# Antioxidant and Aromatic Properties of Aqueous Extracts of Pleurotus nebrodensis as Potential Food Ingredients

## TL;DR

This study compares two methods for extracting bioactive compounds from Pleurotus nebrodensis mushrooms, finding that each method affects antioxidant and aroma properties differently.

## Contribution

The study introduces a comparison of freeze–thaw and ultrasound-assisted extraction methods for preserving both antioxidant and aromatic qualities in Pleurotus nebrodensis.

## Key findings

- Ultrasound-assisted extraction yields higher phenolics and flavonoids but lower procyanidins and ascorbic acid compared to freeze–thaw extraction.
- Freeze–thaw extraction better preserves volatile alcohols and aldehydes like 1-octen-3-ol and hexanal.
- Gallic acid is the most abundant phenolic compound in all P. nebrodensis extracts.

## Abstract

Pleurotus nebrodensis has raised the interest of the food and nutraceutical industry due to its valuable organoleptic characteristics coupled with antibacterial and antitumor properties. Given this interest, this study aimed to identify effective, cheap, and eco-friendly technologies to prepare extracts able to convey the bioactive compounds while retaining the typical mushroom aroma. Two aqueous extracts were prepared based on a freeze–thaw (FT) and ultrasound-assisted (UA) method. The extracts, both in liquid and lyophilized form, were analyzed by HPLC to determine the phenolic compounds. Moreover, the volatile organic compounds, total phenolics, total flavonoids, total phenolic acids, procyanidins, and ascorbic acid were determined, while the antioxidant activity was assessed by DPPH (2,2-diphenyl-1-picrylhydrazyl) and ABTS radical scavenging activity, ferric-reducing/antioxidant power (FRAP), and cupric-reducing antioxidant capacity (CUPRAC) assays. The UA extraction showed significantly higher (p < 0.05) phenolics (5.05 vs. 4.02 µg/g DW) and flavonoids (0.74 vs. 0.23 µg/g DW) but lower procyanidins (12.33 vs. 15.93 µg/g DW) and ascorbic acid (6.23 vs. 7.02 µg/g DW) than the FT extracts, resulting in lower antioxidant activity. Among the phenolic constituents, gallic acid was found to be the most abundant in all P. nebrodensis extracts. Regarding aroma, FT more effectively preserved volatile alcohols and aldehydes—particularly 1-octen-3-ol and hexanal—while UA led to greater volatile losses. These results highlight that the extraction method significantly affects both antioxidant composition and volatile integrity, with implications for designing P. nebrodensis-based food ingredients.