RESUMEN
Sixteen batches of Prato cheese, run in duplicate, were processed with grade C, 3.2% fat, pasteurized milk. One run was processed in the traditional way and in the second run the milk was previously enriched with concentrated whey proteins (CWP) recorvered by ultrafiltration from run one. The mean total mesophilic counrs increased about ten fold during concentration of Prato cheese whey and the mean counts were 9.2% x 10**3, 6.4 x 10**1 and < 1 for mesophilic, yeast/fungi and coliforms respectively in CWP after heat treatment at 80 §C for 3 min. Although the total final counts for mesophilic and coliforms did not change significantly in both cheeses, there was a significant increase in the number of yeast/fungi for Prato cheese enriched withm CWP