Growth-promoting activity of polyphenolic extracts from carrot pomace and fermented carrot pomace on Aspergillus brasiliensis

This study investigated the effect of polyphenolic extracts derived from carrot pomace (CP) and fermented carrot pomace (FCP) on the growth of Aspergillus brasiliensis, a filamentous fungus recognized for its enzymatic activity and potential in feed fermentation. Polyphenols were recovered by microwave-assisted extraction and their total content quantified using the Folin–Ciocâlteu assay. Standardized extracts were evaluated in vitro against A. brasiliensis cultures. Both preparations markedly enhanced fungal proliferation following a dose–response pattern. The strongest stimulation appeared within the intermediate to high dose range (37.8–151 µg/mL TP), where growth surpassed control values by more than 250%. At lower doses (4.72–9.45 µg/mL TP), CP preserved its growth-promoting capacity, whereas FCP progressively lost activity, indicating that the fermentation process modifies the polyphenolic profile in a manner that diminishes stimulation at reduced concentrations. The findings reveal a twofold function of carrot-derived polyphenols, promoting fungal biomass accumulation while also conferring antimicrobial activity against selected bacterial strains. Taken together, the data support the incorporation of CP and FCP into feed substrates intended for A. brasiliensis solid-state fermentation, thereby improving fermentation yield and nutritional attributes. The present work contributes new evidence on the interplay between polyphenols and beneficial fungi and identifies practical avenues for valorizing agroindustrial residues in sustainable livestock nutrition.