Patent ID: 8764942

Claim:
A method to preserve starch present in pulp comprising: in a papermaking process having a head box or roundformer and process water containing pulp and wherein said process water is susceptible to production of amylase and amylolytic bacteria, measuring chemical oxygen demand of said process water and measuring calcium ion levels of said process water to obtain measured calcium ion levels, and treating said process water containing said pulp with chloramine comprising monochloramine such that said process water has a residual chloramine amount of from 0.3 ppm to 15 ppm at the head box or roundformer, and further treating said process water containing said pulp with at least one oxidant, wherein pre-existing starch is present in said pulp, before said and after said treating, in an amount of at least 0.001 wt % based on weight of dried pulp fiber, and wherein said chloramine is added based on at least said measured calcium ion levels in said process water, and wherein said treating comprises continuously treating for at least 1 month and maintaining said residual chloramine amount, and wherein production of amylase is controlled or prevented such that amylolytic bacteria are present in an amount of less than about 1.0×10 15 cfu/g dry pulp in said process water.