Scanning electron microscopy(SEM)
SEM micrographs of previously untreated grape pomace samples, after heat treatment at 35 ◦C for 60 min,and after ultrasound
treatment during 60 min at 35 ◦C, were obtained with a Hitachi
S-3400N (Japan) scanning electron microscope at an accelerating
voltage of 10 kV.Samples were directly observed,without further
treatment, under a pressure of 40 Pa.