Improved Control of Sucrose Losses and Clarified Juice Turbidity with Lime Saccharate in Hot Lime Clarification of Sugarcane Juice and other Comparisons with Milk of Lime

A comparative investigation of adding milk of lime (MOL) versus lime saccharate (SACCH) in the hot lime clarification of juice at a U.S. sugarcane factory was undertaken to quantify performance across the 2009 processing season, after a preliminary factory study in 2008. SACCH was prepared by adding hydrated lime to hot clarified juice (CJ) in a greater than 1:7 ratio. The lime treatment was added to flash heated limed juice (FHLJ) to obtain a target CJ pH of 7.3. Samples of FHLJ and CJ were collected six times every 30 min, taking into account the retention time of the clarification tank. Results from the preliminary study suggested that SACCH caused lower turbidity in CJs with better control, as well as higher and better controlled CJ pHs. Across the 2009 season, SACCH factory mud volumes tended to be slightly (no significant difference) higher than for MOL, but no greater than 8.5%. In 2009, CJ turbidities with SACCH were, generally, lower and better controlled than MOL. Lower median particle sizes in CJs with MOL across the season at least partially explain the higher CJ turbidities with MOL than SACCH. For the same amount of hydrated lime added, SACCH produced a higher pH than MOL and this, generally, allowed SACCH to achieve the target CJ pH better than MOL and reduce sucrose losses from acid inversion. No significantly (P < 0.05) extra lime had to be added in the SACCH than MOL treatment, and there were no significant differences between the color of either FHLJ or CJ from SACCH or MOL. Overall, the use of SACCH over MOL improved hot lime clarification especially with respect to the achievement and control of target pH values that saved a considerable amount in sucrose losses and improved turbidity values of clarified juices. Practical Applications This paper is highly practical because in recent years there has been a shift in the U.S.A. and worldwide from the harvesting of burnt to green (unburnt) sugarcane, which has meant that more sugarcane leaves and tops are being processed at factories and have made clarification and sucrose losses worse. The work represented here offers a solution to this by proving that the addition of lime saccharate (SACCH) instead of the traditional milk of lime (MOL), during clarification of sugarcane juice, can improve turbid particle removal and be used as a tool by sugar processors to reduce expensive sucrose losses. This paper reports the performance of MOL and SACCH lime treatments on both the laboratory and factory clarification of sugarcane juices and puts forward explanations for the differences observed.