ABSTRACT
This research investigated the technical feasibility of metal-organic frameworks (MOFs) as novel delivery systems for encapsulation and controlled release of volatile allyl isothiocyanate (AITC) molecules. We hypothesized that water vapor molecules could act as an external stimulus to trigger the release of AITC molecules encapsulated in MOFs. To test this hypothesis, three MOFs-HKUST-1, MOF-74(Zn), and RPM6-Zn-were selected based on their structural properties and AITC molecular characteristics. Results from adsorption-desorption and GC headspace analyses showed that these MOFs could encapsulate and retain AITC molecules within their pores under low (30-35%) relative humidity (RH) conditions. In contrast, the release of AITC molecules from all these MOFs was triggered under high RH (95-100%) conditions. These findings along with results from SEM, TEM, and XRPD studies support our hypothesis that water vapors could trigger the AITC release from these MOFs, indicating that development of the AITC-MOFs delivering system is technically feasible.
Subject(s)
Delayed-Action Preparations/chemistry , Isothiocyanates/chemistry , Organometallic Compounds/chemistry , AdsorptionABSTRACT
In this work we demonstrate that allyl isothiocyanate (AITC), a common food flavoring agent and food preservative, can be effectively captured by and released in a controlled manner from a microporous metal-organic framework (MOF). The extent of AITC-MOF interactions is quantitatively measured by orbital overlap population calculations. Controlled release experiments show that loaded AITC can be released by applying higher relative humidity. Further analysis reveals that the underlying mechanism of the controlled release is associated with the transformation of the MOF from a porous to a nonporous structure at high humidity. This study represents the first example of making use of MOF porosity in food preservation.