SO2 give rise to different cellulose qualities and thus also
different sulphite-spent liquors (LS), which then give different
yields of vanillin in the oxidation process. The LS
types, LS750 and LS850, obtained from cellulose processes
using a high digestion temperature give a yield of vanillin
in the range 4.0-4.2% when using LS750 and 4.2-4.5%
when using LS850. Lignosulfonates type LS1200 obtained from
processes with a lower digestion temperature give significantly
higher yields of vanillin (5.8-6.2%).