Large-scale production and application of leucine aminopeptidase produced by <Emphasis Type="Italic">Aspergillus oryzae</Emphasis> LL1 for hydrolysis of chicken breast meat

Leucine aminopeptidase (LAP) production by Aspergillus oryzae LL1 (LAP LL1) was scaled up by varying fermenting conditions. The maximal LAP activity for 5, 20, 250, and 2,000 L fermenters were 0.22, 0.16, 0.19, and 0.12 U mL⁻¹, respectively. LAP LL1 production coincides with increasing pH for all scale cases. A pilot plant scale hydrolysis experiment using LAP LL1 was prepared by removing the cells from 1,000 L of A. oryzae LL1 culture and concentrating the supernatant to ∼60 L, with a LAP LL1 activity yield of ∼20% and a specific LAP activity of 0.054 U mg⁻¹, comparable to Flavourzyme. Using a casein substrate, LAP LL1 specific protease activity (50.9 U mg⁻¹) is 43% higher than Flavourzyme (35.6 U mg⁻¹). We believe LAP LL1 has potential use as an industrial enzyme for food processing. Comparing the hydrolysis effects on chopped chicken breast meat (100 g), the degree of hydrolysis (D_H) of LAP LL1 (50.6%) was about twice as effective as Flavourzyme (25.6%). On a pilot-plant scale hydrolysis experiment of chopped chicken breast meat (54 kg), the D_H of LAP LL1 was 45.6%. Adding 30 μmol L⁻¹ zinc increased D_H by 33.3% for LAPs LL1 but zinc did not enhance Flavourzyme hydrolysis. Together, this study provides possibility that LAP LL1 has significant potential for application in the food industry. Shie-Jea Lin and Yi-Hong Chen have contributed equally to this work.