Fruit sugar syrup decolorization and deminaralisation

Fruit syrup are often used as substitute of cane or beet sugar for various fruit soft drink or wine improvement (using grape juice). The removal of the color and HMF compounds can be performed on activated carbon and more and more on a macroporous adsorbent resin, more easy to handle and to regenerate on-site than traditional carbon. The demineralization is done on ion exchange resins, mainly macroporous type for their large pores and better mechanical resistance.

The layout will depend on the syrup and targets, using Strong Acid Cation in H+ form to remove K+, Ca2+, Mg2+ and nitrogenous compounds, Weak Base and Strong Base Anion resins (WBA and SBA) to remove the free acidity.

Apple and pear syrup have a high content of “natural” sucrose, glucose and fructose, but need to be demineralized and color free before use in carbonated soft drinks.

The demineralization and decolorization of apple juice is generally performed on SAC->WBA-Adsorbent, but in case of high free acidity, we can also propose Adsorbent->WBA->SAC->WBA . Patuline is a mycotoxine present in apple juices and its removal is operated on activated carbon or on a specific styrenic adsorbents.

On pear juice, the traditional layout is SAC->WBA->Adsorbent or Activated carbon

The production of canning syrups from pineapple mill juice is using a merry-go-round layout : (SAC->WBA)->(SAC->WBA) to remove the citric acid and nitrogenous compounds.

The end of cycle is determined when the first pair is exhausted. Regeneration is using NaCl from SAC to WBA where Ca²⁺ is eluted from the SAC and remove the citric acid from the WBA, before recovery by precipitation of calcium citrate.

On white grape juice, the production of canning syrup is done on different possible layout, mainly SAC->WBA->SBA->SAC with sometime an adsorbent in front (before the first SAC)