Methods to preserve starch present in pulp are disclosed and also methods to control calcium precipitation and/or scaling in digesters or BOD systems. The methods can be performed as part of a papermaking process. Process water containing pulp can be treated with a chloramine. Process water containing pulp with native starch can receive a double treatment with at least one biocide, such as chloramine, and at least one oxidant, such as sodium hypochlorite. The treatment can be performed in any suitable manner. The treatment can be performed at one or more stages or locations in a papermaking system. A target residual chloramine value or range can be achieved by the treatment. Packaging sheets/boards and other paper products manufactured using the methods provided exhibit superior strength and other desirable characteristics.
