Thin juice

Raw juice is heated, treated sequentially with lime (CaO) and carbon dioxide, and filtered. This accomplishes three objectives (/) microbial activity is terminated (2) the thin juice produced is clear and only lightly colored and (J) the juice is chemically stabilized so that subsequent processing steps of evaporation and crystalliza tion do not result in uncontrolled hydrolysis of sucrose, scaling of heating surfaces, or coprecipitation of material other than sucrose. 

Nitrite is usuaUy one indicator of the infection level in the diffuser. Exposure of nitrite to sulfur dioxide, either as a diffusion additive or later to thin juice, results in the production of potassium imidodisulfonate which precipitates when sugar is later crystallized, a cause of turbid or cloudy sugar. 

The product has purities typically in the 90—92% range and can be combined with thin juice, concentrated and crystallized, or concentrated and stored for later use. Crystallizing the desugarization thick juice apart from the normal beet campaign may be desired because the secondary molasses produced after the separation contains the nonsucrose components, which are the most difficult to separate from sucrose and perhaps should be set aside and sold instead of resubmitted to the columns. 

The thin juice discharged from the filter presses after clarification is evaporated to thick juice or evaporator syrup (50-65%... 

The carbonation process can be either continuous or batch processes and is performed in two steps. In the first step, the sludge is separated. In the second step, further addition of carbon dioxide removes the excess lime, which is left in solution. The resulting solution is called thin juice. 

In subsequent sulfitation, a small amount of sulfur dioxide is frequently added to the thin syrup to lighten and stabilize the color during the evaporation process. After sulfitation, the thin juice is again clarified by filtration and is sent to the evaporators. 

Evaporation. The thin juice is heated and pumped fix)m the filter presses to the multiple-effect evaporators. The dissolved solid concentration is raised from an initial concentration of about 15 percent to 50 to 65%. The concentrated juice is now known as thick juice. A decolorizing adsorbent (granular carbon) is added countercurrently in towers to purify and decolorize the thick juice, followed by a tight filtration process. 

Sulfur dioxide is undesirable if the concentration is above a few parts per million. The delicate color of the fruit is impaired and in some cases the metal of the can is corroded. Direct consumption cane sugars produced by the sulfitation process are usually undesirable for canning but the supply is limited to one section of the country. Sulfur dioxide is used in processing beet sugars but not as a bleach as was the practice earlier in the industry. It is now recognized that a few parts per million of sulfur dioxide added before the evaporation of the thin juice act as an inhibitor to the nonenzymatic browning and result in a sugar with less than 1 p.p.m. of sulfur. In the same manner the starch-conversion producers have been able to eliminate the objectionable hydroxymethyl furfural, an undesirable side reaction product in starch conversion. 

Eventually, the cure was found in adjusting the pH when it was discovered that haze developed in syrups produced from thin juices containing sulfates if and when such juices were concentrated to a thick syrup at a pH below 4.5. When a hazy syrup was diluted and reconcentrated above pH 4.8, the haze did not reappear. On the other hand, when a satisfactory syrup was diluted and reconcentrated at pH 4.0 a haze appeared. 

Linsbauer,7 and others found that application of activated carbon to thin juices is very effective for color removal in addition, the removal of nitrogenous substances, calcium, iron, and colloids at this stage is an important advantage. A disadvantage is that a subsequent application of the carbon may be needed when appreciable caramelization occurs during evaporation. 

The purified juice (thin juice) with a dry mass content of some 15% is concentrated in a multi-stage evaporator station to 60-70% (thick juice). 

The thin juice (about 15% solids) discharged from the filter presses after clarification is evaporated to thick juice (50-65% solids) in multiple-effect evaporators. If decolorizing adsorbents are used, they usually are added to the thick juice. Granular carbon and pulverized carbon have been used for this purpose. Thick juice treated with pulverized carbon usually must be double-filtered to remove all of the carbon. 

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