Production of casein hydrolysates by extracellular acid proteinases of immobilized Humicola lutea cells

Casein hydrolysis was studied during the cultivation of immobilized Humicola lutea cells producing acid proteinases. By monitoring the cultivation with time, various casein hydrolysates could be obtained, from partially modified proteins (yield 80%) with improved emulsion properties to peptones (yield > 50%) with a degree of hydrolysis >40%. The casein from the fermentation medium appeared to be simultaneously a nitrogen source, an inducer of proteinase biosynthesis, and a substrate for the production of casein hydrolysates. Casein (4%) and glucose (2%) ensured optimal cultivation conditions. The fungal cells, immobilized in calcium alginate beads, required a short cultivation time and demonstrated comparable hydrolysis of casein during five to seven reuses in batch mode.Correspondence to: B. Tchorbanov