Harmful nitrogen represents the soluble nitrogen of sugar beet which c
annot be eliminated during traditional juice purification (e.g. total
nitrogen in thick juice). For this reason harmful nitrogen is an impor
tant criterion of beet quality. Using the recently developed pyro-chem
iluminescence method harmful nitrogen can be determined in beet extrac
ts clarified with aluminium sulphate as aluminum sulphate soluble nitr
ogen (AlN). In a first overview the harmful nitrogen content of sugar
beet from a variety- and nitrogen fertilizer trial is presented. Harmf
ul nitrogen, together with other beet constituents, is subsequently us
ed for quality assessment after the presently applied quality criteria
. In contrast to the usual amino-N analyses harmful nitrogen determina
tions by means of aluminum sulphate soluble nitrogen (AlN) will take i
nto consideration this most important N-fraction of sugar beet in qual
ity assessment and breeding for low nitrogen sugar beet varieties with
sufficient alkalinity reserves.