Control Efficacy of Salicylic Acid Microcapsules against Postharvest Blue Mold in Apple Fruit

Salicylic acid (SA) is a natural inducer of disease resistance in fruit, but its application in the food industry is limited due to low water solubility. Here, SA was encapsulated in beta-cyclodextrin (beta-CD) via the host-guest inclusion complexation method, and the efficacy of SA microcapsules (SAM) against blue mold caused by Penicillium expansum in postharvest apple fruit was elucidated. It was observed that SAM was the most effective in inhibiting the mycelial growth of P. expansum in vitro. SAM was also superior to SA for control of blue mold under in vivo conditions. Enzyme activity analysis revealed that both SA and SAM enhanced the activities of superoxide dismutase (SOD) and phenylalanine ammonia lyase (PAL) in apple fruit, whereas SAM led to higher SOD activities than SA. Total phenolic contents in the SAM group were higher than those in the SA group at the early stage of storage. SAM also improved fruit quality by retarding firmness loss and maintaining higher total soluble solids (TSS) contents. These findings indicate that microcapsules can serve as a promising formulation to load SA for increasing P. expansum inhibition activity and improving quality attributes in apple fruit.

Automated summary

In this study, salicylic acid (SA) was encapsulated in beta-cyclodextrin (beta-CD) to form microcapsules, which showed effective inhibition against blue mold caused by Penicillium expansum in apple fruit. The microcapsules not only enhanced the antifungal activity of salicylic acid, but also improved the quality attributes of the fruit.