I Have Been Dressing My Sisters Dehiscence Wound. It Is

I have been dressing my sisters dehiscence wound. It is a lower back surgery. It opened through all layers. Very deep. I have been packing it with gauze soaked with Dakin. When I removed packing it looked like white fatty tissue built up. Almost like gauze. Had emergency room look at it and do your said it is healing. What is that whit stuff?