RESUMO
This study aimed to optimize free fatty acid production by enzymatic hydrolysis of cottonseed, olive and palm kernel oils in stirred-tank reactors using a lipase from Geotrichum candidum (GCL-I). The effect of pH, temperature and substrate concentration on the hydrolytic activity of GCL-I using these vegetable oils was investigated. Thermal stability tests and thermodynamic studies were also performed. A complete hydrolysis of cottonseed oil was obtained after 120 min of reaction, while for olive and palm kernel maximum hydrolysis percentage was 96.4% and 60.1%, respectively. GCL-I exhibited the highest activity in the hydrolysis of vegetable oils that are rich in unsaturated-fatty acids (cottonseed and olive oils). Under optimal conditions (46.8% m/m of oil, 6.6 U/g of the reaction mixture at 40 °C), complete cottonseed oil hydrolysis was observed at 60 min of reaction performed in an emulsifier-free system with no buffer.
