Six strains of Aspergillus flavo furcatis were screened to investigate milk-clotting enzyme production by fermentation in natural liquid medium. The growth media comprised extracts of cupuaçu exocarp+rice bran [10% or 20% (v/v) CE+RB] and açai waste+rice bran [10% or 20% (v/v) AW+RB] with or without supplementation of 0.1% (w/v) yeast extract and 0.5% (w/v) gelatin. Significant values of milk-clotting activity were determined by A. flavo furcatis DPUA 1461 and DPUA 1608, in the standard and natural media, respectively. According to criteria of clot and whey formations, 8.3% of the samples tested were classified as strong coagulation, 41.70% showed weak coagulation and in 50% was not observed milk coagulation. The enzyme optimal action of DPUA 1608, the selected strain, was at 40 °C and pH 7.0. Milk-clotting proteases were inhibited by pepstatin (94.72%) and moderately inhibited by the others metal ions tested.Summary
Strains of Aspergillus flavo furcatis (1) were fermentated in liquid media composed of cupuaçu exocarp and açai waste, both were mixtured with rice bran (2). The crude extracts (3) obtained were used for determination of milk-clotting activity (4).