Garden pruning waste from Cynodon sp. is a lignocellulosic resource with high lignin content, which limits anaerobic digestion efficiency. White-rot fungi degrade biomass through solid-state fermentation (SSF). The efficacy of these organisms, however, depends on the balanced removal of lignin and the subsequent preservation of fermentable carbohydrates. The present study evaluated the effect of SSF durations (8, 21, and 36 days) with Trametes hirsuta on enzymatic activity and subsequent biogas production. Laccase activity increased progressively, reaching 983.84 U/L at 36 days, while manganese and versatile peroxidases peaked at 21 days. Fungal-pretreated samples exhibited reduced methane yields, with a maximum of 225.32 NmL/gVS at 8 days, compared with untreated biomass (381.66 NmL/gVS). The total lignin content increased across treatments, suggesting the formation of pseudo-lignin during autoclave sterilization, while glucose and xylose decreased. These results underscore the complexity of optimizing fungal pretreatment and highlight the need to balance fermentation time to preserve carbohydrates while modifying lignin structure.

Grape pomace (GP), a major wine industry residue, contains substantial amounts of phenolic bioactive compounds whose valorization potential remains underexploited. In this study, pomaces from the Syrah, Malbec, Cabernet Sauvignon, Tempranillo, Nebbiolo-Sangiovese (blend), Cabernet Franc, Merlot, and Ensamble varieties were characterized in terms of total phenolic content (TPC), flavonoids, anthocyanins, tannins, and antioxidant capacity. Grape pomace flour (GPF) was obtained by drying, milling, and sieving (<250 µm) GP at 60 °C, and its functional properties were compared with GP and two commercial pomace flours (H1 and H2). The GPFs had a TPC of 3.48–12.06 mg gallic acid equivalents g⁻¹ dry basis (d.b.), flavonoid content of 11.78–71.65 mg quercetin equivalents g⁻¹ d.b., anthocyanin content of 41.46–291.85 mg cyanidin-3-glucoside equivalents g⁻¹ d.b., tannin content of 18.85–45.98 mg (+)-catechin equivalents g⁻¹ d.b., and antioxidant capacity of 304.2–768.3 μmol Trolox equivalents g⁻¹ d.b. The Malbec variety exhibited the best bioactive profile and was incorporated into a gelatin-based gummy matrix. Color and bioactive compound stability were measured over 30 days of storage at 40 °C and compared with a commercial flour (H1). The valorization of GP through drying and milling is a viable strategy for obtaining a flour with potential as a functional ingredient due to its bioactive composition and as a natural colorant in the food industry.

Garden pruning waste from Cynodon sp. is a lignocellulosic resource with high lignin content, which limits anaerobic digestion efficiency. While white-rot fungi can delignify biomass through solid-state fermentation (SSF), their efficacy depends on balancing lignin removal with preservation of fermentable carbohydrates. This study evaluated the effect of SSF times (8, 21, and 36 days) with Trametes hirsuta on enzymatic activity and subsequent biogas production. Laccase activity increased progressively, reaching 983.84 U/L at 36 days; whereas manganese and versatile peroxidases peaked at 21 days. Fungal-pretreated samples exhibited lower methane yields, a maximum of 225.32 NmL/gVS at 8 days, compared to untreated biomass (381.66 NmL/gVS). Total lignin content apparently increased across treatments, suggesting pseudo-lignin formation during autoclave sterilization, while glucose and xylose decreased. Biological pretreatment affected methane production by reducing sugar availability, potentially forming inhibitory furanic compounds and antimicrobial metabolites, thereby negating the benefits of enzymatic delignification. These results underscore the complexity of optimizing fungal pretreatment and highlight the need to balance fermentation time to preserve carbohydrates while modifying lignin structure.