2.6. Enzyme stability during cotton bleaching under ultrasound
In order to evaluate the stability and efficiency of laccase micro-emulsions, desized fabrics were pretreated in the ultrasound bathsonicator (VWR Ultrasonic Cleaner) with fixed frequency 45 kHz and power intensity at 120 W.
One sample was incubated with 2 U/mL of free laccase and other with 2 U/mL of laccase micro-emulsion, in 0.1 M acetate buffer pH 5, at 50◦C during 30 min.
The activity was determined as mentioned in Section 2.4. Cotton samples were further washed with distilled water at 80◦C and dry at room temperature. The pretreated cotton fabrics were bleached afterwards following the recipe: 1 g/L anti-wrinkle, 0.5% wetting agent, 1.5 g/L sequestrant, 4 g/L NaOH, 8 g/L H2O2, 3 g/L equalizer, 1% optical brightener (o.w.f).
The bleaching was carried out at 80◦C for 1 h, assisted by ultrasounds equipment (45 kHz; 120 W).
2.7. Measurement of whiteness index
The whiteness index Berger (W*) of the samples was determined by using a reflectance Data-Colour apparatus at standard illuminant daylight D65.
Supplementary represents the physical appearance of native laccase and the correspondent micro-emulsion where proteins, BSA and laccase, are highly dispersed in the oil as micro-order dispersions. In this process, several factors in the process have been taken into account, namely pressure, temperature, number of pas-sages and flow rate