A fiber washing system comprising a plurality of screen units (S1...S4) being fluidly connected in a counter current washing configuration; each screen unit is configured for separating a stream of corn kernel mass and liquid into two fractions: - a first fraction (s) and a second fraction (f), said second fraction (f) containing a higher amount measured in wt% fiber than the first fraction (s); wherein the system is configured for - inletting corn kernel mass and liquid to the most upstream screen unit (S1) - outletting the first fraction (s1) from the most upstream screen unit (S1) as a product stream containing starch, - inletting process water, preferably arranged for inletting process water to a most downstream screen unit (S4), - outletting the second fraction (f4) from most downstream screen unit (S4) as a washed corn kernel mass containing a lower amount of starch and gluten than the original corn kernel mass. - introducing hydrolytic enzymes into the system; characterized in that the system is configured for introducing said hydrolytic enzymes into said first fraction (s), and/or into said second fraction (f), and/or into a mixed first and second fraction and/or into the stream of process water supplied to the system; and wherein the system comprise a most upstream screen unit (S1... S4), a most downstream screen unit and one or more intermediate screen units fluidic arranged in between the most upstream and most downstream screen units (S1, S4); and wherein said fluidly connected counter current washing configuration, comprising the plurality of screen units (S1... S4), is arranged in a manner so: a second fraction (f1) produced by an upstream screen unit (S1) is mixed with a first fraction (s3) produced by a downstream screen unit (S3), and said mixed fractions being separated by a screen unit (S2), being intermediate between said upstream and said downstream screen units (S1, S3), into a first fraction (s2) and a second fraction (f2); a space (V) arranged in the system and being fluidly connected to receive one of said first fraction (s), one of said second fraction (f), or a mixed first and second fraction (s,f), preferably only a second fraction (f), and configured to provide an incubation time for one or both fractions received in the space; and outletting the thereby incubated one or both fractions to a downstream screen unit (S4), and wherein said space (V) is configured to provide an incubation time of at least 5 minutes, preferably at least 15 minutes, such as at least 30 minutes, preferably at least 45 minutes, such as at least 1 hours, and preferably less than 12 hours. - a first fraction (s) and a second fraction (f), said second fraction (f) containing a higher amount measured in wt% fiber than the first fraction (s); - inletting corn kernel mass and liquid to the most upstream screen unit (S1) - outletting the first fraction (s1) from the most upstream screen unit (S1) as a product stream containing starch, - inletting process water, preferably arranged for inletting process water to a most downstream screen unit (S4), - outletting the second fraction (f4) from most downstream screen unit (S4) as a washed corn kernel mass containing a lower amount of starch and gluten than the original corn kernel mass. - introducing hydrolytic enzymes into the system; <EOS>