Adsorption-desorption of trehalose analogues from a bioconversion mixture using activated carbon

Trehalose (α-d-glucopyranosyl α-d-glucopyranoside) is widely used in the food industry, because of its protective effect against freezing and dehydration. Analogues of trehalose have the additional benefit that they are not digested and thus do not contribute to our caloric intake. Such trehalose analogues can be produced with the enzyme trehalose phosphorylase, when it is applied in the reverse, synthetic mode. A cost-effective purification procedure is, however, still lacking. Therefore, the adsorption of trehalose on activated carbon has been studied and compared with that of galactitol, i.e. the major contaminant in the process. The adsorption capacity of trehalose was found to be significantly higher than that of galactitol, which suggested that trehalose analogs could be removed from the bioconversion mixture. Selective desorption with aqueous ethanol allowed to recover the product with a purity of more than 97%. Preceding the adsorption/desorption procedure by an ion-exchange step increased the yield from 24% to 31%, but also increased the price. Therefore, the direct use of activated carbon is proposed as new strategy for the purification of enzymatically produced trehalose analogues. © 2012 Elsevier B.V. All rights reserved.