resumo
- The present work focused on the development of a process of sorption-desorption to purify (E)-resveratrol found in winemaking residues, specifically from the crude extract of grape stems. The core element of this process is a photo-molecularly imprinted sorbent (MIS) synthesized by means of the molecular imprinting technique (MIT). This sorbent is a 4-vinylpyridine rich polymer network which binds (E)-resveratrol at stereospecific sites. Comparison of sorption isotherms of the MIS and its counterpart non-imprinted sorbent (NIS) shows the higher capability of the MIS to bind (E)-resveratrol. It is noteworthy that the size of MIS particles was larger than to those of the NIS (as found by scanning electron microscopy analysis) facilitating its use in sorption-desorption processes without reaching a high backpressure. The MIS was then used to purify (E)-resveratrol from grape stems extract in a two-step purification procedure through a simple device. The initial purification step permitted to increase the purity of (E)-resveratrol from 29% to 78% (34% of recovery), whereas a further one took it to 87% (70% of recovery). The purified fractions were obtained in hydroalcoholic medium and contained other bioactive stilbenes such as (E)-Ɛ-viniferin. The results of this research provide a compelling proof of concept for room-temperature photopolymerization, enabling the development of highly efficient imprinted polymers as sorbents for purifying bioactive compounds from agricultural residues. This significant advancement paves the way for its large-scale implementation in a circular bioeconomy approach.