BIOTECHNOLOGICAL VALORIZATION OF GRAPE WASTES BY SOLID STATE FERMENTATION

Grapes (Vitis spp.) are sources of biogenic amines, which are also found in derived products such as juices and wines. Brazil is a major producer of grape juice, an activity that generates agro-industrial waste with potential for biotechnological valorization. These wastes may contain biogenic amines and amino acids of interest, whose concentrations can be altered through fermentation. This study aimed to investigate the concentrations of amino acids and biogenic amines in wastes from four grape cultivars (Bordô, Magna, Niagara Rosada, and Violeta) before and after solid-state fermentation (SSF) using filamentous fungi of the genus Aspergillus spp., to evaluate the potential of this process to increase the concentrations of these compounds and characterize their profiles. Wastes were collected immediately after juice production and stored at −20 °C. Unfermented samples were homogenized and lyophilized at −60 °C for 48 h. For SSF, the wastes were homogenized, weighed into bioreactors, inoculated with spores of Aspergillus niger and Aspergillus oryzae, and incubated at 30°C for 168 h, followed by lyophilization at −60°C for 48 h. The extracts were analyzed by ultra-high-performance liquid chromatography (UHPLC). The data were subjected to Bartlett’s and Shapiro–Wilk tests, followed by analysis of variance (ANOVA) and Tukey’s test. A total of 15 compounds were identified, comprising amino acids and their derivatives, monoamines, diamines, and polyamines. The results showed that SSF altered biogenic amine concentrations, increasing several compounds, including L-DOPA, serotonin, dopamine, spermine, and putrescine. Notably, agmatine, which was not detected in the unfermented samples, was detected after fermentation. This finding may be associated with an alternative metabolic pathway in Aspergillus spp. involving an enzyme responsible for arginine decarboxylation. Conversely, the decrease in compounds such as L-tryptophan may be attributed to their utilization in the synthesis of proteins, enzymes, and other metabolites involved in fungal metabolism. Furthermore, quality indices (CQI, BAI, and AI) were calculated to assess the biogenic amine profiles of the samples. Although CQI and BAI were originally developed to evaluate food products of animal origin, they have also been applied to plant-based products, including juices and wines. The AI relates the concentrations of amines potentially harmful to health or indicative of spoilage (histamine, tyramine, putrescine, and cadaverine) to those associated with beneficial physiological functions (dopamine, serotonin, melatonin, spermidine, and spermine). This index was proposed for plant-based foods, with a safety threshold of 50 mg/L. Both unfermented and fermented grape wastes remained within this limit. In conclusion, SSF has the potential to modify the amino acid and biogenic amine profiles of grape wastes, thereby supporting their biotechnological valorization. However, further studies are needed to elucidate the underlying metabolic mechanisms and assess the safety of potential applications.

Acknowledgments: CNPq project (151752/2024-9) and project (307571/2019-0).