Phlorotannins extracted from Sargassum ilicifolium as a way to control spoilage molds and extend the shelf life of Agaricus bisporus mushrooms

Phlorotannins (PTs) are compounds with notable bioactive characteristics obtained from brown algae. In the present study, PTs from the Sargassum ilicifolium seaweed were extracted, characterized, and evaluated for their anti-polyphenol oxidase (PPO) enzyme activity and in vitro antifungal activity against spoilage molds (Aspergillus flavus and Penicillium expansum) of button mushrooms. Then, PTs were used as a coating in combination with alginate (AL) to improve the shelf life of Agaricus bisporus mushrooms under storage conditions. HPLC analysis identified phloroglucinol as the predominant component in the PT extract (18.1 %), which demonstrated an 86 ± 1.02 % radical scavenging activity in the DPPH test. The PPO enzyme activity significantly decreased from 320.34 ± 2.1 units to 34.4 ± 1.4 units in the presence of 1.5 mL of PT extract. The PT extract's antifungal properties were observed through well diffusion assays, mycelial growth inhibition, and scanning electron microscopy on treated spoilage mold colonies. Better preservation of the physicochemical properties of mushrooms coated with AL + PT was confirmed through various tests, including assessments of weight loss, browning, malondialdehyde levels, total phenol content, and vitamin C content. Additionally, sensorial tests and evaluations of visual and microstructure changes during storage at 4 °C confirmed the enhanced preservation after treatment. Findings indicated that in addition to the antifungal properties of S. ilicifolium-derived PT, which can act as a natural antifungal, this substance, when used in combination with AL coating, can increase the shelf life of A. bisporus mushrooms 12 d of storage at 4 °C.