In accordance with one aspect of the invention a testing procedure, a processing procedure and a resulting product are provided whereby sewage sludge is primarily or firstly pre-hydrolyzed in whole or in part by means other than alkali. The alkali is then added to the pre-hydrolyzed product. The pre-hydrolyzed product from step one has a reduced potential for further hydrolysis and is more effectively stabilized in step 2 as a liquid biosolids-containing product or BSP. As a result, in accordance with the invention less of the alkali is used up in the step 2 further alkali-based hydrolysis of the pre-hydrolyzed product. The pH of the BSP product after the step 2 alkali treatment drops less over the period of storage and the BSP product will be better preserved against microbial regrowth.