PHENOLS IN MILK - EVALUATION OF FERULIC ACID AND OTHER PHENOLS AS ANTIFUNGAL AGENTS

Ferulic and p-coumaric acids, natural phenol derivatives which are con stituents of cell-wall of plant material, were found to inhibit the mu ltiplication of contaminating yeast cells isolated from fresh white ch eese. The inhibition was demonstrated in growth medium and, for feruli c acid, also in white soft cheese. On the other hand, the correspondin g 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 p henol found in bark. While the effects of phenolics on ruminal digesti on of forage and on ruminal microbial activity have been investigated extensively, to the postabsorptive effects of phenolics or their metab olites 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 substitut ed phenol derivatives on a standard diffusion test for the detection o f antibiotic and sulpha residues in raw milk (Delvotest SP), and on ph osphatase test of pasteurized milk, was determined. Under the present experimental conditions, no interference of these additives with the e xpected results of these tests was observed.