AbstractIn order to increase the availability of the cell bound protein inScenedesmusalgae, mechanical, enzymatic, and chemical methods of degrading the cell wall structure were investigated.Mechanical treatment involved the use of a ball‐mill. The algae suspension together with glass beads was milled in a water‐cooled chamber equipped with rotating disks. The enzyme tested was a cellulolytic enzyme (Meicelase) and the chemical employed was hydrogen peroxide.In the ball‐mill experiments a complete disintegration was achieved ina disintegrator, working with batches. Trails wwere also performed with a continuous disintegrator and the depedence of disintegration on bead size and flow rate was studied. The disintegration determined by microscropic cell count was compared to the increase of the pepsin digestibility.The meicelase treatment caused a slight increase of the pepsin digestibility, as measured after 3 hr pepsin incubation. No increase of the pepsin disgestibility could be detected with hydrogen peroxide treatment.After the ball‐mill disintegration 95% of contaminating bacteria were killed and yields of extractable proteins were higher. The capacity of availble continuous ball‐mills is such that they could be used on a pilot‐plant scale and the energy cost of disintegration would be of the same magnitude as that of