# A Two-Step Strategy for Aroma Restoration of Strawberry Concentrate Based on ZIF-67@PDMS Composite Membrane

## TL;DR

A new membrane was developed to restore the aroma of strawberry concentrate by efficiently isolating key aromatic compounds.

## Contribution

A ZIF-67@PDMS composite membrane was introduced for enhanced aroma compound separation in strawberry concentrate.

## Key findings

- ZIF-67@PDMS showed improved separation performance for linalool, benzaldehyde, and ethyl acetate compared to pure PDMS.
- The membrane restored both the variety and content of aromatic compounds in strawberry concentrate.
- The aroma profile of the restored concentrate closely matched that of fresh strawberry juice.

## Abstract

An organophilic composite membrane, ZIF-67@PDMS, was fabricated to enhance the isolation of natural aromatic compounds. The as-prepared composite membrane was characterized using SEM, EDS, FTIR, XRD, and contact angle measurement. In comparison to pure PDMS, ZIF-67@PDMS, featuring a loading capacity of 2.5 wt% of PDMS and a membrane thickness of 15 μm, demonstrated markedly improved separation performance for the characteristic aroma compounds of strawberries, namely linalool, benzaldehyde, and ethyl acetate. Under optimal conditions, the permeation fluxes of the three compounds were 628.02 mg∙m−2∙h−1, 294.82 mg∙m−2∙h−1, and 254.14 mg∙m−2∙h−1, along with separation factors of 26.48, 7.94, and 6.32, respectively. ZIF-67@PDMS was then employed to isolate aromatic compounds from freshly squeezed strawberry juice. By backfilling the permeate, both the variety and the content of aromatic compounds in strawberry concentrate were notably restored, and its aroma profile also closely resembled that of fresh strawberry juice.