulpha residues in raw milk (Delvotest SP), and on phosphatase test of pasteurized milk, was determined. Under the present experimental conditions, no interference of these additives with the expected results of these tests was observed.
Phenols in milk. Evaluation of ferulic acid and other phenols as antifungal agents
52
Rosenthal, I., Department of Food Science, Agricultural Research Organization, Volcani Center, P.O.Box 6, Bet Dagan 50250, Israel Rosen, B., Department of Food Science, Agricultural Research Organization, Volcani Center, P.O.Box 6, Bet Dagan 50250, Israel Bernstein, S., Department of Food Science, Agricultural Research Organization, Volcani Center, P.O.Box 6, Bet Dagan 50250, Israel
Phenols in milk. Evaluation of ferulic acid and other phenols as antifungal agents
Ferulic and p-coumaric acids, natural phenol derivatives which are constituents of cell-wall of plant material, were found to inhibit the multiplication of contaminating yeast cells isolated from fresh white cheese. The inhibition was demonstrated in growth medium and, for ferulic acid, also in white soft cheese. On the other hand, the corresponding rumen metabolites of these compounds, hydrogenated phenol-containing acids, were comparatively inactive in the inhibition test. Noteworthy is also the efficient antiyeast activity of ellagic acid, a natural phenol found in bark. While the effects of phenolics on ruminal digestion of forage and on ruminai microbial activity have been investigated extensively, to the postabsorptive effects of phenolics or their metabolites has been given little attention. Incidental high concentrations of phenols in raw milk might, hypothetically, have technological and safety implications. In these respect, the effect of several substituted phenol derivatives on a standard diffusion test for the detection of antibiotic and sulpha residues in raw milk (Delvotest SP), and on phosphatase test of pasteurized milk, was determined. Under the present experimental conditions, no interference of these additives with the expected results of these tests was observed.