NOVELTY - Method of processing biomass, involves mixing a first batch of biomass and an enzyme to form a first slurry with a first viscosity, adding a second batch of biomass to the first slurry to form a second slurry with a second viscosity, and adding enzyme to the second slurry to form a third slurry with about the first viscosity.    USE - The method is useful for processing biomass (claimed).    ADVANTAGE - The method is simple to perform, and cost-effective.    DETAILED DESCRIPTION - Method of processing biomass, involves (a) mixing a first batch of biomass and an enzyme to form a first slurry with a first viscosity, adding a second batch of biomass to the first slurry to form a second slurry with a second viscosity, and adding enzyme to the second slurry to form a third slurry with about the first viscosity, or (b) providing a reactor with components configured in a flow loop, where the components comprises tank with a mixer, a pump to move material through the flow loop, and a pressure transducer to measure a pressure drop within a pipe that connects the components to form the flow loop, where the flowing material flows within the pipe, loading a first batch of biomass into the tank, monitoring a measured pressure drop within the pipe between a first point along the pipe and a second point along the pipe as the biomass is loaded into the tank, and ceasing the loading when the measured pressure drop within the pipe between the first point along the pipe and the second point along the pipe is at a maximum based on the flow loop's limitations, adding an enzyme to the tank and using the mixing the enzyme with the biomass to form a first slurry, monitoring the measured pressure drop within the pipe between the first point along the pipe and the second point along the pipe as the slurry is formed, when the measured pressure drop within the pipe between the first point along the pipe and the second point along the pipe reaches a quasi steady state after a decrease in the measured pressure drop within the pipe between the first point along the pipe and the second point along the pipe, adding an additional batch of biomass into the tank until the measured pressure drop within the pipe between the first point along the pipe and the second point along the pipe is at the maximum based on the flow loop's limitations, adding additional enzyme to the tank and mixing the enzyme with the biomass to form a second slurry, where pH of each slurry is maintained at an approximately constant value by adding a buffer or by adding at least one of an acid and a base to each slurry, and repeating steps until a desired quantity of biomass is processed.