Branson digital sonifier

Three extracts of the pigments were obtained from 0.5 g of lyophilized microalgae, adding 50 mL of acetone (99% v/v), methanol (99% v/v), and ethanol (96% v/v) as solvent extractants. The extraction was ultrasonic-pulses-assisted (Generator ultrasonic pulses Branson Digital Sonifier Qsonica, LLC. E.U.A). The sample was subjected to 400 w of ultrasonic power for 3 pulses, at 500 mHz and 15 s per pulse at an amplitude of 30%. Then, it was kept in constant agitation for 1 h in darkness. The sample was centrifuged (Beckman model J2-21) for 15 min at 4 °C and 10,000× g. Later, each extract was concentrated in a rotary evaporator (Laborota 4000 Heidolph, Schwabach, Germany) at 45–50 °C. The supernatant was recovered for further analysis. The extracts were re-suspended in three different solvents, acetone (90%), methanol (99%), and ethanol (99%), where the concentrations of the extracts varied according to the biological activities tested [20 (link)].

Tubes with 10 mL of the sample at a concentration of 1 mg/mL were prepared for the application of ultrasonic pulses (Generator ultrasonic pulses Branson Digital Sonifier QSonica, LLC., Brookfield, CT, Middleboro, Massachusetts, USA) according to the combinations provided by the Composite Central Design (Table 1) to optimize the best conditions for obtaining higher antioxidant capacity and total phenols in sorghum lignin. The statistical package JMP version 15.0 (SAS Institute Inc., Cary, North Carolina, USA) was used. During the application of the pulses, 1 min of rest was left after each minute of the pulse applied until the desired time was completed. Subsequently, measurements of antioxidant capacity and quantification of total phenols were performed.