Fig 1. SDS-PAGE for protein size determination in the hydrolyzed after alkali, thermal-alkali and Ultrasonic-alkaly hydrolysis

The size of the recovered peptides, in kDa, from all the liquid fractions obtained after the applied treatments was characterized by using a sodium dodecyl sulphate polyacrylamide electrophoresis (SDS-PAGE) using a Bio-Rad Mini-PROTEAN SystemTM with Mini-PROTEAN 10-20% Tris-Glycine Precast Gels (Bio-Rad Laboratories, USA) [24]. Molecular protein bands were analyzed according to the intensity of the bands and their distances according to the protocol described by the manufacturer. Proteins of known molecular weight (250 - 5 kDa) (PageRuler Plus Prestained, Thermo Scientific) were used to calibrate the gel system.