Stabilization of Allyl Isothiocyanate by β-Cyclodextrin: Thermal Robustness and Potent Antimicrobial Activity

TL;DR

This study shows how β-cyclodextrin can stabilize allyl isothiocyanate, a strong antimicrobial, making it less volatile and more usable in food preservation.

Contribution

The novel use of β-cyclodextrin to stabilize allyl isothiocyanate through co-crystallization, enhancing its thermal robustness and usability.

Findings

AITC@β-CD complexes showed a thermal decomposition temperature of 330 °C, indicating improved thermal stability.

The complexes preserved antimicrobial activity against E. coli and spoiled fruit microbes while masking AITC's pungent odor.

Surface wettability of 89.0° was achieved, making the material compatible with aqueous food systems.

Abstract

Allyl isothiocyanate (AITC) is a potent natural antimicrobial agent; however, its practical application is severely hindered by its extreme volatility and pungent, irritating odor. In this study, AITC inclusion complexes (AITC@β-CD) were successfully fabricated via a co-precipitation strategy using β-cyclodextrin (β-CD) as the host matrix. Physicochemical characterizations, including FTIR, SEM, and XRD, confirmed the successful integration of AITC into the β-CD framework, inducing a crystalline phase transition from a cage-type to a channel-type structure. TGA demonstrated a substantial enhancement in thermal stability, with the maximum decomposition temperature shifting to 330 °C. This indicates that the spatial confinement within the channel-type lattice acts as a robust molecular shield that minimizes premature volatilization. Notably, water contact angle measurements revealed that the complexes attained a modulated surface wettability (89.0°), attributed to the structural rearrangement of surface hydroxyl groups. This modification ensures that the material remains compatible with aqueous food matrices while notably masking the unpleasant sensory attributes of pure AITC. Antibacterial assays against the standard indicator strain Escherichia coli (E. coli) confirmed that the encapsulation process preserved the intrinsic bioactivity of the guest, exhibiting comparable inhibitory zones to free AITC. Furthermore, the complexes maintained high inhibitory efficacy against indigenous microbial populations from spoiled fruits. These findings suggest that β-CD encapsulation effectively stabilizes AITC through guest-induced co-crystallization and enhances its consumer acceptability, providing a versatile and efficient strategy for sustainable food preservation.

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