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Bitterness such as Naringin in Grapefruits and Limonin in all Citrus fruits have a strong influence on consumers’ choices for their favorite juices. There have been many methods from ultrafiltration to biocatalysis used to lower such bitter compounds and make the juices more desirable by the consumer. One major tool for such debittering operation is the use of synthetic adsorbents which will be discussed in this paper. Ion exchange resins and adsorbents have been used for over a century in various food applications to concentrate flavors, decolorize juices, and enhance the quality of the final product. These types of resins are being synthesized to specific parameters to distinguish them from other tools. Mitsubishi Chemical’s work on optimizing their synthetic adsorbents for high bitterness removal from citrus juice was investigated. Parameters such as the base matrix structure, pore size and distribution, as well as the effect of surface area were studied. As the FDA has strict definitions about the appropriate resin chemistry that can be used in a food application (21 CFR 173.65), progress in new resin chemistry was limited by such regulations. This paper discusses the use of the original Sepabeads SP70 which was introduced into the market about 20 years ago, to the high capacity resin, Sepabeads SP700, which was introduced 10 years ago, and finally, to the Sepabeads SP710, which is the current optimized version of 20 years of research work. Mitsubishi Chemical’s resins were compared to other resins in the industry for the removal of naringin, limonin, and 8-hydroxyfuranocoumarin (furanocoumarins are compounds that affects the proper absorption of certain medications). Proper regeneration and rejuvenation of these resins were outlined. Paper published with permission.

Chromates are widely used for their anticorrosive properties. Unfortunately, they are highly hazardous with environmental agencies regulating their levels to below 10 ppb in drinking water. As anion exchange resins are typically used for removal, predictive dynamic models are necessary to make quick decisions rather than relying on experimental data that could take several days to implement. With various dynamic models currently applied to simulate the ion exchange process, the Thomas model was picked for its simplicity and better accuracy when compared to other models. The Thomas model contains two parameters, the constant (KT) and the maximum resin capacity (qm), which are empirically calculated. Unfortunately, the model demonstrated large parameter fluctuations with no correlation to varying contact times or inlet chromate concentrations. Therefore, fixing both parameters will lead to failed model predictive behavior. By fixing the value of qm and proposing a linear relationship of KT with resin contact time and inlet chromate concentration, the accuracy of the model was improved five-fold, demonstrating its potential for better process controls.

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