Algal extracts for postharvest phytopathogen control in agri-food industry

Postharvest losses in fruits due to microbial decay and physiological deterioration are a major challenge to the agricultural sector. Although chemical disinfectants are commonly used to mitigate this risk, many of these substances are toxic, corrosive, and harmful to the environment. As a result, there is growing interest in natural, safe, and eco-friendly alternatives. This study evaluated the antifungal and antibacterial activity of 18 macroalgal extracts against postharvest pathogens, including Botrytis cinerea, Aspergillus spp., Penicillium spp., and Pseudomonas syringae. Ulva sp. and Mazzaella sp. extracts exhibited the strongest activity, inhibiting conidial germination, mycelial development, and both planktonic and biofilm bacterial growth. Cytotoxicity assays in Neuro-2a cells confirmed their safety at active concentrations, while ecotoxicological analyses indicated acceptable environmental safety (LC₅₀ of 3.54 ± 0.57 mg⸱mL⁻¹ for Ulva sp. and 14.4 ± 0.28 mg⸱mL⁻¹ for Mazzaella sp., with a NOEC of 0.312 mg⸱mL⁻¹ for both). Both extracts significantly reduced postharvest rot in blueberries, grapes, and cherries, with Mazzaella sp. showing the most consistent efficacy, particularly against Aspergillus spp. and Penicillium spp. These findings highlight the potential of macroalgal extracts as sustainable alternatives to synthetic disinfectants, enhancing food biosecurity and reducing postharvest losses in the agri-food industry.