A new method was developed using sulphur dioxide in the purification : a combination of sulfkation of diffusion juice before D-V prdLiming with milk of lime.
We followed the influence of sulphurous acid on the filtration- and sedimentation ability of clarified juice and thickened mud1 and on the colour of thick juice. The amount of S02 added was expressed by the pH decrease of the diffusion juice.
A small addition of S02 into the diffusion juice (pH 5.5 – 6.0), causes the technological properties of the juices to change significantly. Especially the filtration and sedimentation of clarified and of the muddy juice improve after a certain addition of S02, which may be qualified as optimal. A further addition of S02 into the juice reduces the above mentioned properties to the original value. Similarly, the lowest colour of thick juice corresponds with the above mentioned optimal value for filtration and sedimentation. The amount of precipitated colloidal non-sugars during purification process is maximal in the juice sulfitated to the optimum.
The content of lime salts in thin and thick juice increases in straight proportion to the increase of the added S02. Extremely high limesaits were however obtained only with a high content of S02. Such a marked decrease of alkality cannot be allowed in factory conditions. The unfavourable influence of sulfitation on the limesait content of the juice is compensated by an improved filtration and by low colour of juices. Further detailed research is in progress.
Proceedings: CITS 1971
pdf download: CITS1971-23-34.pdf