Evaluation of the adsorption behavior of polyacetylenes onto a food-grade resin for the debittering of carrot juice

Abstract

In the present study, a procedure for the adsorptive removal of bitter principles, such as the polyacetylenes falcarinol, falcarindiol, and falcarindiol-3-acetate, from carrot juice using a food-grade macroreticular, non-ionic adsorption resin was investigated. To characterize the adsorption behavior of the target compounds, the influence of the independent factors resin amount, stirring rate, pH value, and temperature was studied first in batch-scale experiments. Based on mathematical models obtained from the analysis of the D-optimal design applied, optimal adsorption conditions of each polyacetylene were deduced. Taking together these findings, the adsorption behavior of polyacetylenes was investigated in column experiments. To enhance the binding rates by increasing contact times, the carrot juice was two- and threefold re-applied to the column at 30 °C. As expected, relative amounts of polyacetylenes bound by the adsorbent increased with prolonged contact time of carrot juice and resin material. After a contact time of 64 min, nearly 90% of total polyacetylenes were sorbed onto the resin surface. Therefore, the described adsorption technique may present a valuable tool for the removal of polyacetylenes from carrot juice and thus for debittering. On the other hand, adsorption may be utilized for the recovery and enrichment of these plant secondary metabolites and their use as a functional ingredient in pharmaceutical products and dietary supplements, respectively.