MODIFIED SINGLE SULFITATION PROCESS FOR PRODUCING BETTER QUALITY PLANTATION WHITE SUGAR

Abstract THE PRESENCE of sulfur in sugar, apart from making it potentially harmful for human consumption, causes the sugar to deteriorate at a faster rate during storage. These issues and the steep rise in sulfur prices, albeit temporary, have brought to the fore the need to reduce the sulfur dosage used in the production of plantation white sugar (PWS). The process generally used in the production of PWS (in addition to juice sulfitation) is syrup sulfitation, which reduces sugar colour by a further 6-15%. However, this reduction in sugar colour is short-lived and it also reduces the pH of the syrup, with the result that subsequent manufacturing processes are carried out under acidic conditions. Because of this, there could be significant sugar losses from sucrose inversion. The use of suitable biocides for cane and mill sanitation has been shown to reduce the acidity of the mixed juice, as also the quantum of the high molecular weight polymeric compounds in the sugar and the molasses. In view of these observations, a new process (the VMK process) was developed to produce PWS without resorting to syrup sulfitation, namely, a single sulfitation process using a polymer together with appropriate biocides that reduce impurities and colour by about 12-15%. This process was tried in a full season of about 100 days in a 2500 tcd factory where 25 000 t of sugar was produced with colour below 80 IU. Further improvement in sugar quality was also achieved with the help of an on-line colour monitoring unit, WG Colormet 1.0, as well as through tight control on chemical consumption, especially that of lime and sulfur. The quality of the sugar, which was consistently achieved, showed colour to be <55 IU, conductivity ash <0.015%, calcium <30 ppm, pol >99.85, and dextran and sulfur below detectable limits. The colour transfer index was found to be 130:1 from clear juice to final sugar, as against the reported index of 100:1 from A massecuite to sugar. Based on these findings, a patent has been filed for the VMK process for the production of good quality PWS