Volatile profiling of rice and cocoa by-product substrates for edible mushroom cultivation: a circular approach to flavour potential

The BIO.FUNGI.PRO project (PRIN 2022YXLFYH) focuses on designing an integrated, bio-based approach for the sustainable production of fungal proteins and fiber-rich ingredients by valorizing agri-food by-products, namely cocoa bean shells (CBS) and rice husks (RH). (1) By applying circular economy principles alongside advanced green technologies, the project aims to enhance mushroom cultivation processes and convert fungal biomass into functional ingredients for innovative, high-protein food products, ultimately leading to the creation of a sustainable “mushburger.” This study focuses on the characterization of volatile organic compounds (VOCs) emitted from raw matrices, including standard mushroom culture media, CBS- and RH-enriched substrates, and two commercial mushroom species, Agaricus bisporus and Pleurotus ostreatus. (2) Attention is given to CBS- and RH-enriched substrates and their influence on the aromatic profile of the final mushroom product and their contribution to the sensory quality of mushroom-based foods. Volatiles profiling was performed using Headspace Solid-Phase Microextraction coupled with Gas Chromatography–Mass Spectrometry (HS-SPME-GC-MS) employing an Agilent 8890 GC System coupled to an Agilent 5977C MSD and an HP-5ms Ultra Inert capillary column (30 m x 0.25 mm × 0.25 um). The DVB/CAR/PDMS (50/30 um dj - 2 cm length) was employed for the extraction and pre-concentration of volatiles from the sample headspace (HS). The base culture medium was analyzed in its original form and after enrichment with CBS (50/50), RH (50/50) and both (50/25/25). Meanwhile, the analysis of oven-dried fungal samples enabled the identification of more than 50 compounds in A. bisporus and over 40 in P. ostreatus. These preliminary results establish an analytical framework for monitoring changes in volatile compounds throughout the fungal production chain under different enriched media. They also represent a first step toward supporting the development of safe, stable, and sensorially acceptable mushroom-based protein foods within a circular bioeconomy model. Aknowledgement This study is part of the BIO.FUNGI.PRO research project funded by the Italian Ministero dell’Università e della Ricerca (MUR) PRIN PNRR project no. 2022YXLFYH. The authors thank all the project’s partners. Bibliography 1. O. Rojo-Poveda, L. Barbosa-Pereira, G. Zeppa, C. Stévigny. Cocoa Bean Shell—A By-Product with Nutritional Properties and Biofunctional Potential. Nutrients, 2020 2. JS. Dickschat. Fungal volatiles – a survey from edible mushrooms to moulds. Natural Product Report, 2017