Application of cinnamon essential oil microcapsules in anti-fungal preservation of Spatholobi caulis

Spatholobi Caulis (SC), a traditional Chinese medicinal material, is susceptible to fungal contamination during storage. This study aimed to compare the antifungal efficacy of plant-derived essential oils against the dominant fungal contaminants in SC and evaluate their potential applications in storage preservation. The dominant fungal strains contaminating SC during mildew development were isolated and identified through morphological and molecular biological analyses. An essential oil exhibiting significant antifungal activity against the dominant strains was screened via the filter paper diffusion assay and the poisoned medium technique. The microencapsulation protocol for essential oils was optimized using a Lorthogonal array design. The preservative efficacy of microencapsulated essential oils on SC was evaluated through accelerated aging tests. Four dominant fungal species were identified in mildewed SC: Penicillium implicatum (JXT-1), Talaromyces rugulosus (JXT-2), Aspergillus sydowii (JXT-3), and Aspergillus niger (JXT-4). Cinnamomum cassia essential oil demonstrated superior antifungal activity against these isolates, showing significantly greater efficacy than other tested essential oils. The optimized microencapsulation parameters were determined as: wall-to-core ratio (4:1), processing temperature (60 ± 0.5 °C), and duration (2.0 h), yielding an encapsulation efficiency of 68.03%. Accelerated stability testing revealed that microencapsulation significantly reduced both active component degradation and aflatoxin A accumulation compared to non-encapsulated controls. These results demonstrate that Cinnamomum cassia essential oil microcapsules effectively preserve SC quality by maintaining bioactive compound stability.